Every couple of weeks I pull our usage numbers and look at what people actually reach for. The top of the list is boring in the best way: image compressor, PDF merge, QR code generator, JSON formatter. Same shape every month.
The interesting part is the middle of the list. There's a long tail of small tools that get 500 to 2,000 uses a week each — never viral, never front-page — because a specific person really needed that specific thing and told two friends. Those tools are the personality of the site, and most people never scroll far enough to find them.
So here are ten of my favourites, in no particular order, with the story of how each one earns its keep.
1. Reaction Time Test
Twenty seconds long. Click when the screen turns green. Average human reaction time is around 250 ms; a well-rested one is closer to 200 ms; if you're above 320 ms, you probably need water and a walk.
I use it as an unlisted "am I fit to keep coding?" checkpoint at 4pm. It also turns out to be a great party game with kids.
2. Midpoint Calculator
Two coordinates in, midpoint plus distance plus slope out, with the actual formulas rendered above the answer. It's aimed at students, and the emails we get from parents who "finally understood what the tuition teacher was skipping" are some of the best mail we receive.
3. Small Text Generator
Unicode has superscript letters and small caps built in. This tool lets you paste any text and get back the small version. People use it for Twitter bios, Instagram captions, aesthetic Discord names. It's Unicode, not an image, so it's still selectable, searchable and screen-reader friendly.
4. Duotone Photo Effect
Two colours, one photo. It's the aesthetic every design magazine used in 2018 and every startup pitch deck uses in 2026. A photographer friend uses it to make LinkedIn headers that don't look like everyone else's LinkedIn header.
5. Signature Maker
Draw with a mouse or trackpad, or type your name in a signature-style font. Export a transparent PNG or an SVG. Combined with our PDF Signer, this is how a lot of first-time freelancers close their first client contract without printing anything.
6. Mesh Gradient Generator
Modern gradient backgrounds — the kind Stripe and Linear use — but generated live in the browser and exportable as a PNG or CSS. Great for slide decks, YouTube thumbnails, and hero sections when you want something warm that isn't a stock photo.
7. Timestamp Link Builder
Paste a YouTube URL, scrub to the moment you want, get a shareable ?t= link. Sounds trivial. It saves me maybe five minutes a day and I use it constantly to send friends the exact bit of a podcast that made me laugh.
8. Pig Latin Translator
Surprisingly, our biggest spike in traffic every August is from parents whose kids have "code a secret language" homework. Pig Latin is the classic. It's also a nice, small demo of how real translators handle vowels, consonant clusters and punctuation.
9. Zakat Calculator
Zakat is the annual charitable payment obligatory for practising Muslims — 2.5% of qualifying wealth held for a year. Our calculator handles cash, gold, silver, business assets and debts, follows the classical rules, and shows its working. No account, no data leaves the browser.
It's a small tool with a very specific audience, and every year around Ramadan we see it get used tens of thousands of times.
10. Regex Tester
Live-highlights matches as you type, groups captures, and includes a friendly cheat sheet you don't have to click to expand. I keep it open in a pinned tab whenever I'm cleaning data.
What they have in common
None of these tools uploaded anything to a server while you were reading this paragraph. All of them work on a phone. All of them are readable by an eleven-year-old, and none of them charge money.
That's the shape of every tool on Bluebird. If a tool ever needs to break one of those rules to work, we don't ship it. So far, we haven't had to.
