I Built 107 Free Browser-Based Tools as a Solo Developer — Here's What I Learned

When I started building Cookies & Cursor, my goal was simple: create a collection of genuinely free tools that don't require signup, don't track users, and actually work.

Three months later, I have 107 tools live across 15 categories. Here's what I learned building them as a solo developer.

What I built

The tools cover:

Finance calculators (mortgage, compound interest, loan, retirement, FIRE)
Developer utilities (JSON formatter, regex tester, base64 encoder, SQL formatter, crontab generator)
SEO tools (meta tag generator, robots.txt generator, schema generator)
Health calculators (BMI, BMR, body fat, macro calculator)
Text tools (case converter, word counter, diff checker, markdown to HTML)
Document generators (invoice, rent receipt, salary slip)
And more across 15 categories

Everything runs client-side — no server processing, no data sent anywhere.

What I learned

1. Consistency matters more than perfection
   Every tool follows the same template — same layout, same JSON-LD schema, same FAQ structure. Users instantly know what to expect. Building a template first saved hundreds of hours.

2. "Try Example" button is underrated
   I added a one-click "Try Example" button to every tool. It pre-fills realistic sample data so users immediately see the tool working. Bounce rate dropped noticeably after adding this.

3. Client-side only has real limits
   Some tools I wanted to build — like a live SEO analyzer or grammar checker — genuinely need a server. Knowing this upfront saved me from half-building things that couldn't work.

4. Related tools matter
   Each tool links to 3-4 related tools. A user on the mortgage calculator sees links to the loan calculator, compound interest calculator, and retirement calculator. This keeps users on the site longer.

What's next

Still working on getting the tools indexed by Google — domain authority takes time to build. Currently at DR 0 with minimal legitimate backlinks. Being honest about that.

If you've built something similar or have thoughts on growing a tools site, I'd love to hear it in the comments.

Check it out: cookiescursor.com/tools