Skip to content

Developer Tools

JSON, XML and SQL formatters, hash generators, JWT decoders, regex testers and everyday utilities for developers.

13 tools · all free, all run in your browser

Cron Expression Generator

Build a cron schedule from plain options and read back exactly what it means in English.

Open tool

CSS Minifier

Shrink CSS by removing comments, whitespace and the last semicolon in each rule.

Open tool

CSV to JSON Converter

Turn CSV or TSV data into a clean JSON array, with automatic number and boolean detection.

Open tool

Hash Generator

Popular

Generate MD5, SHA-1 and SHA-256 hashes of any text instantly in your browser.

Open tool

HTML Formatter & Minifier

Indent messy HTML for readability or strip whitespace and comments to minify it.

Open tool

JavaScript Minifier

Strip comments and unnecessary whitespace from JavaScript to reduce file size.

Open tool

JSON Formatter & Validator

Popular

Beautify, minify and validate JSON with clear error messages and a breakdown of the structure.

Open tool

JSON to CSV Converter

Convert an array of JSON objects into CSV, ready to open in Excel or Google Sheets.

Open tool

JWT Decoder

Popular

Decode a JSON Web Token to inspect its header, payload, expiry and claims — without sending it anywhere.

Open tool

Regex Tester

Popular

Test a regular expression against sample text and see every match, capture group and position.

Open tool

SQL Formatter

Format SQL queries with consistent keyword casing and line breaks so they are easy to review.

Open tool

Text Diff Checker

Compare two blocks of text line by line and see exactly what was added, removed or changed.

Open tool

XML Formatter

Indent and tidy XML, RSS or SVG markup so nested structures are easy to read.

Open tool

These are the everyday utilities that sit between writing code and shipping it: pretty-printing an API response, checking a regular expression against real input, decoding a JWT to see why an request is being rejected, or converting a CSV export into JSON. All of them run entirely in your browser, which matters more here than anywhere else on the site — you can paste a production payload, an access token or a proprietary query without it leaving your machine or appearing in someone else's logs.

Formatters and validators

Minified JSON, a single-line SQL query or a compressed XML document are all valid but unreadable. Formatting restores the structure so you can see nesting, spot the missing bracket and read a diff properly. The JSON formatter doubles as a validator: because it parses before it prints, a syntax error surfaces immediately with the position and reason, which is usually faster than hunting for a trailing comma by eye.

Inspecting tokens and hashes

A JWT is three Base64URL segments, and its payload is encoded rather than encrypted — anyone holding the token can read the claims. Decoding one locally is the quickest way to check an expiry time or an audience mismatch. Hashing is the opposite operation: one-way, deterministic and useful for integrity checks. MD5 and SHA-1 remain useful as checksums but are broken for security purposes, and neither should ever be used to store passwords.

Testing patterns and comparing versions

A regex that works on one example often fails on the next, so testing against a realistic block of text — with every match, index and capture group visible — catches problems before they reach production. Similarly, a line-by-line diff built on the same longest-common-subsequence approach as git makes it obvious what actually changed between two versions of a config file, a log or a block of code.

Developer Tools — questions

Is it safe to paste production data into these tools?
The processing itself is safe: nothing is uploaded, and there is no backend to log it. As a matter of habit, though, prefer expired or test credentials where you can, since anything on your clipboard can be captured by other software on your machine.
Do these tools work offline?
Once a page has loaded, the tool itself runs without a network connection because all the logic is already in your browser.
Why does the JavaScript minifier produce larger output than my build tool?
It only removes comments and whitespace. Production minifiers such as Terser, esbuild and SWC also rename variables and eliminate dead code, which saves considerably more.
Which regex flavour does the tester use?
It uses your browser's built-in ECMAScript engine, so behaviour matches JavaScript exactly, including lookbehind and named capture groups in modern browsers.

Other categories