Like every developer, I have a graveyard of bookmarked "online tools." One site to format JSON, another to generate a password, a third to count words, a fourth to convert a timestamp. Each one slow, ad-heavy, and — the part that always bugged me — quietly posting whatever I paste to some server I know nothing about.
That last bit is the thing most people never think about. You paste an API response into a "free JSON formatter," and you have no idea whether that payload (tokens and all) just got logged on someone's backend. For a quick scratchpad tool, that's a weird amount of trust to hand a stranger.
So I built ToopTools — a collection of 200+ small utilities with one hard rule: everything runs client-side. Your data never leaves your browser.
The one constraint that shaped everything
The rule sounds simple, but it's actually a strong design constraint: if a tool can't run entirely in the browser, it doesn't get built.
That means:
- No backend processing. Formatting, encoding, hashing, converting — all of it happens in JS on your machine.
- No accounts, no database. There's nothing to store, because I never receive your input in the first place.
- Verifiable, not just promised. Open DevTools → Network tab, run any tool, and watch it stay empty. That's the whole pitch, and you can check it yourself instead of taking my word for it.
It's a nice property to be able to say "I literally cannot leak your data, because it never reaches me."
The stack
Nothing exotic, on purpose:
- Next.js for the app and per-tool pages
- Vercel for hosting
- Each tool is a self-contained client component — pure functions doing the actual work
- A personalized workspace where you can pin the tools you use most, so you're not re-searching "json formatter" every single day (this is the part I use the most myself)
Some of the tools devs seem to reach for
- JSON formatter / validator
- Base64 encode / decode
- Password generator
- Hash & UUID generators
- Case converter (camel / snake / kebab / etc.)
- QR code generator
- ...and a long tail of converters and calculators
What I'm still figuring out
A few things I'd genuinely love input on:
- Discoverability of the workspace. Most people land on a single tool from search and never realize they can build a pinned workspace. How would you surface that without being annoying?
- Which tools are actually worth adding next? I have a list, but I'd rather build what people reach for than guess.
- Trust signaling. Is the "open your Network tab and check" framing convincing, or does it need something more concrete (like a visible "runs offline" badge)?
If you've built something similar, or you just have opinions on client-side-everything as an architecture, I'm all ears. And if you want to kick the tires: tooptools.com — no signup, and you can confirm the privacy claim in about ten seconds.
Happy to answer anything about the build in the comments. 👇