devkit

Developer Tools, Right in Your Browser

34 free, open-source utilities for encoding, generating, testing, and converting — all client-side. No sign-up, no tracking, no server calls.

Encoders & Parsers

View all →

Encode, decode, and parse data formats — JWT, Base64, URL, JSON, YAML, and more.

JWT Parser
Paste a token to decode header and payload locally
Query String Parser
Paste a URL to view and edit query parameters
URL Encoder / Decoder
Encode or decode URL components and full URIs
JSON ↔ YAML
Convert between JSON and YAML instantly
Base64 Encode / Decode
Encode text to Base64 or decode Base64 back to text
Markdown Preview
Write Markdown and preview the rendered HTML side by side
JSON Schema Validator
Validate JSON data against a JSON Schema with detailed error reporting
JSON Prettier / Minifier
Format, prettify, or minify JSON with configurable indentation
SQL Formatter
Format and validate SQL queries with dialect support

Generators

View all →

Generate UUIDs, passwords, hashes, cron expressions, lorem ipsum, and CSS layouts.

Cron Job Builder
Visually build and validate cron expressions
UUID Generator
Generate v4, v7 UUIDs with bulk generate and copy
Hash Generator
Generate MD5, SHA-1, SHA-256, and SHA-512 hashes
Password Generator
Generate secure passwords with configurable character sets
CSS Grid Builder
Visually design CSS grid layouts with live preview
Box Shadow Builder
Visually design CSS box-shadows with layered controls
Border Radius Builder
Fine-tune CSS border-radius with per-corner controls
Flexbox Builder
Build CSS flexbox layouts visually with live preview
Lorem Ipsum Generator
Generate placeholder text in paragraphs, sentences, or words

Testing & Validation

View all →

Test regex patterns, compare text diffs, and validate data with live feedback.

Regex Tester
Test regular expressions with live matching and groups
Text Diff Checker
Compare two blocks of text and see line-by-line differences
YAML Validator
Validate YAML syntax with line-level error reporting
Encoding Detector
Detect text encoding and view hex, byte, and code-point representations

Visual & Accessibility

View all →

Check color contrast, simulate color blindness, convert color codes, and create gradients.

Color Contrast Tester
Check WCAG color contrast ratios for accessibility
Color Blindness Simulator
Preview colors and images under different CVD types
Color Code Converter
Convert colors between HEX, RGB, HSL, HWB, and OKLCH
CSS Gradient Generator
Create linear, radial, and conic CSS gradients visually
Mesh Gradient Generator
Create mesh gradients with grain, blur, and color controls

Date & Time

View all →

Convert timestamps between formats and time zones around the world.

Time Zone Converter
Convert timestamps between formats and time zones
Date Difference
Visualize the difference between two dates in every unit
Age Calculator
See your age broken down into years, months, days, and more
Time Until Countdown
Live countdown to any future date or event
World Clock
Compare live clocks across multiple time zones side by side

Lookups

View all →

Search MIME types, HTTP status codes, and other developer reference data.

MIME Type Lookup
Search for MIME types by extension or content type
HTTP Status Codes
Browse and search HTTP status codes with descriptions

Why devkit?

100% Client-Side

Every tool runs entirely in your browser. Your data never leaves your machine — no API calls, no server processing.

Free & Open Source

No accounts, no paywalls, no ads. The source code is available on GitHub for anyone to inspect, contribute to, or self-host.

Fast & Focused

Built with Next.js, React, and Tailwind CSS for speed. Each tool is purpose-built to do one thing well with zero bloat.