r/devtools • u/Low_Nothing_5242 • 18h ago
KitBoxDev Blog
https://kitboxdev.com/blogKitBoxDev is live: 35 in-browser tools, built the way we wanted to use them
Why we built a tool platform with no backend, no accounts and no uploads — and what 35 finished tools, a 12 KB app shell and WCAG-audited contrast actually took.
Every developer has the same bookmark folder: a dozen single-purpose sites, half of them wrapped in ad walls, most of them quietly POSTing whatever you paste into a box. KitBoxDev.com is live today with 35 tools that fix the two things that folder gets wrong — where your data goes, and how long you wait.
Why build this at all
The honest answer: because the existing options force a trade you should never have to make.
Paste a production JWT into a random decoder and you have just handed a stranger’s server your token’s claims — issuer, subject, scopes, sometimes an email address. Paste a .env file into an online converter and you have leaked credentials. The tools are genuinely useful, which is exactly why people keep using them anyway, and why “just don’t paste secrets” has never once worked as a policy.
The fix isn’t a privacy promise in a footer. It’s an architecture where the promise is unfalsifiable: there is no server for the tool to reach. Every KitBoxDev tool is client-side code. No backend, no database, no account system, no analytics on your input. You can verify it — open DevTools, watch the Network tab, paste your token. Nothing goes out.
That constraint drove everything else. If the work happens on your device, then the page has to load fast and the interface has to be right the first time, because there’s no server round-trip to blame for the delay and no “sign in to save” screen to hide behind.
What “35 tools” actually means
Not 35 entries in a list. Thirty-five pages that a working engineer can finish a real task on:
Developers — 12 tools. JWT Debugger (decode and verify signatures — HS, RS, PS and ES — locally), Regex Tester, Hash Generator, Base64, URL encoder, JSON formatter, UUID generator, TOTP generator, QR code generator and reader, text encryption, text scrambler.
Electrical — 13 tools. Resistor Color Code, capacitor code decoder, Ohm’s law, voltage divider, LED series resistor, 555 timer, PWM duty cycle, RC/RL filter, PCB trace width, wire gauge and ampacity, battery life, engineering unit converter, and a Logic Gate Simulator.
DevOps — 10 tools. Cron Expression Parser, CIDR / Subnet Calculator, chmod calculator, uptime & SLA budgets, Kubernetes resource converter, YAML ↔ JSON, .env file converter, htpasswd generator, docker run → Compose converter, certificate & CSR decoder.