Developer Tools

Format, encode, minify, and convert data in the browser

23 tools in this category.

Developer tools format and convert data in the browser. The JSON Formatter pretty-prints with two-space indentation, minifies, or validates. It uses the browser’s JSON parser, so comments, trailing commas, and single quotes fail. {"a":1,} is reported as invalid JSON at position 7. JSON and CSV converters run only after the input parses. Base64 encodes text as UTF-8 and is not encryption. Hash tools compute SHA-256, SHA-384, or SHA-512 and cannot reverse a hash. A regular expression is tested against the sample you type.

Use them when you want a result on the page without installing a package. Minifiers and converters follow the rules of each format, so invalid HTML, CSS, JavaScript, or Markdown is rejected instead of silently rewritten. Color tools turn a 3-digit, 6-digit, or 8-digit hex value into RGB and HSL, check contrast, and build a CSS gradient or box shadow. Pasted text stays in the tab. A document over the tool’s size cap is rejected so the page stays usable.

Useful starting points

JSON Formatter

Developer Tools

Pretty-print JSON, minify it, or check that it parses in the page. Comments, trailing commas, and single quotes fail. It does not turn the result into CSV.

Base64 Encoder

Developer Tools

Encode text to Base64 or decode it back, using UTF-8. Anyone can decode the result, so it is not a way to hide a password. A file drop is not accepted.

UUID Generator

Developer Tools

Generate one or many UUID v4 values in your browser using a secure random source.

URL Encoder

Developer Tools

Encode or decode URL components in your browser with encodeURIComponent.

Unix Timestamp Converter

Developer Tools

Convert Unix timestamps to dates and dates back to timestamps, in seconds or milliseconds.

Hex to RGB

Developer Tools

Convert 3-digit, 6-digit and 8-digit hex colors to RGB, RGBA and HSL in your browser.

HTML Encoder / Decoder

Developer Tools

Encode or decode HTML entities in your browser. Input is treated as text, not executed.

HTML Minifier

Developer Tools

Minify HTML in your browser with a conservative pass that keeps pre, textarea, script and style content.

CSS Minifier

Developer Tools

Minify CSS in your browser while preserving strings, URLs, comments and important spacing.

JavaScript Minifier

Developer Tools

Minify JavaScript in your browser with a parser. The code is not executed.

Color Contrast Checker

Developer Tools

Check WCAG contrast between foreground and background colors, with pass/fail for AA and AAA.

CSS Gradient Generator

Developer Tools

Build linear, radial or conic CSS gradients, or gradient text, and copy the CSS or HTML.

Box Shadow Generator

Developer Tools

Tune offset, blur, spread and color, then copy a CSS box-shadow value.

Markdown to HTML

Developer ToolsNew

Convert Markdown to HTML source in your browser. Raw HTML is escaped and not executed.

HTML to Markdown

Developer Tools

Convert HTML source into Markdown in your browser. Input is treated as text and is not executed.

JSON to CSV

Developer Tools

Turn an array of JSON objects into CSV, including commas and quotes inside cells.

CSV to JSON

Developer Tools

Turn CSV with a header row into JSON, including quoted commas and escaped quotes.

Regex Tester

Developer Tools

Test a regular expression against sample text and see each match, its position, and its groups.

Hash Generator

Developer Tools

Create a SHA-256, SHA-384, or SHA-512 digest of text in your browser. This is a hash, not encryption.

Time Zone Converter

Developer Tools

Convert a date and time between two time zones using the browser time-zone list.

JWT Decoder

Developer Tools

Decode a JSON Web Token header and payload in your browser. The signature is not checked.

.gitignore Generator

Developer Tools

Build .gitignore text from Node, Next.js, environment, and other templates, plus your own patterns.

Cron Expression Generator

Developer Tools

Build a five-field cron expression or explain one. Sunday is 0. Month and weekday names are not accepted.

Guide

What Is JSON?

JSON is a text format for objects and arrays. See how to read it, why it fails to parse, and how to format it in the browser.

Guide

How to Convert a Hex Color to RGB

Split a hex color into red, green, and blue pairs and convert each pair from base 16 to a number from 0 to 255.

Guide

How to Percent-Encode a URL Value

Encode a URL component with encodeURIComponent, or decode a percent-encoded string back to text.

Guide

How to Read a Unix Timestamp

Turn seconds or milliseconds since 1970-01-01 UTC into a UTC date, or turn a UTC date back into a timestamp.

Guide

How to Escape HTML So It Shows as Text

Replace <, >, &, and quotes with entities so markup is shown as text, or turn those entities back into characters.

Guide

How to Check Contrast Between Two Colors

Compare two solid colors and read the WCAG 2 ratio, including AA and AAA for normal and large text.

Guide

How to Write a CSS Gradient

Build a linear, radial or conic CSS gradient from at least two color stops and copy the background or gradient text CSS.

Guide

How to Write One CSS Box Shadow

Set one offset, blur, spread, color, and opacity, then copy a single box-shadow declaration.

Guide

How to Turn a JSON Array into CSV

Turn a JSON array of objects into CSV. The first row is the keys, and commas inside cells are quoted.

Guide

How to Turn CSV into JSON

Use the first CSV row as keys and turn each following row into a JSON object.

Guide

How to Test a Regular Expression

Run a JavaScript regular expression on sample text and read each match, its index, and its capture groups.

Guide

How to Hash Text with SHA-256, SHA-384, or SHA-512

Hash pasted text with SHA-256, SHA-384, or SHA-512. The hex is a fingerprint, not a way back to the text.

Guide

How to Read a Cron Expression

Read a five-field cron expression. When both day fields are set, cron matches either day, not both.

Guide

How to Write a .gitignore File

Build .gitignore text from Node, Next.js, environment, and other templates. Generating the text does not update a repository.

Guide

What Base64 Is, and How to Encode Text

Encode text to Base64 after UTF-8, or decode it back. The result is not encryption.

Guide

What a UUID Is, and How to Generate One

Generate 1 to 100 random UUID version 4 values. They are not sequential keys or passwords.

Guide

How to Read a JWT Without Treating It as Verified

How to read a JWT header and payload, and why that does not verify the signature.

Guide

How to Convert a Time Between Zones

How to convert the same instant between two time zones, without turning it into a Unix timestamp.

Calculators

27 tools

Everyday calculation tools

Text Tools

15 tools

Tools for writing and text processing

Image Tools

18 tools

Browser-based image and PDF tools

SEO & Utilities

12 tools

Links, slugs, QR codes, and passwords

AI Tools

6 tools

Prompt builders and writing tools, with optional Gemini AI