From Excel Sheets to a Full Trading Terminal: How I Built MulMarket as a Solo Developer

Manpi — Sat, 21 Feb 2026 15:06:56 +0000

A while ago I got into CS2 skin trading casually. I wasn’t trying to become a full-time trader — I was mostly curious about how prices move and whether small arbitrage opportunities actually exist.

What surprised me wasn’t the market itself, but how messy the workflow was.

Every time I wanted to evaluate a single skin, I had to open multiple marketplace tabs, manually compare prices, calculate fees, and still never be completely sure if something was truly profitable.

It felt less like trading and more like repetitive admin work.

My first “solution”: spreadsheets

Before writing a single line of code, I tried solving the problem with Excel.

I built several spreadsheets to:

track prices manually

calculate ROI after fees

monitor potential profit margins

For a while, this worked.

But the more I used them, the more obvious the limitations became:

data had to be updated manually

I still missed opportunities

the workflow was slow and error-prone

At some point I realized I was spending more time maintaining spreadsheets than actually analyzing the market.

That’s when I decided to automate it.

Building the first version

I started developing a small desktop tool just for myself.

The goal was simple:

See all relevant market data in one place and instantly understand profitability.

The first version was extremely basic, but it already solved a major problem — it removed the need to constantly switch between tabs and manually calculate margins.

Once I started using it daily, something interesting happened.

It began to snowball.

How it grew into a full system

Every time I ran into a new frustration while trading, I added a feature to solve it.

Over time the tool evolved to include:

live price tracking across multiple markets

automatic ROI calculations after fees

arbitrage opportunity detection

historical price trend analysis

inventory value tracking

customizable analytics dashboards

What started as a simple automation script slowly turned into a full analytics terminal for CS2 skin trading.

The unexpected challenge: support as a solo dev

Once I shared the tool with friends and other traders, I realized another problem:

Support.

As a solo developer, I couldn’t realistically be available 24/7 to answer questions.

So I built an AI support system on Discord that can handle common user questions and guide new users even when I’m offline.

This turned out to be one of the most important decisions for keeping the project sustainable.

Privacy-first by design

Another decision I made early was to keep the tool privacy-friendly.

MulMarket runs locally on the user’s machine and doesn’t collect personal data.

This also meant avoiding ad-based monetization models.

Free vs Pro version

I released a free version so users could try the tool without commitment.

The Pro version exists mainly to help cover infrastructure costs like servers, hosting, and ongoing development — since I’m working on the project alone.

Lessons learned

Building this project taught me several important things:

Real problems make the best project ideas.

Spreadsheets are often the first step before automation.

Solo development requires thinking about sustainability early.

Support systems are just as important as the product itself.

Final thoughts

It’s been fascinating watching something that started as personal frustration and a few Excel sheets gradually evolve into a full analytics tool used by other traders.

If you’re curious, you can check it out here:

👉 https://mulmarket.store

I’d love to hear feedback or discuss similar experiences — especially if you’ve ever turned a simple workaround into a real project.

Forem: Manpi

From Excel Sheets to a Full Trading Terminal: How I Built MulMarket as a Solo Developer