Free Online Developer Tools
Format, validate, convert and inspect the data formats you work with every day. Everything runs client-side, so you can paste a staging payload without it reaching anyone else’s server.
All Developer Tools (61 Available)
Data Storage Converter
Convert bytes, KB, MB, GB, TB and their binary equivalents.
JSON Formatter
Format, validate and explore JSON with precise error reporting.
JSON Validator
Check whether JSON is valid and get the exact error position.
JSON Minifier
Strip whitespace from JSON to make it as small as possible.
JSON to CSV Converter
Turn a JSON array into a spreadsheet-ready CSV.
CSV to JSON Converter
Convert CSV or spreadsheet data into clean JSON.
JSON to YAML Converter
Convert JSON into readable YAML for configuration files.
YAML to JSON Converter
Convert YAML configuration into JSON.
YAML Formatter
Tidy and validate YAML with consistent indentation.
XML Formatter
Pretty-print and validate XML with proper indentation.
XML Validator
Check XML for well-formedness and locate errors precisely.
Base64 Encoder
Encode text to Base64, with UTF-8 and URL-safe support.
Base64 Decoder
Decode Base64 back to readable text, standard or URL-safe.
URL Encoder
Percent-encode text for safe use in URLs and query strings.
URL Decoder
Decode percent-encoded URLs back into readable text.
HTML Encoder
Escape HTML special characters to display code safely.
HTML Decoder
Convert HTML entities back into normal characters.
JWT Decoder
Decode a JSON Web Token and inspect its header and claims.
UUID Validator
Check whether a UUID is valid and identify its version.
Regex Tester
Test regular expressions live with highlighted matches and groups.
Hash Generator
Generate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes.
SHA-256 Generator
Generate a SHA-256 hash from any text.
SHA-512 Generator
Generate a SHA-512 hash from any text.
MD5 Generator
Generate an MD5 checksum — for integrity, never for security.
HTML Formatter
Beautify or minify HTML with correct indentation.
HTML Minifier
Compress HTML by removing safe whitespace and comments.
CSS Formatter
Beautify CSS with consistent indentation and spacing.
CSS Minifier
Compress CSS by stripping whitespace and comments.
JavaScript Formatter
Beautify JavaScript, TypeScript and JSX code.
SQL Formatter
Format SQL queries into readable, consistently indented statements.
SQL Minifier
Collapse a SQL query onto a single compact line.
Colour Converter
Convert between HEX, RGB, HSL, HSV and CMYK.
HEX to RGB Converter
Convert a hex colour code to RGB values.
RGB to HEX Converter
Convert RGB values to a hex colour code.
RGB to HSL Converter
Convert RGB values to hue, saturation and lightness.
HSL to RGB Converter
Convert hue, saturation and lightness to RGB and hex.
Cron Expression Generator
Build a cron schedule visually and get the expression.
Cron Expression Explainer
Paste a cron expression and read what it actually does.
User Agent Parser
Break a user agent string into browser, OS and device.
What Is My IP Address
See the public IP address your connection presents.
HTTP Status Code Lookup
Search every HTTP status code with what it means and when to use it.
MIME Type Lookup
Find the MIME type for any file extension, and vice versa.
Number Base Converter
Convert numbers between binary, octal, decimal, hex and any base.
Binary to Decimal Converter
Convert binary numbers to decimal with the working shown.
Decimal to Binary Converter
Convert decimal numbers to binary with the division steps.
Hex to Decimal Converter
Convert hexadecimal numbers to decimal.
Decimal to Hex Converter
Convert decimal numbers to hexadecimal.
Image to Base64 Converter
Turn an image into a Base64 data URI for CSS, HTML or JSON.
Base64 to Image Converter
Decode a Base64 string back into a viewable, downloadable image.
Image Colour Picker
Pick any colour from an image and get HEX, RGB and HSL.
Text Case Converter
Convert text between sentence, title, upper, lower and code cases.
Remove Duplicate Lines
Strip repeated lines from a list, with a count of what went.
Sort Lines
Sort a list alphabetically, numerically, by length or randomly.
Find and Replace Text
Search and replace across text, with regular expression support.
Add Line Numbers
Number every line of text, with control over format and start.
Text Diff Checker
Compare two texts and highlight exactly what changed.
URL Slug Generator
Turn any title into a clean, SEO-friendly URL slug.
Text to Binary Converter
Convert text into its binary representation, byte by byte.
Binary to Text Converter
Decode binary back into readable text.
Text to ASCII Converter
Convert between text and character codes in any base.
Markdown Previewer
Write Markdown and see the rendered result side by side.
About Developer Tools
The JSON suite is the workhorse: a formatter with configurable indentation, a validator that reports the exact line and column of a syntax error, a minifier for shipping, and converters to and from CSV and YAML.
Encoding and hashing tools use the browser primitives directly — Web Crypto for SHA-1, SHA-256, SHA-384 and SHA-512, TextEncoder for UTF-8 safe Base64 — so results match what your backend produces.
Reference tools such as the HTTP status code lookup, MIME type lookup and cron expression explainer save you a tab and a search. They are static data, so they work instantly and never go down.
Developer Tools FAQs
Is it safe to paste production data into these tools?
These tools never transmit your input — everything is computed in your browser tab. That said, treat any web page as untrusted for live production secrets, and prefer rotating a credential you have pasted anywhere.
Does the JWT decoder verify signatures?
It decodes and displays the header, payload and claim timings, and it checks expiry. It does not verify the signature, because that requires your secret or public key. Verifying signatures should happen on your server.
Why is MD5 offered if it is insecure?
MD5 is still widely used as a non-cryptographic checksum for cache keys, file deduplication and legacy integrations. The tool clearly warns that it must not be used for passwords or signatures.
Do the formatters change my code semantics?
No. The HTML, CSS, JavaScript and SQL formatters only rewrite whitespace and layout. If a formatter cannot parse your input it reports the error instead of guessing.