Online developer tools
The small tools a developer opens ten times a day, in one place. Everything runs in your browser: your tokens, data and code snippets are never sent to a server.
| Tool | Category | Processing |
|---|---|---|
| JSON formatterFormat, validate and minify JSON. | Developer | In your browser |
| Base64 encoder and decoderText ↔ Base64, UTF-8 and URL-safe. | Developer | In your browser |
| JWT decoderRead a JWT's header, payload and expiry. | Developer | In your browser |
| Regex testerTest a regex with live highlighting. | Developer | In your browser |
| Number base converterBinary, octal, decimal, hex and bases 2 to 36. | Developer | In your browser |
| CSV ↔ JSON converterCSV to JSON and JSON to CSV, delimiter detected. | Developer | In your browser |
| Cron expression generator and testerCron expression explained, with its next runs. | Developer | In your browser |
| SQL formatter and minifierBeautify or minify a SQL query. | Developer | In your browser |
| JWT generator (HS256, HS384, HS512)Create and sign an HS256, HS384 or HS512 JWT. | Developer | In your browser |
| Markdown editorMarkdown with live preview and HTML export. | Developer | In your browser |
| HTML, CSS and JavaScript minifierShrink HTML, CSS or JavaScript. | Developer | In your browser |
| AES-256 encryptionEncrypt text with a password (AES-256). | Developer | In your browser |
About these tools
Formatting JSON, decoding a token, testing a regular expression, scheduling a cron job: these are actions developers repeat several times a day. These twelve tools bring them together in one place, with instant results and precise error messages.
What sets them apart: everything is computed in your browser, with JavaScript's native functions (JSON.parse, RegExp, Web Crypto, TextEncoder, Intl). Unlike many similar sites, no JWT, no API response and no code snippet is sent to a server. You can paste production data without risk of leaking it.
Results match what your code produces, since the engines are the same: a regex tested here behaves as in Node.js or Chrome, and a JWT signed here is accepted by jsonwebtoken or PyJWT with the same key.
Which tool should I use?
Reading, fixing and converting data
The “JSON formatter” validates and indents, “CSV ↔ JSON” moves data between spreadsheets and APIs, and the “SQL formatter” makes a query readable.
Encoding, decoding and encrypting
“Base64” for data and headers, “JWT decoder” to read an authentication token, “JWT generator” to sign one and “AES encryption” to protect text with a password.
Debugging and scheduling
The “Regex tester” helps you fine-tune regular expressions, the “Cron generator” explains a schedule and its next runs, and the “Number base converter” switches between binary and hex.
Documenting and publishing
The “Markdown editor” previews a README or article, and the “Minifier” shrinks HTML, CSS and JavaScript before deployment.
Frequently asked questions
Is my data sent to a server?
No. All calculations happen in your browser; you can check in the Network tab of the developer tools: no request carries your data.
Are the results identical to my language's?
For JSON, regex and signatures, the tools use the browser's standard engines: results are JavaScript's, standards-compliant. Regex flavours from other languages (PCRE, Python) differ on a few syntax points.
Can I use these tools offline?
Once the page has loaded, most work without a connection, since no calculation depends on the server.