Free Online Developer Tools
Format, encode, decode, and test with our suite of free developer tools. Everything runs client-side — your data never leaves the browser.
JSON Formatter & Validator
Paste your JSON to instantly format, validate, and pretty-print it with proper indentation. Spot errors quickly with clear validation messages.
Use tool →Base64 Encode/Decode
Convert text to Base64 encoding or decode Base64 strings back to readable text. Essential for working with APIs, data URIs, and encoded content.
Use tool →URL Encoder/Decoder
Encode special characters in URLs or decode percent-encoded URL strings. Essential for working with query parameters, API calls, and web development.
Use tool →JWT Decoder
Paste a JSON Web Token to instantly decode and inspect its header, payload, and claims. Check expiration dates, issuers, and custom claims without any libraries.
Use tool →UUID Generator
Generate universally unique identifiers (UUID v4) with a single click. Perfect for database primary keys, API identifiers, and tracking IDs.
Use tool →Unix Timestamp Converter
Convert between Unix timestamps (epoch time) and human-readable dates instantly. Supports seconds and milliseconds. See the current timestamp in real time.
Use tool →Regex Tester
Build and test regular expressions with real-time match highlighting. See matched groups, test against sample text, and debug patterns instantly.
Use tool →HTML Entity Encode/Decode
Convert special characters to their HTML entity equivalents or decode HTML entities back to readable text. Essential for safely embedding content in HTML.
Use tool →Markdown Preview
Type or paste Markdown and see it rendered as HTML in real time. Perfect for previewing README files, documentation, blog posts, and GitHub-flavored Markdown.
Use tool →Hash Generator
Generate cryptographic hashes from any text. Supports SHA-256, SHA-1, and MD5 algorithms. All hashing happens in your browser using the Web Crypto API.
Use tool →Color Converter
Convert colors between HEX, RGB, and HSL formats with a live color preview. Enter any color in one format and instantly get the equivalent in all others.
Use tool →CSV to JSON Converter
Paste CSV data to convert it to a JSON array of objects. The first row is used as property names.
Use tool →JSON to CSV Converter
Paste a JSON array of objects to convert it to CSV format. Property names become column headers.
Use tool →Markdown to HTML Converter
Paste Markdown and get the equivalent HTML code. Supports headings, bold, italic, links, code blocks, lists, and more.
Use tool →camelCase to Text Converter
Split camelCase or PascalCase strings into readable words with spaces. Useful for making variable names human-readable.
Use tool →snake_case to Text Converter
Replace underscores with spaces and format snake_case variable names as readable text.
Use tool →JSON String Escape Tool
Escape special characters (quotes, backslashes, newlines, tabs) in a string to make it safe for JSON embedding.
Use tool →JSON String Unescape Tool
Convert escaped JSON strings (with \n, \", etc.) back to their readable form.
Use tool →HTML to Plain Text Converter
Strip all HTML markup and extract only the text content. Useful for cleaning web content and email HTML.
Use tool →XML String Escape Tool
Escape special XML characters (&, <, >, ", ') to their entity equivalents for safe XML embedding.
Use tool →CSV Column Counter
Paste CSV data to count the number of columns, rows, and see a preview of the structure.
Use tool →TSV to CSV Converter
Convert tab-separated data to comma-separated CSV format. Simply paste TSV and get CSV output.
Use tool →YAML to JSON Converter
Paste YAML markup and convert it to equivalent JSON. Basic YAML structures supported.
Use tool →JSON to YAML Converter
Paste JSON and convert it to clean YAML format.
Use tool →Regex Escape Tool
Escape special regex metacharacters (. * + ? ^ $ { } [ ] | ( ) \) so they match literally in regular expressions.
Use tool →Pixel to Rem Converter
Convert pixel values to rem units. Default base is 16px. Essential for responsive CSS development.
Use tool →Rem to Pixel Converter
Convert rem values to pixels. Default base is 16px.
Use tool →Aspect Ratio Calculator
Calculate the aspect ratio of any dimensions, or resize proportionally by entering new width or height.
Use tool →PPI Calculator
Calculate the pixel density (PPI) of any screen from its resolution and physical size.
Use tool →Download Time Calculator
Calculate how long it will take to download a file based on its size and your connection speed.
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