Developer Tools

Free Online Tools

Handy utilities for your everyday development workflow. No sign-up required — just open and use.

Formatters

Format, validate, and beautify JSON with syntax highlighting

Compare two texts and see differences highlighted side by side

Markdown Previewer

Write Markdown and preview the rendered output in real time

Encoders & Decoders

Base64 Encoder/Decoder

Encode and decode text or files to and from Base64

URL Encoder/Decoder

Encode and decode URLs and query string parameters

HTML Entity Encoder/Decoder

Convert special characters to and from HTML entities

Generators

Generate random UUIDs in bulk with one-click copy

Lorem Ipsum Generator

Generate placeholder text by words, sentences, or paragraphs

Generate SHA-1, SHA-256, and SHA-512 hashes from text

QR Code Generator

Generate downloadable QR codes from text or URLs

Converters

Color Converter

Convert colors between HEX, RGB, and HSL formats

Timestamp Converter

Convert between Unix timestamps, ISO 8601, and human-readable dates

CSS Unit Converter

Convert between px, rem, em, vh, and vw units

Cron Expression Parser

Parse cron expressions and see the next scheduled run times

Inspectors

Write and test regular expressions with real-time match highlighting

Decode and inspect JSON Web Tokens — header, payload, and expiry

Text & Code

JSON to TypeScript

Paste JSON and get TypeScript interfaces generated automatically

Format and beautify SQL queries with proper indentation

Minify HTML, CSS, and JavaScript code to reduce file size

String Case Converter

Convert text between camelCase, snake_case, PascalCase, kebab-case, and more

Count characters, words, sentences, paragraphs, and reading time

Visualize whitespace, convert line endings, and escape/unescape text

Character Picker

Search Unicode characters and emojis by name and copy them

Bulk find and replace in text with regex support and live preview

HTML to JSX Converter

Convert HTML to JSX — class to className, for to htmlFor, style objects, and self-closing tags

Tailwind to CSS Converter

Convert Tailwind CSS utility classes to plain CSS properties

Code Screenshot Generator

Generate beautiful code screenshots with custom themes, fonts, and backgrounds

Networking & API

cURL to Code Converter

Convert cURL commands to JavaScript fetch, Python requests, and Node.js axios code

HTTP Status Codes

Searchable reference of all HTTP status codes with descriptions

Query String Parser

Parse URLs into components and query parameters, or build URLs from params

CORS Header Builder

Configure CORS headers and get config snippets for Express, Next.js, and nginx

DNS Record Reference

Searchable reference of all DNS record types with descriptions and examples

Security & Crypto

Password Generator

Generate strong passwords with configurable length and character sets

Generate time-based one-time passwords from a secret key

RSA Key Pair Generator

Generate RSA public/private key pairs using Web Crypto API

ROT13/Caesar Cipher

Encrypt and decrypt text with ROT13 and configurable Caesar cipher shifts

Data & Conversion

Convert JSON arrays to CSV format and vice versa

Number Base Converter

Convert numbers between binary, octal, decimal, and hexadecimal

Byte Unit Converter

Convert between KB, MB, GB, TB, KiB, MiB, GiB, and more

Format Converter

Convert between YAML, TOML, JSON, and XML data formats

SEO

Open Graph Preview

Preview how your page looks when shared on Twitter, Facebook, and LinkedIn

Meta Tag Generator

Generate HTML meta tags for SEO, social sharing, and browser behavior

Robots.txt Generator

Build robots.txt files with a visual rule editor

XML Sitemap Generator

Create valid XML sitemaps from a list of URLs

JSON-LD Generator

Build structured data markup for Google rich results (Article, FAQ, HowTo, etc.)

CSS & Design

CSS Gradient Generator

Visual gradient builder with live preview and CSS output

Flexbox Playground

Interactive flexbox property configurator with live preview

CSS Grid Generator

Visual CSS Grid layout builder with code output

CSS Effect Generator

Generate box shadows, border radius, and glassmorphism effects

Screen Calculator

Calculate aspect ratios, PPI, and physical screen dimensions

Responsive Breakpoint Calculator

Calculate responsive breakpoints and generate media queries for popular frameworks

Font & Spacing Scale Generator

Generate typographic and spacing scales from a base size and ratio

Favicon Generator

Upload an image and generate multi-size favicons (16px to 512px) as downloadable PNGs

Dev Productivity

Chmod Calculator

Visual file permission calculator with numeric and symbolic notation

JavaScript Keycode Finder

Press any key to see its keyCode, key, code, and which values

User Agent Parser

Parse user agent strings into browser, OS, and device details

.gitignore Generator

Generate .gitignore files by selecting languages and frameworks

License Generator

Browse and generate open source license files (MIT, Apache, GPL, etc.)

Docker Run to Compose

Convert docker run commands to docker-compose.yml format

Server Config Generator

Generate .htaccess and nginx config snippets for common rules

SSH Config Generator

Visual builder for ~/.ssh/config host entries

Environment Variable Validator

Validate .env files for missing values, duplicates, and formatting issues

NPM Package Comparator

Compare package.json files to find dependency differences and version mismatches

API Response Mocker

Define mock API responses and generate handler code for Express, Next.js, and Hono

Math & Network

IP Subnet Calculator

Calculate network address, broadcast, host range, and CIDR notation

Percentage Calculator

Calculate percentages, increases, decreases, and ratios