I Ship 10 Free Browser Tools a Day. Here Are 12 I Actually Use.

Eight weeks ago I started a strange routine: every day, ship 10 new free tools to a single website. No signup walls, no ads, no server-side anything. Just HTML, CSS, and JavaScript that runs entirely in the browser.

Today the catalog passed 546 tools. The pace is one batch per day, every day, and I have no plans to stop.

Before the catalog drowns in its own size, I want to point at the ones I actually open — the tools that survived daily use instead of just shipping.

The rules everything follows

Every tool on the site obeys the same constraints, which turned out to be a feature rather than a limitation:

1. Zero backend. Your data never leaves your device. There's no server to breach, no analytics on your input.
2. Instant load. No frameworks, no build step. The heaviest tool on the site is 170 KB.
3. Works offline once the page loads.
4. No dark patterns. No cookie banners, no "premium" tier, no newsletter modal.

The 12 I keep using

TOTP Generator — Time-based 2FA codes in the browser, standard RFC 6238. I use it for test accounts where I don't want to touch my phone. Same math as Google Authenticator, entirely client-side.

Hex Viewer — Drag any file in, get offsets, hex bytes, and the ASCII column, plus a per-byte inspector. 256 KB cap, which is exactly enough for "what is this header, actually."

JWT Signature Verifier — Paste a token, verify HS/RS/ES signatures offline with Web Crypto, and check exp/nbf/iat claims. Debugging auth without sending tokens to a random website is the whole point.

JSON to Kotlin — Paste a JSON response, get data classes with inferred types, nullables, and deduplicated nested classes. Saves me maybe ten minutes per API integration, which adds up.

Markdown Table to CSV — Because documentation tables should not require a text editor macro. Handles escaped pipes and alignment row stripping.

CSS Grid Generator — Edit a grid template visually, watch the live preview, copy the CSS and HTML. I stopped hand-counting grid-template-columns fractions.

Tap Tempo — Tap any key to get BPM with median outlier filtering. Niche? Extremely. The one time you need it, nothing else works.

Wordle Solver — Filter a 6,012-word list by green/yellow/gray feedback. Yes, it handles double letters correctly — that was a whole afternoon.

Enigma Simulator — A working German Enigma I in JavaScript: rotors I–V, reflectors, plugboard. The classic test vector AAAAA → BDZGO passes. Educational and weirdly fun to break codes with.

Running Pace Calculator — Pace, speed, and Riegel-based race predictions. It told me my 10K goal was unrealistic. It was right.

Ratio Calculator — The "solve for the missing value" proportions calculator. Aspect ratios, recipe scaling, mixing, whatever.

DCA Calculator — Dollar-cost averaging projection versus lump sum, weekly/monthly/yearly. The comparison chart is the honest part most investing sites skip.

How the factory works

People keep asking whether the tools are generated by AI. Here's the honest answer: yes, mostly — but not in the fire-and-forget way.

Each batch goes through a fixed pipeline:

• Dedup check against the live catalog (plus a fresh crawl of the site) — no slug collisions, ever.
• Known-answer tests. Every tool ships with test vectors checked against independent reference implementations. The Enigma simulator was validated against published vectors. The crypto tools cross-checked against node:crypto. The finance tools against plain Python.
• A validator that checks packaging, metadata lengths, zero external dependencies, and no outbound links.
• A headless-Chrome smoke test that loads each tool, clicks the sample button, and fails on any console error.

This catches real bugs constantly — just this week: a JSONPath tokenizer choking on bare < operators, a Sudoku solver that would hang forever on contradictory grids, and a CSV deduplicator that mangled RFC 4180 quoting. Shipping fast and shipping correct are not the same thing; the gates are what let me do both.

Why browser-only matters more than it sounds

The web got weird about privacy. Half the "free tools" you find upload your input to a server "for processing" — your JSON, your JWT, your file contents. For a lot of tasks there's no reason. JavaScript is fast enough for regex testing, AES-256-GCM, Boggle solving, all of it.

Every tool on the site is also trivially inspectable: view source is the whole program. If you don't trust the tool, you can read exactly what it does with your data, which is: nothing.

The catalog

If any of the above sounded useful, the full list is at minitool.io — 546 tools across text, developer utilities, and calculators, with 10 more landing every day.

And if there's a tool you keep needing that doesn't exist yet: tell me. Odds are it ships tomorrow morning.