Forem: Trần Xuân Ái

HTML to JSX: Common Conversion Problems Frontend Developers Still Make

Trần Xuân Ái — Wed, 27 May 2026 07:57:44 +0000

If you've worked with React,
you've probably copied HTML into JSX at least once.

And then immediately got errors like:

Unexpected token
Invalid DOM property
Adjacent JSX elements must be wrapped
Objects are not valid as a React child

Converting HTML to JSX sounds simple,
but there are many small differences that constantly trip developers up.

In this article, we'll cover:

HTML vs JSX differences
common HTML to JSX mistakes
React attribute conversion
inline style issues
SVG conversion problems
how to convert HTML to JSX faster

Why JSX Exists

JSX stands for JavaScript XML.

It allows developers to write UI markup directly inside JavaScript.

Example:

function App() {
  return <h1>Hello World</h1>;
}

React transforms JSX into:

JavaScript function calls
virtual DOM elements

This makes component-driven UI development much easier.

HTML Is NOT JSX

Many beginners assume JSX is just HTML inside JavaScript.

But JSX has important differences.

For example,
this valid HTML:

<label class="title">Hello</label>

will fail in React JSX.

Correct JSX:

<label className="title">Hello</label>

Common HTML to JSX Conversion Problems

class → className

This is the most common mistake.

HTML:

<div class="card"></div>

JSX:

<div className="card"></div>

React uses className
because class is a reserved JavaScript keyword.

for → htmlFor

HTML:

<label for="email"></label>

JSX:

<label htmlFor="email"></label>

Inline Styles Become Objects

HTML:

<div style="color:red;"></div>

JSX:

<div style={{ color: "red" }}></div>

This is one of the biggest HTML to JSX conversion issues.

Self-Closing Tags

HTML allows:

<img src="image.jpg">

But JSX requires:

<img src="image.jpg" />

Same for:

input
br
hr
meta

Multiple Root Elements

This breaks JSX:

<h1>Hello</h1>
<p>World</p>

Correct version:

<>
  <h1>Hello</h1>
  <p>World</p>
</>

Or:

<div>
  <h1>Hello</h1>
  <p>World</p>
</div>

Why HTML to JSX Conversion Matters

Frontend developers constantly:

copy UI snippets
convert templates
migrate websites
reuse landing pages
adapt design exports

This makes HTML to JSX conversion a daily workflow.

Especially for:

React
Next.js
Gatsby
Remix

developers.

SVG Conversion Problems in JSX

SVG is another common issue.

SVG attributes often break in React.

Example:

<svg stroke-width="2"></svg>

React JSX requires:

<svg strokeWidth="2"></svg>

Many SVG attributes become camelCase.

Examples:

stroke-width → strokeWidth
fill-rule → fillRule
clip-path → clipPath
Why Developers Use HTML to JSX Converters

Manually converting HTML to JSX is annoying.

Especially for:

large templates
Tailwind components
dashboard layouts
landing pages
SVG markup

Developers often need to:

fix attributes
convert inline styles
repair invalid JSX
clean formatting
React + Tailwind HTML Conversion

Tailwind UI snippets are often copied directly into React apps.

Example HTML:

<div class="bg-blue-500 text-white p-4">
  Button
</div>

JSX version:

<div className="bg-blue-500 text-white p-4">
  Button
</div>

Even simple conversions become repetitive quickly.

Why I Built an HTML to JSX Converter

I got tired of manually fixing:

className
inline styles
invalid attributes
SVG props

every time I copied HTML into React.

So I built a browser-based HTML to JSX converter focused on frontend developers.

Features:

instant HTML to JSX conversion
React-friendly formatting
SVG conversion support
clean indentation
copy-paste workflow
local browser processing

Try it here:

https://fullconvert.cloud/html-to-jsx

HTML to JSX Tips for React Developers
Use Fragments

Avoid unnecessary wrapper divs.

Prefer Functional Components

Modern React uses functional components by default.

Keep JSX Clean

Readable JSX is easier to maintain.

Validate SVG Attributes

SVG conversion issues are extremely common.

HTML to JSX for AI Coding Workflows

AI coding tools generate a lot of HTML snippets.

Developers frequently need to:

convert AI-generated HTML
adapt snippets to React
clean JSX output
fix invalid attributes

This made HTML to JSX tools even more useful recently.

Final Thoughts

HTML to JSX conversion is one of the most common frontend development workflows.

Understanding:

JSX syntax
React attributes
inline styles
SVG conversion

can save hours of debugging.

Whether you're building:

React apps
Next.js projects
dashboards
SaaS products
landing pages

a fast HTML to JSX converter becomes an essential frontend utility.

If you want a quicker way to convert HTML into React JSX,
you can try my browser-based HTML to JSX converter here:

https://fullconvert.cloud/html-to-jsx

CSS Box Shadows That Actually Look Professional

Trần Xuân Ái — Wed, 27 May 2026 07:14:34 +0000

Most CSS box shadows look terrible.

They're either:

too dark
too blurry
too sharp
too obvious
outdated
or copied from old Bootstrap examples

But modern UI design relies heavily on subtle shadows.

Good box shadows create:

depth
hierarchy
focus
visual separation
premium-looking interfaces

If you look at modern products like:

Linear
Vercel
Stripe
Notion
Framer
Apple
modern SaaS dashboards

you'll notice that shadows are used very differently compared to older websites.

In this article, we'll cover:

modern CSS box shadow techniques
why most shadows look bad
layered shadows
neumorphism
glow shadows
shadow performance tips
how developers generate better shadows quickly

Why Box Shadows Matter

Without shadows,
modern UI often feels:

flat
lifeless
difficult to scan

Shadows help users understand:

elevation
clickable areas
layering
modal depth
hover interactions

Even subtle shadows dramatically improve UI quality.

The Problem With Old Box Shadows

Many developers still use shadows like this:

box-shadow: 0 0 10px #000;

This usually looks:

harsh
outdated
unrealistic

Real-world shadows are softer and layered.

Modern UI uses:

lower opacity
larger blur radius
multiple shadow layers
softer spread
Understanding CSS Box Shadow

Basic syntax:

box-shadow:
  offset-x
  offset-y
  blur-radius
  spread-radius
  color;

Example:

box-shadow:
  0 10px 30px rgba(0,0,0,0.1);
Modern Shadow Example

Modern SaaS-style shadow:

box-shadow:
  0 1px 2px rgba(0,0,0,0.05),
  0 8px 24px rgba(0,0,0,0.08);

This creates:

softer depth
more realistic elevation
premium UI feel

Layered shadows look much better than single-layer shadows.

Why Multiple Shadows Look Better

Real-world lighting creates multiple shadow layers.

Using multiple CSS shadows creates:

smoother falloff
realistic depth
softer transitions

Example:

box-shadow:
  0 2px 4px rgba(0,0,0,0.04),
  0 12px 24px rgba(0,0,0,0.08);

This is common in:

dashboards
modals
cards
floating UI
modern landing pages
Common Box Shadow Mistakes
Shadows Too Dark

Overly dark shadows make UI feel old.

Bad:

box-shadow:
  0 10px 30px rgba(0,0,0,0.5);

Better:

box-shadow:
  0 10px 30px rgba(0,0,0,0.08);
Blur Radius Too Small

Small blur radius creates harsh edges.

Modern UI prefers:

softer blur
subtle transitions
Too Much Spread

Large spread values often feel unnatural.

Black Shadows Everywhere

Modern shadows often use:

blue tint
purple tint
subtle ambient color

instead of pure black.

Soft UI and Neumorphism

Neumorphism became a major UI trend.

It combines:

inner shadows
soft highlights
low contrast depth

Example:

box-shadow:
  8px 8px 16px #d1d9e6,
  -8px -8px 16px #ffffff;

Used carefully,
this creates elegant soft UI effects.

Glow Shadows

Modern startup websites often use glow effects.

Example:

box-shadow:
  0 0 40px rgba(99,102,241,0.4);

Popular for:

buttons
hero sections
AI products
Web3 websites
futuristic UI
Box Shadows in Dark Mode

Dark mode requires different shadows.

Traditional shadows disappear on dark backgrounds.

Developers often use:

subtle borders
ambient glow
lighter opacity
layered contrast

instead of pure black shadows.

CSS Box Shadow Performance Tips

Heavy shadows can hurt rendering performance.

Avoid:

giant blur radius
excessive shadow layers
animated huge shadows

Especially on:

mobile devices
low-end laptops
Tailwind CSS Shadows

Tailwind CSS made modern shadows much easier.

Example:

<div class="shadow-xl">
</div>

Popular Tailwind shadow utilities:

shadow-sm
shadow-md
shadow-lg
shadow-xl
shadow-2xl
Why Developers Use Box Shadow Generators

Writing shadows manually is annoying.

Most developers struggle with:

blur balance
opacity
realism
neumorphism values
glow effects

So many developers use box shadow generators to:

preview shadows visually
tweak blur radius
export CSS instantly
test neumorphism
generate layered shadows
Why I Built a Box Shadow Generator

I kept needing modern shadows for:

landing pages
SaaS dashboards
cards
buttons
modal windows

Most existing generators:

looked outdated
generated ugly shadows
lacked neumorphism
had poor UX

So I built a cleaner developer-focused Box Shadow Generator.

Features:

live shadow preview
layered shadows
neumorphism
glow shadows
CSS export
Tailwind-friendly values
copy-paste workflow

Try it here:

https://fullconvert.cloud/box-shadow-generator

Modern Shadow Trends in 2026

Current trends include:

ultra-soft shadows
glassmorphism
glow effects
ambient lighting
layered elevation
dark mode shadows

Most modern UI systems rely heavily on subtle shadow design.

Final Thoughts

Good CSS box shadows can completely transform UI quality.

Modern shadows should feel:

soft
subtle
layered
realistic

Whether you're building:

SaaS apps
startup landing pages
dashboards
portfolios
admin panels

well-designed shadows dramatically improve the user experience.

If you want a faster way to generate production-ready shadows,
you can try my browser-based Box Shadow Generator here:

https://fullconvert.cloud/box-shadow-generator

CSS Gradient Trends in 2026 (And How Developers Actually Use Them)

Trần Xuân Ái — Wed, 27 May 2026 07:12:46 +0000

CSS gradients are everywhere now.

Modern websites no longer rely on:

flat colors
generic backgrounds
heavy image assets

Instead, developers are increasingly using:

linear gradients
radial gradients
mesh gradients
animated gradients
layered gradients

to create modern UI and visually appealing landing pages.

If you've browsed recent SaaS websites,
you've probably seen gradients used in:

hero sections
buttons
cards
dashboards
pricing sections
app backgrounds

In this article, we'll look at:

modern CSS gradient trends
why gradients became popular again
linear vs radial vs mesh gradients
gradient performance tips
how developers generate gradients quickly

Why CSS Gradients Became Popular Again

A few years ago,
many websites used:

flat Material Design colors
stock illustrations
giant PNG backgrounds

But frontend design evolved.

Modern interfaces now focus on:

depth
glow
visual hierarchy
subtle motion
immersive UI

Gradients help create this effect naturally.

Today, gradients are heavily used by:

Stripe
Vercel
Linear
Framer
Notion
AI startups
SaaS landing pages

What Is a CSS Gradient?

A CSS gradient is a generated image created directly with CSS.

Instead of loading an external image,
the browser renders the gradient dynamically.

Example:

background: linear-gradient(
  135deg,
  #6366f1,
  #8b5cf6
);

Benefits:

lightweight
scalable
responsive
easy to customize
no image download required
Linear Gradients

Linear gradients are the most common type.

Example:

background: linear-gradient(
  to right,
  #06b6d4,
  #3b82f6
);

Used for:

hero backgrounds
CTA buttons
cards
overlays
banners

Linear gradients work especially well in:

Tailwind CSS
React apps
SaaS UI
Radial Gradients

Radial gradients spread outward from a center point.

Example:

background: radial-gradient(
  circle,
  #9333ea,
  #0f172a
);

Popular for:

glow effects
spotlight effects
futuristic UI
dashboard visuals
Mesh Gradients

Mesh gradients became one of the biggest frontend design trends recently.

They're heavily used in:

AI websites
startup landing pages
Web3 projects
modern app interfaces

Mesh gradients combine:

multiple color layers
blur effects
soft transitions

This creates more organic visuals.

Why Developers Prefer CSS Gradients Over Images

Traditional image backgrounds cause problems:

large file sizes
poor responsiveness
difficult editing
retina scaling issues

CSS gradients solve all of these.

Advantages:

instant rendering
smaller page size
responsive design
dynamic customization
dark mode compatibility
CSS Gradient Performance Benefits

CSS gradients are often more performant than image assets.

Benefits:

faster loading
lower bandwidth usage
better Lighthouse scores
improved Core Web Vitals
better mobile performance

This indirectly improves:

SEO
UX
conversion rates
Modern Gradient Design Trends in 2026

Current frontend gradient trends include:

neon gradients
aurora gradients
glassmorphism
dark mode gradients
pastel gradients
cyberpunk colors
animated gradients
blurred glow effects

Developers increasingly combine gradients with:

SVG backgrounds
blur filters
noise textures
layered transparency
Common Gradient Mistakes
Over-Saturated Colors

Too many bright colors make UI look messy.

Poor Contrast

Bad gradients reduce readability.

Always test:

text contrast
accessibility
dark mode visibility
Excessive Gradient Layers

Too many blur layers hurt performance.

Keep gradients lightweight.

Tailwind CSS Gradient Example

Tailwind makes gradients extremely easy.

Example:

<div class="bg-gradient-to-r from-cyan-500 to-blue-500">
</div>

This is one reason gradients exploded in popularity.

Gradient Ideas Developers Use Most

Popular gradient combinations:

purple → blue
pink → orange
cyan → indigo
dark navy → violet
emerald → cyan

These are common in:

startup websites
developer tools
dashboards
portfolio websites
Why I Built a Gradient Generator

I constantly needed gradients for:

landing pages
UI mockups
hero sections
dashboard interfaces

But most gradient tools:

had outdated UI
exported messy CSS
lacked modern presets
focused too much on designers

So I built a developer-focused Gradient Generator.

Features:

CSS gradients
SVG gradients
Tailwind export
React export
live preview
copy-paste code
modern gradient presets

Try it here:

https://fullconvert.cloud/gradient-generator

CSS Gradient Tips for Frontend Developers
Use Gradients Sparingly

Gradients work best as accents.

Combine With Blur

Subtle blur creates premium-looking UI.

Test Mobile Devices

Some gradients look different on OLED screens.

Use Accessible Contrast

Always ensure text remains readable.

Final Thoughts

CSS gradients are no longer just a design trend.

They've become a core part of modern frontend development.

They're:

lightweight
responsive
scalable
SEO-friendly
visually powerful

Whether you're building:

SaaS products
startup landing pages
dashboards
portfolios
AI apps

modern CSS gradients can dramatically improve visual quality.

If you want a quick way to generate production-ready gradients,
you can try my browser-based Gradient Generator here:

https://fullconvert.cloud/gradient-generator

I Built a Free SVG Background Generator for Developers

Trần Xuân Ái — Wed, 27 May 2026 07:02:06 +0000

Modern websites need good visuals.

But most developers don't want to:

open Figma
search Dribbble for hours
export giant PNG files
manually tweak backgrounds

At the same time, plain white sections feel outdated.

That's why SVG backgrounds have become extremely popular in:

landing pages
SaaS websites
portfolios
dashboards
hero sections
startup websites

So I built a free SVG Background Generator focused specifically on developers and frontend workflows.

In this article, we'll look at:

why SVG backgrounds are everywhere
why SVG is better than PNG
how modern SVG backgrounds work
common frontend SVG techniques
how to generate SVG backgrounds quickly

Why SVG Backgrounds Became So Popular

A few years ago,
most websites used:

JPG hero images
PNG textures
large background illustrations

But modern frontend development shifted toward:

lightweight assets
scalable graphics
responsive UI
animated interfaces
minimal design systems

SVG backgrounds solve many of these problems.

SVG files are:

scalable
tiny in size
responsive
editable
CSS-friendly
animation-friendly

This makes SVG ideal for modern web design.

Common SVG Background Styles

Today you'll see SVG backgrounds everywhere.

Popular styles include:

waves
blobs
gradients
grids
dots
mesh patterns
abstract lines
layered curves
peaks
geometric shapes

Examples:

Stripe
Linear
Vercel
Clerk
Framer
modern SaaS landing pages

Why SVG Is Better Than PNG

Many developers still export huge PNG backgrounds from design tools.

This creates problems:

large file sizes
blurry scaling
poor responsiveness
slow loading

SVG solves this.

PNG Problems

PNG backgrounds:

scale poorly
increase bandwidth
look blurry on retina screens
are harder to edit

SVG Advantages

SVG backgrounds:

scale infinitely
remain sharp
are lightweight
work great with CSS
can be animated easily

Example SVG:

<svg viewBox="0 0 1440 320">
  <path fill="#0099ff"
    d="M0,192L48,181.3C96,171,192,149,288,154.7C384,160,480,192,576,192C672,192,768,160,864,138.7C960,117,1056,107,1152,122.7C1248,139,1344,181,1392,202.7L1440,224L1440,320L0,320Z">
  </path>
</svg>

SVG Backgrounds Work Great With Frontend Frameworks

SVG backgrounds are especially useful in:

React
Next.js
Vue
Tailwind CSS
Astro
Nuxt Because SVG integrates directly into HTML and CSS.

Example:

background-image: url('/wave.svg');
background-size: cover;

Or inline SVG:

<div class="hero-bg">
  <svg>...</svg>
</div>

The Problem With Most SVG Generators

I tried many SVG background generators online.

Most had issues:

outdated UI
limited customization
exported messy SVG code
poor mobile support
giant SVG output
too many ads

Some tools were also too designer-focused.

I wanted something faster for developers.

Building an SVG Background Generator for Developers

I built a browser-based SVG Background Generator focused on:

frontend workflows
fast exports
clean SVG output
responsive design
copy-paste usage

Features include:

SVG waves
SVG blobs
SVG grids
SVG gradients
abstract backgrounds
layered SVG shapes
customizable colors
live preview

Try it here:

https://fullconvert.cloud/svg-background-generator

Why Developers Love SVG Backgrounds

SVG backgrounds help developers:

improve landing page quality
build modern UI faster
reduce design dependency
avoid heavy image assets
create unique branding

Especially for:

SaaS products
startup websites
portfolios
developer tools
AI products

- dashboards

SVG Background Performance Benefits

Performance matters.

SVG backgrounds are often much smaller than PNG alternatives.

Benefits:

faster page speed
lower bandwidth
improved Lighthouse scores
better Core Web Vitals
better mobile performance

This helps both:

- user experience

SVG Background SEO Benefits

Many developers ignore how visuals affect SEO.

But:

faster load speed
smaller assets
responsive graphics

all improve:

Google PageSpeed
Lighthouse performance
mobile usability

SVG backgrounds can indirectly help SEO performance.

Modern SVG Design Trends

Current SVG trends include:

mesh gradients
layered waves
abstract blobs
noise textures
soft gradients
glassmorphism
neumorphism backgrounds

Modern websites increasingly rely on SVG-based UI systems.

SVG Background Tips
Keep SVG Files Small

Avoid:

excessive nodes
giant paths
unnecessary filters
Use Responsive ViewBox

Always define:

viewBox="0 0 1440 320"

This keeps SVG scalable.

Prefer Inline SVG for Animation

Inline SVG allows:

CSS animation
JS manipulation
React component usage
Final Thoughts

SVG backgrounds have become a core part of modern frontend design.

They're:

scalable
lightweight
responsive
SEO-friendly
developer-friendly

Whether you're building:

landing pages
SaaS dashboards
portfolios
startup websites

SVG backgrounds can dramatically improve visual quality without hurting performance.

If you're looking for a quick way to generate modern SVG backgrounds,
you can try my browser-based SVG Background Generator here:

https://fullconvert.cloud/svg-background-generator

10 JSON Formatting Tricks Every Developer Should Know

Trần Xuân Ái — Wed, 27 May 2026 06:55:51 +0000

If you work with APIs, frontend applications, or backend services, you deal with JSON every single day.

But most developers only scratch the surface of what proper JSON formatting can do.

Good JSON formatting helps you:

debug APIs faster
reduce syntax errors
inspect large payloads
validate API responses
improve developer productivity
troubleshoot frontend/backend issues

In this article, we'll cover:

JSON formatting basics
common JSON mistakes
JSON debugging tricks
JSON validation tips
how to format JSON faster
tools for JSON formatting and validation

What Is JSON?

JSON stands for JavaScript Object Notation.

It is the most widely used data format for:

REST APIs
frontend applications
configuration files
cloud services
server communication

Example JSON:

{
  "name": "John",
  "email": "john@example.com",
  "role": "admin"
}

JSON is lightweight, readable, and supported almost everywhere.

Why JSON Formatting Matters

Poorly formatted JSON causes:

debugging headaches
API parsing errors
frontend crashes
failed requests
invalid payloads

A proper JSON formatter helps developers:

visualize nested structures
validate syntax
minify payloads
prettify responses
inspect API data quickly

1. Always Pretty Print Large JSON

Large JSON payloads become unreadable quickly.

Bad:

{"users":[{"id":1,"name":"John"},{"id":2,"name":"Jane"}]}

Better:

{
  "users": [
    {
      "id": 1,
      "name": "John"
    },
    {
      "id": 2,
      "name": "Jane"
    }
  ]
}

Pretty printing JSON dramatically improves debugging speed.

2. Validate JSON Before Sending API Requests

One missing comma can break an entire API request.

Common invalid JSON mistakes:

trailing commas
single quotes
missing brackets
malformed arrays
invalid escape characters

Broken JSON example:

{
  "name": "John",
  "email": "john@example.com",
}

The trailing comma makes this invalid.

3. Use JSON Formatting for API Debugging

When debugging APIs, formatted JSON makes patterns easier to spot.

Useful for:

GraphQL responses
REST APIs
authentication payloads
webhook events
Firebase responses

Example workflow:

API request → JSON response → format JSON → inspect fields → debug issue

4. Minify JSON for Production

Pretty JSON is great for development,
but minified JSON reduces payload size.

Pretty JSON:

{
  "name": "John",
  "role": "admin"
}

Minified JSON:

{"name":"John","role":"admin"}

This helps:

reduce bandwidth
improve API performance
decrease transfer size

5. Learn Common JSON Errors

Unexpected Token

Usually caused by:

invalid quotes
malformed syntax
broken arrays

Unexpected End of JSON Input

Typically means:

incomplete JSON response
truncated payload
server-side bug

Invalid JSON Parse Error

Common causes:

comments inside JSON
trailing commas
undefined values

6. JSON Is NOT JavaScript Objects

Many beginners confuse JSON with JavaScript objects.

JavaScript object:

{
  name: "John"
}

Valid JSON:

{
  "name": "John"
}

JSON requires:

double quotes
valid syntax
serializable values

7. Use JSON Formatting for Authentication Debugging

Authentication systems often return JSON payloads.

Example:

{
  "token": "jwt_here",
  "expiresIn": 3600,
  "user": {
    "id": 1,
    "role": "admin"
  }
}

Formatting helps inspect:

JWT responses
OAuth payloads
auth sessions
API scopes

8. Large Nested JSON Requires Structure

Deeply nested JSON becomes difficult to debug.

Good JSON formatting helps visualize:

arrays
objects
nested relationships
API schemas

Especially important for:

MongoDB
Firebase
GraphQL
Elasticsearch
REST APIs

9. JSON Validation Saves Hours

A JSON validator can instantly detect:

invalid syntax
missing commas
malformed arrays
incorrect nesting

This is much faster than manually debugging large payloads.

10. Use a Fast Browser-Based JSON Formatter

Most online JSON formatter tools:

feel slow
contain ads
upload data to servers
break formatting
struggle with large payloads

I wanted a faster developer-friendly JSON formatter,
so I built one that works directly in the browser.

Features:

JSON formatting
JSON validation
JSON minify
syntax highlighting
instant parsing
local processing

Try it here:

https://fullconvert.cloud/json-formatter-validator

Bonus: JSON Formatting Tips for Frontend Developers

If you're working with:

React
Next.js
Vue
Angular
Node.js

you'll constantly inspect JSON responses.

A fast JSON formatter becomes one of the most useful daily developer tools.

Final Thoughts

JSON powers modern web development.

Understanding how to:

format JSON
validate JSON
debug JSON
minify JSON

can dramatically improve your development workflow.

Whether you're building:

APIs
frontend apps
dashboards
SaaS products
mobile apps

proper JSON formatting is an essential developer skill.

How to Decode JWT Tokens Without Sending Data to a Server

Trần Xuân Ái — Wed, 27 May 2026 06:51:46 +0000

If you work with APIs, authentication, or frontend applications, you've probably seen a JWT token before.

JWTs are everywhere:

OAuth
Firebase
Supabase
NextAuth
Auth0
Clerk
custom backend authentication systems

But many developers still paste JWT tokens into random online JWT decoder websites without realizing the security implications.

In this article, we'll look at:

what a JWT token actually is
how JWT decoding works
common JWT debugging issues
how to decode JWT tokens locally in your browser
how to inspect JWT payloads safely

What Is a JWT Token?

JWT stands for JSON Web Token.

A JWT token is a compact string format commonly used for:

authentication
authorization
API sessions
identity verification

A typical JWT looks like this:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
.
eyJ1c2VySWQiOjEyMywiZW1haWwiOiJ0ZXN0QGV4YW1wbGUuY29tIn0
.
abc123signature

A JWT consists of 3 parts:

Header
Payload
Signature

JWT Header

The JWT header contains metadata about the token.

Example:

{ "alg": "HS256", "typ": "JWT" }

Common JWT algorithms:

HS256
RS256
ES256

JWT Payload

The JWT payload contains claims.

Example:

{ "userId": 123, "email": "test@example.com", "role": "admin" }

Common JWT claims:

This is usually the part developers want to inspect when debugging authentication issues.

JWT Signature

The JWT signature is used to verify integrity.

It prevents attackers from modifying the token payload.

Important:
Decoding a JWT does NOT mean verifying it.

Many developers confuse:

JWT decode
JWT verify

These are different operations.

Why Developers Need a JWT Decoder

A JWT decoder is useful for:

debugging expired tokens
inspecting payload claims
checking user roles
validating OAuth flows
troubleshooting authentication bugs
inspecting API sessions

Typical frontend debugging workflow:

Login → receive token → decode JWT → inspect payload → debug auth issue

The Problem With Most JWT Decoder Websites

Many online JWT decoder tools:

upload your token to servers
inject ads
track requests
feel slow
expose sensitive data

This is risky because JWT payloads sometimes contain:

emails
user IDs
internal metadata
API scopes
authentication claims

Even though JWT payloads are Base64 encoded (not encrypted),
you still should avoid sending production tokens to random services.

How JWT Decoding Works

JWT decoding is actually simple.

The payload is Base64URL encoded JSON.

You can decode it locally without contacting any server.

The process:

JWT → split by "." → decode payload → parse JSON

Example:

const payload = token.split(".")[1]; const decoded = JSON.parse(atob(payload)); console.log(decoded);

Common JWT Errors

1. Invalid Signature

Usually caused by:

wrong secret
modified token
incorrect algorithm

2. JWT Expired

Check the exp claim:

{ "exp": 1750000000 }

3. Malformed JWT

A valid JWT must contain 3 sections:

header.payload.signature

4. Wrong Algorithm

Example:

backend uses RS256
frontend expects HS256

This breaks verification.

Decode JWT Tokens Locally in Your Browser

I got tired of using slow JWT decoder websites filled with ads,
so I built a simple browser-based JWT Decoder tool.

Features:

local JWT decoding
no server upload
instant parsing
formatted JSON output
JWT header inspection
payload inspection
signature validation support

Try it here:

https://fullconvert.cloud/jwt-decoder

You can also generate tokens here:

https://fullconvert.cloud/jwt-encoder

JWT Security Tips

Never store sensitive secrets inside JWT payloads.

JWT payloads are only encoded, not encrypted.

Avoid putting:

passwords
API secrets
private credentials

inside JWT claims.

Final Thoughts

JWT authentication is now part of almost every modern web application.

Understanding how JWT decoding works can save hours of debugging time.

Whether you're working with:

React
Next.js
Node.js
Express
Firebase
Supabase
Auth0

a good JWT decoder becomes essential in your daily developer workflow.

If you frequently debug authentication issues,
using a local browser-based JWT decoder is usually the safest and fastest option.

Why HEIC to JPG Is Still a Massive Problem for iPhone Users?

Trần Xuân Ái — Wed, 27 May 2026 06:38:48 +0000

Why HEIC to JPG Is Still a Massive Problem for iPhone Users

If you’ve ever taken photos on an iPhone and tried to upload them somewhere, you’ve probably seen this happen:

“Unsupported file format”
Upload failed
Preview not available
Image won’t open on Windows
Website only accepts JPG or PNG

The problem is usually one thing:

HEIC.

Apple introduced HEIC to reduce image size while keeping high quality, but compatibility is still messy across many websites, tools, and older systems.

Where People Usually Hit This Problem

Government forms
Job application portals
CMS uploads
WordPress media libraries
Older Windows PCs
Online PDF tools
Banking & document systems

A lot of platforms still expect JPG.

So users end up:

emailing images to themselves
taking screenshots
using random desktop apps
searching “how to convert HEIC to JPG”

The Bigger Problem

Most people don’t actually want “image conversion software”.

They just want:

a fast upload
privacy
no installation
no watermark
something that works instantly

That’s one reason browser-based tools are growing quickly.

What I’m Building

I’ve been working on:
https://fullconvert.cloud

The goal is simple:

Make annoying file conversion tasks feel effortless.

Current workflows include:

HEIC to JPG
WebP to PNG
JPG to PDF
Image compression
PDF utilities
Developer utilities

And everything runs directly in the browser whenever possible.

Curious About Your Workflow

What’s the most frustrating file format issue you still deal with regularly?

For me, HEIC compatibility problems are still surprisingly common in 2026.

Error when integrating service worker into mattermost-webapp application

Trần Xuân Ái — Tue, 24 Nov 2020 10:18:33 +0000

I am integrating service worker into Mattermost-webapp.

Description:

Currently, my application is starting from
http://localhost:8065/static/ but in essence, it must start from http://localhost:8065/ to be correct.

So when starting my Pwa application, start_url is http://localhost:8065/static/ should give 404 error

Target:

I need to set start_url to http://localhost:8065/ or is there a way for my service worker to work properly, initialized from the root folder? I need a solution
Please help me

Here is my code description:

I register serviceWorker in root.jsx

if ('serviceWorker' in navigator) {
    window.addEventListener('load', () => {
        // Scope will be restricted to the path where the src-sw.js file is located
        navigator.serviceWorker.register('/static/sw.js', {scope: '/static/'}).then((registration) => {
            console.log('Service Worker registered: ', registration);
        }).catch((registrationError) => {
            console.log('Service Worker registration failed: ', registrationError);
        });
    });
}

This is webpack.config.js

// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

const childProcess = require('child_process');

const path = require('path');
const url = require('url');
const CopyWebpackPlugin = require('copy-webpack-plugin');
const webpack = require('webpack');
const nodeExternals = require('webpack-node-externals');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const WebpackPwaManifest = require('webpack-pwa-manifest');
const LiveReloadPlugin = require('webpack-livereload-plugin');
const WorkboxPlugin = require('workbox-webpack-plugin');
const NPM_TARGET = process.env.npm_lifecycle_event; //eslint-disable-line no-process-env

const targetIsRun = NPM_TARGET === 'run';
const targetIsTest = NPM_TARGET === 'test';
const targetIsStats = NPM_TARGET === 'stats';
const targetIsDevServer = NPM_TARGET === 'dev-server';

const DEV = targetIsRun || targetIsStats || targetIsDevServer;

const STANDARD_EXCLUDE = [
    path.join(__dirname, 'node_modules'),
];

// react-hot-loader requires eval
const CSP_UNSAFE_EVAL_IF_DEV = targetIsDevServer ? ' \'unsafe-eval\'' : '';

var MYSTATS = {

    // Add asset Information
    assets: false,

    // Sort assets by a field
    assetsSort: '',

    // Add information about cached (not built) modules
    cached: true,

    // Show cached assets (setting this to `false` only shows emitted files)
    cachedAssets: true,

    // Add children information
    children: true,

    // Add chunk information (setting this to `false` allows for a less verbose output)
    chunks: true,

    // Add built modules information to chunk information
    chunkModules: true,

    // Add the origins of chunks and chunk merging info
    chunkOrigins: true,

    // Sort the chunks by a field
    chunksSort: '',

    // `webpack --colors` equivalent
    colors: true,

    // Display the distance from the entry point for each module
    depth: true,

    // Display the entry points with the corresponding bundles
    entrypoints: true,

    // Add errors
    errors: true,

    // Add details to errors (like resolving log)
    errorDetails: true,

    // Exclude modules which match one of the given strings or regular expressions
    exclude: [],

    // Add the hash of the compilation
    hash: true,

    // Set the maximum number of modules to be shown
    maxModules: 0,

    // Add built modules information
    modules: false,

    // Sort the modules by a field
    modulesSort: '!size',

    // Show performance hint when file size exceeds `performance.maxAssetSize`
    performance: true,

    // Show the exports of the modules
    providedExports: true,

    // Add public path information
    publicPath: true,

    // Add information about the reasons why modules are included
    reasons: true,

    // Add the source code of modules
    source: true,

    // Add timing information
    timings: true,

    // Show which exports of a module are used
    usedExports: true,

    // Add webpack version information
    version: true,

    // Add warnings
    warnings: true,

    // Filter warnings to be shown (since webpack 2.4.0),
    // can be a String, Regexp, a function getting the warning and returning a boolean
    // or an Array of a combination of the above. First match wins.
    warningsFilter: '',
};

let publicPath = '/static/';

// Allow overriding the publicPath in dev from the exported SiteURL.
if (DEV) {
    const siteURL = process.env.MM_SERVICESETTINGS_SITEURL || ''; //eslint-disable-line no-process-env
    if (siteURL) {
        publicPath = path.join(new url.URL(siteURL).pathname, 'static') + '/';
    }
}

var config = {
    entry: ['./root.jsx', 'root.html'],
    output: {
        path: path.join(__dirname, 'dist'),
        publicPath,
        filename: '[name].[hash].js',
        chunkFilename: '[name].[contenthash].js',
    },
    module: {
        rules: [
            {
                test: /\.(js|jsx|ts|tsx)?$/,
                exclude: STANDARD_EXCLUDE,
                use: {
                    loader: 'babel-loader',
                    options: {
                        cacheDirectory: true,

                        // Babel configuration is in .babelrc because jest requires it to be there.
                    },
                },
            },
            {
                type: 'javascript/auto',
                test: /\.json$/,
                include: [
                    path.resolve(__dirname, 'i18n'),
                ],
                exclude: [/en\.json$/],
                use: [
                    {
                        loader: 'file-loader?name=i18n/[name].[hash].[ext]',
                    },
                ],
            },
            {
                test: /\.scss$/,
                use: [
                    DEV ? 'style-loader' : MiniCssExtractPlugin.loader,
                    {
                        loader: 'css-loader',
                    },
                    {
                        loader: 'sass-loader',
                        options: {
                            sassOptions: {
                                includePaths: ['node_modules/compass-mixins/lib', 'sass'],
                            },
                        },
                    },
                ],
            },
            {
                test: /\.css$/,
                use: [
                    DEV ? 'style-loader' : MiniCssExtractPlugin.loader,
                    {
                        loader: 'css-loader',
                    },
                ],
            },
            {
                test: /\.(png|eot|tiff|svg|woff2|woff|ttf|gif|mp3|jpg)$/,
                use: [
                    {
                        loader: 'file-loader',
                        options: {
                            name: 'files/[hash].[ext]',
                        },
                    },
                    {
                        loader: 'image-webpack-loader',
                        options: {},
                    },
                ],
            },
            {
                test: /\.html$/,
                use: [
                    {
                        loader: 'html-loader',
                        options: {
                            attributes: {
                                list: [
                                    {
                                        tag: 'link',
                                        attribute: 'href',
                                        type: 'src',
                                    },
                                ],
                            },
                        },
                    },
                ],
            },
        ],
    },
    resolve: {
        modules: [
            'node_modules',
            path.resolve(__dirname),
        ],
        alias: {
            jquery: 'jquery/src/jquery',
            superagent: 'node_modules/superagent/lib/client',
        },
        extensions: ['.js', '.jsx', '.ts', '.tsx'],
    },
    performance: {
        hints: 'warning',
    },
    target: 'web',
    plugins: [
        new webpack.ProvidePlugin({
            'window.jQuery': 'jquery',
            $: 'jquery',
            jQuery: 'jquery',
        }),
        new webpack.DefinePlugin({
            COMMIT_HASH: JSON.stringify(childProcess.execSync('git rev-parse HEAD || echo dev').toString()),
        }),
        new MiniCssExtractPlugin({
            filename: '[name].[contentHash].css',
            chunkFilename: '[name].[contentHash].css',
        }),
        new HtmlWebpackPlugin({
            filename: 'root.html',
            inject: 'head',
            template: 'root.html',
            title: 'Progressive Web Application',
            meta: {
                csp: {
                    'http-equiv': 'Content-Security-Policy',
                    content: 'script-src \'self\' \'unsafe-eval\' cdn.rudderlabs.com *.facebook.com *.fbcdn.net *.facebook.net *.google-analytics.com *.virtualearth.net *.google.com 127.0.0.1:* *.spotilocal.com:* ' + CSP_UNSAFE_EVAL_IF_DEV,
                },
            },
        }),
        new CopyWebpackPlugin({
            patterns: [
                {from: 'images/emoji', to: 'emoji'},
                {from: 'images/img_trans.gif', to: 'images'},
                {from: 'images/logo-email.png', to: 'images'},
                {from: 'images/circles.png', to: 'images'},
                {from: 'images/favicon', to: 'images/favicon'},
                {from: 'images/appIcons.png', to: 'images'},
                {from: 'images/warning.png', to: 'images'},
                {from: 'images/logo-email.png', to: 'images'},
                {from: 'images/browser-icons', to: 'images/browser-icons'},
            ],
        }),

        // Generate manifest.json, honouring any configured publicPath. This also handles injecting
        // <link rel="apple-touch-icon" ... /> and <meta name="apple-*" ... /> tags into root.html.

        new WebpackPwaManifest({
            name: 'ChatOps',
            short_name: 'ChatOps',
            start_url: './',
            description: 'ChatOps is Seamless Collaboration Platform',
            background_color: '#ffffff',
            inject: true,
            ios: true,
            fingerprints: false,
            orientation: 'any',
            filename: 'manifest.json',
            icons: [{
                src: path.resolve('images/favicon/android-chrome-192x192.png'),
                type: 'image/png',
                sizes: '192x192',
            }, {
                src: path.resolve('images/favicon/apple-touch-icon-120x120.png'),
                type: 'image/png',
                sizes: '120x120',
                ios: true,
            }, {
                src: path.resolve('images/favicon/apple-touch-icon-144x144.png'),
                type: 'image/png',
                sizes: '144x144',
                ios: true,
            }, {
                src: path.resolve('images/favicon/apple-touch-icon-152x152.png'),
                type: 'image/png',
                sizes: '152x152',
                ios: true,
            }, {
                src: path.resolve('images/favicon/apple-touch-icon-57x57.png'),
                type: 'image/png',
                sizes: '57x57',
                ios: true,
            }, {
                src: path.resolve('images/favicon/apple-touch-icon-60x60.png'),
                type: 'image/png',
                sizes: '60x60',
                ios: true,
            }, {
                src: path.resolve('images/favicon/apple-touch-icon-72x72.png'),
                type: 'image/png',
                sizes: '72x72',
                ios: true,
            }, {
                src: path.resolve('images/favicon/apple-touch-icon-76x76.png'),
                type: 'image/png',
                sizes: '76x76',
                ios: true,
            }, {
                src: path.resolve('images/favicon/favicon-16x16.png'),
                type: 'image/png',
                sizes: '16x16',
            }, {
                src: path.resolve('images/favicon/favicon-32x32.png'),
                type: 'image/png',
                sizes: '32x32',
            }, {
                src: path.resolve('images/favicon/favicon-96x96.png'),
                type: 'image/png',
                sizes: '96x96',
            }],
        }),

        new WorkboxPlugin.InjectManifest({
            swSrc: './src-sw.js',
            swDest: 'sw.js',
            exclude: [
                /\.map$/,
                /manifest$/,
                /\.htaccess$/,
                /service-worker\.js$/,
                /sw\.js$/,
            ],
        }),
    ],
};

if (!targetIsStats) {
    config.stats = MYSTATS;
}

// Development mode configuration
if (DEV) {
    config.mode = 'development';
    config.devtool = 'source-map';
}

// Production mode configuration
if (!DEV) {
    config.mode = 'production';
    config.devtool = 'source-map';
}

const env = {};
if (DEV) {
    env.PUBLIC_PATH = JSON.stringify(publicPath);
    if (process.env.MM_LIVE_RELOAD) { //eslint-disable-line no-process-env
        config.plugins.push(new LiveReloadPlugin());
    }
} else {
    env.NODE_ENV = JSON.stringify('production');
}

config.plugins.push(new webpack.DefinePlugin({
    'process.env': env,
}));

// Test mode configuration
if (targetIsTest) {
    config.entry = ['./root.jsx'];
    config.target = 'node';
    config.externals = [nodeExternals()];
}

if (targetIsDevServer) {
    config = {
        ...config,
        devtool: 'cheap-module-eval-source-map',
        devServer: {
            hot: true,
            injectHot: true,
            liveReload: false,
            overlay: true,
            proxy: [{
                context: () => true,
                bypass(req) {
                    if (req.url.indexOf('/api') === 0 ||
                        req.url.indexOf('/plugins') === 0 ||
                        req.url.indexOf('/static/plugins/') === 0 ||
                        req.url.indexOf('/sockjs-node/') !== -1) {
                        return null; // send through proxy to the server
                    }
                    if (req.url.indexOf('/static/') === 0) {
                        return path; // return the webpacked asset
                    }

                    // redirect (root, team routes, etc)
                    return '/static/root.html';
                },
                logLevel: 'silent',
                target: 'http://localhost:8065',
                xfwd: true,
                ws: true,
            }],
            port: 9005,
            watchContentBase: true,
            writeToDisk: false,
        },
        performance: false,
        optimization: {
            ...config.optimization,
            splitChunks: false,
        },
        resolve: {
            ...config.resolve,
            alias: {
                ...config.resolve.alias,
                'react-dom': '@hot-loader/react-dom',
            },
        },
    };
}

// Export PRODUCTION_PERF_DEBUG=1 when running webpack to enable support for the react profiler
// even while generating production code. (Performance testing development code is typically
// not helpful.)
// See https://reactjs.org/blog/2018/09/10/introducing-the-react-profiler.html and
// https://gist.github.com/bvaughn/25e6233aeb1b4f0cdb8d8366e54a3977
if (process.env.PRODUCTION_PERF_DEBUG) { //eslint-disable-line no-process-env
    console.log('Enabling production performance debug settings'); //eslint-disable-line no-console
    config.resolve.alias['react-dom'] = 'react-dom/profiling';
    config.resolve.alias['schedule/tracing'] = 'schedule/tracing-profiling';
    config.optimization = {

        // Skip minification to make the profiled data more useful.
        minimize: false,
    };
}

module.exports = config;

This is src-sw.js

"workbox-webpack-plugin": "4.3.1",
"workbox-window": "4.3.1",

if ('workbox' in self) {
    workbox.precaching.precacheAndRoute(self.__precacheManifest);

    // self.__precacheManifest

    workbox.routing.registerRoute(
        /https:\/\/api\.exchangeratesapi\.io\/latest/,
        new workbox.strategies.NetworkFirst({
            cacheName: 'ChatOpsDemoCache',
            plugins: [
                new workbox.expiration.Plugin({
                    maxAgeSeconds: 10 * 60, // 10 minutes
                }),
            ],
        }),
    );
}

addEventListener('message', (event) => {
    if (event.data && event.data.type === 'SKIP_WAITING') {
        skipWaiting();
    }
});