Free online developer tools that run entirely inside your browser tab. Format and validate a payload in the JSON Formatter & Validator, read a live token in the JWT Decoder, convert config between formats, and check a pattern in the Regex Tester, with nothing uploaded to a server.
Start with the JSON Formatter & Validator to format and validate a payload, then flip config between formats with the YAML to JSON Converter or the JSON to YAML Converter. Shrink assets with the JavaScript Minifier and HTML Minifier, work out why a schedule misfires with the Cron Expression Parser, and hand the awkward one-off jobs to JSON Diff, the Docker Run to Compose Converter and the Git Command Generator.
The Regex Tester, Base64 Encode / Decode and URL Encode / Decode cover most of what you reach for mid-bug, alongside the Hash Generator and HMAC Generator, the UUID Generator, the Epoch Converter and Timestamp to Date Converter, the Chmod Calculator, and the HTTP Status Code Lookup and MIME Type Lookup. When you are shipping rather than debugging, the Robots.txt Generator, Sitemap Generator, Meta Tag Generator, Open Graph Preview and .htaccess Redirect Generator cover the deploy checklist.
Nothing here asks for an account, sets a tracking cookie, or posts your input to a server, which matters when the thing you are debugging is a live JWT or a customer data export. Open a tool, paste, read the result, close the tab. Switch off your wifi halfway through and everything keeps working, which is the simplest proof that the processing really is local.
It depends entirely on whether the tool processes your input in the browser or on a server. Many popular formatters and decoders POST what you paste to a backend, where it can end up in request logs. A JWT is only Base64 encoded and not encrypted, so a production token pasted into a server-side decoder should be treated as a leaked credential. These tools run client-side in JavaScript, so nothing you paste leaves the tab.
No. Each tool is an ordinary web page with all of its logic in JavaScript, so there is no account, no email wall, no free trial and no extension or desktop app to install. There is nothing to install because there is no server component to connect to. Bookmark the JSON Formatter or the Regex Tester and it opens straight into a working editor, including on a locked-down work laptop.
The practical limit is your device's memory, not a pricing tier. Because nothing is uploaded there is no 1 MB or 5 MB cap, no queue and no rate limit. Multi-megabyte JSON documents, SQL dumps and log files format fine on a normal laptop, since the browser tab does the work. Very large inputs are bounded only by available RAM and CPU, so processing may simply take a few seconds longer.