Every developer has that moment: you need a DNS record checked, a color pair validated, a JSON string eyeballed — and the first three search results are "free tools" that want an account, a credit card, or an upload of whatever you're working on.
I run toolfyra.com, a collection of free browser tools I built partly out of frustration with exactly that pattern. This post is the developer-flavored subset of that collection: 17 tools I keep in my own bookmark bar. Everything runs client-side, nothing asks you to sign up, and I'll note where each tool stops being the right answer.
Here's the list, grouped by what you'd actually use them for.
Network & DNS
DNS Lookup — Query A, AAAA, MX, TXT, CNAME and NS records for any domain, from your browser. Useful when a DNS change "hasn't propagated" and you want to see what each record actually resolves to, without opening a terminal or hitting a rate-limited web tool that wants your email.
Internet Speed Test — Quick down/up check when a deploy "feels slow" and you want to rule out your own connection before blaming the CI runner.
Design & Frontend
Color Contrast Checker — Paste two colors, get the WCAG contrast ratio and pass/fail for AA/AAA at normal and large text sizes. I built this after one too many "the gray-on-gray looks fine to me" debates. It doesn't feel fine to 8% of your male users.
Favicon Generator — Drop in an image, get the icon set sized for modern browsers. Nothing fancy, and that's the point: it does the one boring job and gets out of the way.
QR Code Generator and Link QR Generator — Two flavors of the same job: turn a URL into a scannable QR code locally. Handy for testing mobile flows — generate a QR of your localhost tunnel URL and scan it instead of typing a 60-character ngrok address on your phone.
Text & Data
Markdown Previewer — Paste markdown, see it rendered, copy it back out. Useful for README drafts and dev.to posts themselves, before you commit them anywhere.
Text Similarity Checker — Compare two blocks of text and get a similarity score. I use it to sanity-check paraphrased docs sections and to make sure two "rewritten" paragraphs aren't secretly the same paragraph.
AI Text Detector — A heuristic check for AI-flavored prose. Treat it as a signal, not a verdict — no detector is a judge — but it's useful for a quick gut-check on copy that reads suspiciously smooth.
OCR Text Extractor — Pull text out of screenshots and photos, processed in your browser. Great for "the error message is in this screenshot and I need to grep it."
Reverse Text — Exactly what it says. Occasionally the correct tool for a palindrome test, a puzzle, or a very specific kind of debugging.
Text-to-Speech — Paste text, hear it read back. I use it to proofread: my ears catch run-on sentences my eyes skip.
Everyday Utilities
AI Token Counter — Estimate token counts for a prompt before you paste it into an API. Not model-exact, but close enough to know whether you're at 400 tokens or 4,000, which is the difference that actually matters for cost and context limits.
Pomodoro Timer — A clean 25/5 timer in a tab. I wrote about the surprising data behind pomodoro search results before; the tool itself is deliberately boring.
Typing Speed Test — WPM and accuracy. Destructive to your ego, constructive to your PR turnaround time.
Coin Flip, Wheel Picker and Yes/No Picker — Three tools for the same human problem: decisions that don't deserve a meeting. I keep them grouped because "pick one at random and move on" is a legitimate engineering strategy for reversible choices.
The honest fine print
These are single-purpose tools, not platforms. There's no history, no sync, no collaboration — if you need those, you need a real product, and some of these categories have excellent paid ones. What you get instead is: no account, no upload, no "free tier" that changes under you. The files you process and the text you paste are handled in your browser.
The full catalog is at toolfyra.com, organized by category (there's a dev tools hub that groups most of the above). If you bookmark just one thing, make it the hub — I'd rather you have the whole shelf than one screwdriver.
Disclosure: toolfyra.com is my own project. This is part of an ongoing series about building it — the earlier posts cover things like shipping ffmpeg.wasm in production and what "runs in your browser" actually means.
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