Developer tools that never see your data
Paste a JWT, an API key or a private config file into most online tools and it travels to somebody else's server. Every tool here runs entirely in your browser — no uploads, no accounts, no limits.
JSON Formatter
Beautify, minify and validate JSON with precise error locations. Collapsible tree view, duplicate key detection and instant byte-size reporting.
LocalJWT Decoder
Inspect header, payload and signature of a JSON Web Token. Shows expiry status, issue time and remaining lifetime without ever transmitting your token.
LocalBase64 Encode / Decode
Convert text to Base64 and back, with correct UTF-8 handling for emoji and non-Latin text that trips up most converters online.
LocalHash Generator
Generate MD5, SHA-1, SHA-256 and SHA-512 checksums from text. Uses the browser's native SubtleCrypto engine plus a bundled MD5 implementation.
LocalRegex Tester
Test regular expressions against sample text with live highlighting and a full match table including capture groups and index positions.
LocalURL Encoder / Decoder
Percent-encode strings and parse query strings correctly. Distinguishes the two RFC 3986 / form-encoding variants so your URLs stop breaking.
LocalWhy "runs in your browser" actually matters
Most free online tools accept your input, send it to a server, process it there, and send the result back. That round trip is invisible, and most of the time it is harmless. But developers regularly paste content that was never meant to leave their machine:
- JSON Web Tokens carrying session claims and user identifiers
- Configuration files containing database URLs, API secrets and internal hostnames
- Request payloads with real customer records used for debugging
- Private keys and certificates being inspected before deployment
Every tool on this site is plain JavaScript executing on your own device. When you paste something here, there is no upload, no logging, and no server-side copy. You can verify this yourself: open your browser's developer tools, switch to the Network tab, use any tool, and watch the request count stay at zero.
Try it offline. Each page works with no internet connection at all once loaded. If a tool stopped working offline, it would mean your data was leaving the device — and it does not.
How we keep this free
There is no server doing the work, so there is very little to pay for. The site itself costs almost nothing to run, which is why every tool is free, unlimited and requires no registration. Display advertising keeps the lights on. We do not sell your data, and we never will — we do not have any.
Frequently asked questions
Do you log, store or transmit anything I paste into these tools?
No. Every tool is client-side JavaScript. Your input stays in the memory of your own browser tab and disappears when you close it. There is no analytics script on these pages and no form submission step.
Is there a file size limit?
The only limit is your device's memory. Since nothing gets uploaded, we have no reason to cap file size or impose daily quotas the way server-based converters do. Very large documents may simply make your browser momentarily busy while it works.
Do I need to create an account?
No accounts, no email collection, no premium tier. All six tools are fully functional for everyone, permanently.
Can I use these results commercially?
Yes. Anything you produce with these tools — formatted JSON, decoded tokens, checksums — is yours to use without attribution or restriction.
Which browsers are supported?
Any current version of Chrome, Edge, Firefox or Safari. The tools use standard Web APIs including SubtleCrypto, TextEncoder and TextDecoder, all of which have been widely available since 2017.