I keep bookmarking web tools and then forgetting where I saved them. So I started collecting the ones I actually use into a single page.
Here are 10 that I reach for constantly — all free, all run in-browser, no signup needed.
Developer Tools
1. JSON Formatter & Validator
Paste JSON, get it pretty-printed with syntax highlighting. More importantly: it tells you exactly where the error is, with line and column numbers. Better than most VS Code extensions for quick validation.
2. Base64 Encoder/Decoder
Text, files, and JWTs. The JWT decode mode saves me from going to jwt.io every time I need to inspect a token. Drag-and-drop file encoding is a nice touch.
3. AI Token Counter
Paste a prompt, see estimated token counts for GPT-4o, Claude, and Llama. Shows cost estimates too. Essential if you're building anything with LLM APIs and trying to stay under budget.
4. Link Preview Checker
See how your Open Graph tags will render on Google, Twitter, Discord, WhatsApp, LinkedIn, Slack, and iMessage — all at once. Saves you from deploying, sharing to a test channel, deleting, and repeating.
5. QR Code Generator
No watermark, no email, no "premium tier." Just paste text, get a QR code, download as PNG.
Productivity Tools
6. Word Counter
Words, characters, sentences, paragraphs, reading time. I use this for blog posts and documentation where length matters.
7. Unit Converter
Length, weight, temperature, speed, area, volume. Shareable conversion URLs — handy for Slack messages.
Fun / Challenge Tools
8. Reaction Time Test
Tap when the screen turns green. Average is 250ms. My best is 214ms. There's a challenge link feature — I've started a minor war in my team's Slack.
9. Typing Speed Test
Real text passages, not random words. WPM + accuracy. Also has challenge links.
10. Daily Math Puzzle
Combine 6 numbers to reach a target. New puzzle every day. Basically Countdown (the British game show) in your browser. Warning: addictive.
All of these are on one page if you want to bookmark just one thing: billion-hub.pages.dev
What browser tools do you use daily? Always looking for more to add.
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