Free online developer tools
53 browser-based tools. JSON formatter, Base64, URL encoder, string diff, px to rem, and more. No login, no tracking, no server.
Base64
Encode and decode Base64 strings quickly.
URL Encoder
Encode and decode URLs for web applications.
JWT Debugger
Decode and verify JSON Web Tokens (JWT) instantly.
Timestamp
Convert between timestamps and human-readable dates.
String Case
Convert text between different case formats.
Color Hex
Generate and convert color hex codes.
String Diff
Compare two strings and see their differences.
JSON Editor
Edit, format, and validate JSON data with syntax highlighting.
Image to Base64
Convert images to base64 strings.
Base64 to Image
Convert base64 strings back to images.
JSON Formatter
Format, validate, and minify JSON data with syntax highlighting.
Hash Generator
Generate MD5, SHA1, SHA256, and SHA512 hashes from text.
CSS Gradient
Build linear, radial, and conic gradients with live preview.
HTML Viewer
View and preview HTML with CSS and JS live in your browser.
UUID Generator
Generate random UUID v4 strings in bulk. Copy one or all.
Random String
Generate secure random strings for API keys and passwords.
Number Base
Convert numbers between binary, octal, decimal, and hex.
Regex Tester
Test regular expressions with real-time match highlighting.
JSONL Validator
Validate JSON Lines and convert valid records to a JSON array.
Query Params → JSON
Parse URL query parameters into a structured JSON object.
Lorem Ipsum
Generate placeholder text by paragraphs, sentences, or words.
CSV to JSON
Convert CSV data to a JSON array. Supports headers and custom delimiters.
JSON to CSV
Convert a JSON array of objects to CSV format.
TSV to JSON
Convert tab-separated values to JSON. Paste directly from Excel.
JSON to TSV
Convert JSON to tab-separated values for Excel or Google Sheets.
XML to JSON
Convert XML to JSON. Handles nested elements and attributes.
CSV Viewer
View, search, and sort CSV files as a table. Drag and drop to load.
CSS Minifier
Minify CSS to reduce file size or beautify minified code for readability.
px → rem
Convert pixel values to rem and back with a configurable base size.
Contrast Checker
Check color contrast ratios against WCAG AA and AAA accessibility standards.
Box Shadow
Build CSS box shadows visually with sliders and copy the generated code.
JS Runner
Run JavaScript snippets in a secure sandbox — no DevTools needed.
Age Calculator
Calculate exact age in years, months, and days with a birthday countdown.
Border Generator
Generate CSS borders visually — width, style, color, and radius per side.
SVG Editor
Write and preview SVG markup in real time. Insert shapes, load presets, download.
JSON Escape
Escape raw text into a JSON-safe string or unescape a JSON string back to plain text.
User Agent Parser
Decode any User-Agent string to browser, engine, OS, and device type instantly.
Binary Translator
Convert text to binary code and binary back to text instantly.
Phone Number Generator
Generate random fake US phone numbers in multiple formats for testing.
Number to Words
Convert whole numbers into English words.
SQL Formatter
Format SQL queries for easier reading.
Source Code Viewer
View source code with line numbers.
XML Viewer
Format and inspect XML markup.
Encryption-Decryption
Encrypt and decrypt text locally with a key.
Excel to HTML
Convert spreadsheet rows into an HTML table.
CSS Validator
Run quick CSS syntax checks.
XML Validator
Validate XML markup in the browser.
JavaScript Validator
Check JavaScript syntax without executing code.
ASCII to Text
Convert ASCII codes to text and back.
Random Emoji
Generate random emoji in bulk.
Incorrect Quotes
Generate playful dialogue snippets from names.
Lua Beautifier
Beautify Lua code with simple indentation.
HEX to Colortone
Generate tints and shades from a HEX color.
From the blog
All articlesBase64 Encoding: A Complete Developer Guide
From basic concepts to advanced use cases in web development and API communication.
JWT Token Debugging: Common Issues & Fixes
Decode, verify, and troubleshoot JSON Web Tokens with practical debugging techniques.
JSON Best Practices for Modern APIs
Structure, validate, and document JSON data for cleaner, more maintainable APIs.
Hash Algorithms: MD5 vs SHA — Which to Use?
A practical guide to choosing the right hashing algorithm for security and data integrity.
URL Encoding: The Complete Reference
Everything you need to know about percent-encoding and when to apply it correctly.
Unix Timestamps: Conversion & Timezone Handling
Work confidently with epoch time, timezones, and date formatting across platforms.