Best Free Developer Tools

01 · JSON Formatter

JSON Formatter

Paste ugly JSON, get pretty JSON — with syntax errors highlighted. The workhorse of every backend dev's bookmarks bar.

02 · Regex Tester

Regex Tester

Test regex against real input, see matches highlighted, export to JavaScript, Python, or PHP syntax.

03 · Password Generator

Password Generator

Generate a strong random password with configurable length and character classes — never use the 'admin123' default again.

04 · UUID Generator

UUID Generator

Generate UUID v4 in bulk — useful when seeding test data or stubbing IDs in a fixture file.

05 · Base64 Encoder & Decoder

Base64 Encoder & Decoder

Encode/decode Base64 in both directions. Handles URL-safe variants and file uploads.

06 · JWT Decoder

JWT Decoder

Paste a JWT, see the header and payload decoded — without sending the token to someone else's server.

07 · HTML Formatter

HTML Formatter

Pretty-print an HTML blob, including inline CSS and JS, with configurable indent.

08 · SQL Formatter

SQL Formatter

Format a SQL query across multiple dialects (Postgres, MySQL, SQLite, SQL Server). Makes code review readable.

09 · Hash Generator

Hash Generator

Generate MD5, SHA-1, SHA-256, SHA-512 hashes of any input string — in your browser, no round-trip.

10 · Cron Expression Builder

Cron Expression Builder

Build a cron expression with a visual picker, see the next five runs, copy into crontab or a scheduler config.

11 · URL Encoder & Decoder

URL Encoder & Decoder

URL-encode or decode any string, including special characters and Unicode. Useful when debugging redirects.

12 · Diff Checker

Diff Checker

Paste two blobs of text, see a side-by-side diff. No git required, no repo, just the diff.

13 · HTTP Status Code Lookup

HTTP Status Code Lookup

Look up any HTTP status code with a plain-English meaning and a 'what to do about it' note.

14 · MIME Type Lookup

MIME Type Lookup

Look up the MIME type for any file extension, or the reverse — what extension fits a MIME type.

15 · Gitignore Generator

Gitignore Generator

Build a .gitignore from common stacks (Node, Python, macOS, Windows, JetBrains) in two clicks.

16 · JSON to TypeScript Interface

JSON to TypeScript Interface

Paste a JSON blob, get a TypeScript interface — saves ten minutes every time you integrate a new API.

17 · Regex Builder

Regex Builder

Build a regex by checking off what you want to match — no memorizing lookaheads and character classes.

18 · CSS to Tailwind

CSS to Tailwind

Paste raw CSS, get the equivalent Tailwind utility classes. Useful when converting a legacy stylesheet.