About LocalBox Tools
LocalBox Tools is a small collection of free online utilities for developers. The guiding idea behind every tool here is straightforward: the work should happen on your machine, not ours.
The problem we wanted to solve
Developers constantly need to format a JSON payload, peek inside a JWT, verify a checksum or test a regular expression. The internet offers endless free tools for this, and nearly all of them work the same way — your input goes to their server, gets processed there, and comes back.
That round trip is invisible and usually harmless, but developers paste things that were never meant to leave their machine: session tokens, database URLs, production API keys, real customer records being used to reproduce a bug. Once data reaches someone else's server, you are relying on their retention policy and their goodwill.
The alternative already exists in your hands. Modern browsers are more than capable of parsing JSON, computing SHA-256, running regular expressions and manipulating encodings. When a tool ships as plain JavaScript with no server call, there is simply nothing to leak.
How the tools are built
- No frameworks. The pages are hand-written HTML, CSS and JavaScript, so they load fast even on a slow connection.
- No external resources. No CDN scripts, no web fonts, no analytics bundles. Every file is served from this domain.
- No accounts. There is nothing to sign up for, because there is no per-user state to keep.
- No upload endpoint. There is quite literally no server route that could receive your data.
- Standard Web APIs only.
crypto.subtle,TextEncoderandTextDecoderdo the heavy lifting, so results match what your own production code produces.
Verify it yourself. Open your browser's developer tools, switch to the Network tab, use any tool on this site, and watch the request counter stay at zero — other than the page's own assets. Each tool also keeps working after you disconnect from the internet.
Why it is free
Because there is barely anything to pay for. A site with no server-side computation has negligible running costs, so every tool can stay free and unlimited without a premium tier. Display advertising covers the remaining expense. We do not sell data about you, partly because that would defeat the entire point of the site, and partly because we never collect it in the first place.
Accuracy and limitations
These tools aim to be correct and dependable, but they are provided without warranty of any kind. Always verify critical output independently, particularly anything touching security, payments or legal obligations. If you spot a bug or a wrong result, please get in touch — reports from real users are how these tools get better.