What I learned building my first side project: doing everything client-side

Soo — Sun, 14 Jun 2026 12:55:13 +0000

I built a website with no backend at all — every tool runs in your browser, so your data never leaves your device.

It's the first thing I've ever shipped, and honestly? I'm not sure I made the right call.

I'd love for you to tell me. 👇

The annoyance that started it

You know the loop.

You need to format a chunk of JSON. Or decode a JWT to check what's inside. Or shrink an image before uploading it somewhere.

So you Google it, click the first result, and land on a site that's:

🧱 buried in ads
🔒 asking you to "sign up to continue"
😬 telling you to "upload your file to our server" — for something that obviously doesn't need one

That last one always bugged me. Why does compressing a PNG require anyone's server?

So I built Utilify: the small tools I reach for daily, in one clean place.

I gave myself one hard constraint:

Every tool runs 100% in the browser. No backend. Ever.

Turns out the browser can already do almost all of it:

Decoding a JWT payload? It's genuinely one line:

const payload = JSON.parse(atob(token.split('.')[1]));

No request. No upload. Nothing for me to log, leak, or get hacked out of.

I went backend-less for privacy. But it quietly fixed three other things:

One decision, four wins. That rarely happens.

I couldn't fake my way through the topics — I had to understand them. A few things that surprised me enough to write up:

👉 Base64 is encoding, not encryption — and people mix this up constantly
👉 Base64 vs Base64URL — two characters (+ / vs - _) cause a shocking amount of pain
👉 How to decode a JWT in JS — and why you should never trust an unverified one

This is my first shipped project, so I'd love a reality check from people who've done this more than once:

Is "no backend" a feature users actually care about — or just a thing I find satisfying?
Canvas image compression is fine, not amazing. Is WASM worth the complexity for a free tool?
How do you know a tool is done vs. just endlessly polishing?

The JSON formatter and JWT decoder get the most use so far. Free, no signup.

If you've shipped something like this, be blunt in the comments — that's the whole reason I'm posting instead of sitting on it.

And the question I keep coming back to:

What tiny utility do you keep wishing existed in one clean, fast place? That's how I pick what to build next. 👇