Free online developer and conversion tools

Free browser-based tools for JSON, YAML, CSV, Base64, images, text, code, security, and developer workflows. Fast, practical, and no signup required.

Format & Code Conversion

JSON, YAML, XML & CSV Converter — Convert between JSON, YAML, XML, and CSV formats
JSON to Code Models — Convert JSON to C#, TypeScript, Java, Python, Go, Kotlin, and more
Number Base Converter — Convert between Decimal, Binary, Octal, and Hexadecimal
cURL to Code Converter — Convert cURL commands to JavaScript, Python, Go, PHP, Java, C#, and Rust code
SVG to React & JSX Converter — Convert raw SVG markup into clean React, Vue, Svelte, and TSX components
JSON to TypeScript & Zod Converter — Generate TypeScript interfaces and Zod validation schemas from JSON payload
CSS to Tailwind CSS Converter — Convert traditional CSS properties into utility Tailwind CSS classes

Encoding & Decoding

Base64 Encoder & Decoder — Encode and decode Base64 data
URL Encoder & Decoder — Encode and decode URLs
Text & Hex Converter — Convert text to Hex and vice versa
Text & Binary Converter — Convert text to Binary and vice versa

Generators

UUID Generator — Generate UUIDs (v1, v4)
Hash Generator — Generate MD5, SHA-1, SHA-256 hashes
Lorem Ipsum Generator — Generate Lorem Ipsum placeholder text
QR Code Generator — Generate QR Codes
Placeholder Text — Generate Lorem, Bacon, Hipster, and Corporate Ipsum
Mock Data Generator — Generate mock data (JSON, CSV, SQL) based on schema
Favicon Generator — Generate favicons and ICO files from images

Text & Content

Text Case & Cleanup — Change case, remove duplicates, and more
Slug Generator — Generate URL-friendly slugs
Text Encryption & Decryption — Encrypt and decrypt text (AES, DES, etc.)
Markdown Editor — Markdown editor with live preview and HTML export
ASCII Art Generator — Generate ASCII art from text
Diff Checker — Compare and find differences between two texts
Word Counter — Count words, characters, sentences, and paragraphs
HTML Entity Encoder & Decoder — Encode and decode HTML entities
String Escape & Unescape — Escape and unescape strings for various formats
Regex Tester — Test regular expressions with live matching
Markdown Table Builder & Converter — Interactive visual Markdown table generator and CSV/HTML to Markdown converter
Unicode Fancy Font Generator — Convert text to Unicode aesthetic styles for Instagram bios, TikTok, and Twitter
Instagram & TikTok Caption Line Breaker — Format social media captions with invisible clean line breaks
Twitter / X Thread Splitter — Automatically split long articles or posts into numbered 280-character tweet threads

Images & Files

Image Converter — Convert images between formats (PNG, JPG, WEBP)
Resize, Rotate & Compress Images — Batch resize, compress, convert, rotate, and flip images
Image Merger — Merge multiple images in split layouts (2 or 4 images)
SVG Optimizer — Optimize and minify SVG files
Image Quality Enhancer & Upscaler — Upscale resolution (up to 4x), sharpen blurry edges, and enhance contrast in real-time
Image & PDF Scan Effect Generator — Make JPG, PNG images and PDF documents look like scanned copies with adjustable effects
Social Media Aspect Ratio Calculator — Calculate pixel dimensions and aspect ratios for YouTube, TikTok, and Instagram
PDF Tools & Page Manager — 100% private client-side PDF tools: Merge multiple PDFs, split & extract custom page ranges, rotate pages, and convert PNG/JPG images to PDF

Date & Time

Unix Timestamp Converter — Convert Unix seconds or milliseconds to readable dates and back
Time Zone Converter — Convert local times between world time zones with daylight-saving support
Date Difference & Calculator — Count days between dates or add and subtract days, weeks, months, and years
Time Unit & Tick Converter — Convert duration units and .NET ticks to dates or Unix timestamps
World Timezone & Meeting Planner — Plan meetings across global time zones by comparing working hour overlaps

Color & Design

Color Converter — Convert colors (Hex, RGB, HSL)
Color Palette & Contrast — Generate color palettes and check contrast
WCAG Color Contrast Checker — Calculate color contrast ratio and verify WCAG AA/AAA accessibility compliance

Code & Developer Tools

Git Helpers — .gitignore generator, commit validator, URL parser
JSON Beautifier & Validator — Format, validate, safely repair, minify, and sort JSON locally in your browser
Code Formatter — Format and minify JavaScript, HTML, and CSS
Regex Pattern Library — Common regex patterns and tester
HTML Viewer & Playground — Build and preview HTML, CSS, and JavaScript, then export a single file or project ZIP
Cron Parser & Execution Scheduler — Parse CRON expressions into human language and calculate upcoming execution schedules
Docker Run to Docker Compose Converter — Convert CLI docker run commands to clean docker-compose.yml files
Git Interactive Command Generator — Interactive builder for complex Git workflow commands and undo actions
Regex Pattern Visualizer — Visual breakdown and structural diagram for Regular Expressions
OpenAPI & Swagger to Postman Collection Generator — Convert OpenAPI 3.0/3.1 and Swagger JSON/YAML into Postman Collections and Environment files with folder grouping by tags

Data & SQL

JSON Schema Generator & Validator — Infer JSON Schema from JSON payload and validate JSON against schema specifications
SQL Formatter — Format and validate SQL queries
CSV Toolkit — CSV to JSON, Transpose, and more
CSV to SQL Generator — Convert CSV data to SQL schema with intelligent type inference and multiple database dialects

API & Network

API Test Builder — Create, organize, send, import, and export reusable browser-based API request collections
Temporary Mock API — Create a short-lived JSON endpoint for testing API clients and integrations
HTTP Request Tester — Send HTTP requests and view responses
WebSocket Tester — Test WebSocket connections
DNS Lookup — Perform DNS lookups and troubleshooting
What Is My IP & Network Info — Find your public IPv4, IPv6, ISP, location, timezone, and WebRTC leak status
Internet Speed & Latency Test — Test your download speed, upload speed, ping latency, and jitter in real-time
OpenGraph & Social Card Previewer — Generate OpenGraph meta tags and preview Twitter, Facebook, LinkedIn & Discord cards
Subnet & CIDR IP Calculator — Calculate IP subnet mask, broadcast address, CIDR range, and usable host count
User-Agent String Parser — Parse User-Agent headers to detect browser, OS, engine, CPU, and device specs
OpenGraph & Social Image Extractor — Extract OpenGraph thumbnail images, titles, and social metadata from website URLs
Internet Stability, Jitter & Bufferbloat Test — Measure latency jitter, packet loss rate, and bufferbloat lag under load for gaming, Zoom, and streaming
Live HTTP Headers & Redirect Chain Inspector — Trace multi-hop 301/302 redirects, examine HTTP response headers, and audit HSTS & CSP security policies

Security & Tokens

JWT Decoder, Generator & Verifier — Decode, verify, and generate JWTs
Password Generator — Generate secure passwords with customizable options
SSL & OpenSSL Setup Guide — Generate Certbot commands, Let’s Encrypt configs, and OpenSSL self-signed certificate commands
File Encryption & Decryption — Encrypt and decrypt any file locally with a passphrase using AES-256-GCM
Chmod Calculator — Calculate Linux/Unix file permissions with octal numbers and symbolic notation
Bcrypt Hash Generator & Verifier — Generate secure Bcrypt password hashes and verify hashes against plain text
Ed25519 & RSA SSH Key Generator — Browser-side OpenSSH key pair generator using WebCrypto API
HTPASSWD Basic Auth Generator — Generate Nginx and Apache .htpasswd entries with bcrypt or MD5 hashing

AI & Prompt Tools

LLM Token Counter & Price Estimator — Calculate token counts and API costs for GPT-4o, Claude 3.5 Sonnet, Gemini 1.5, and Llama 3
Codebase to Prompt Packager — Package multiple code files into a clean LLM-friendly XML structure for ChatGPT & Claude
AI System Prompt & Persona Builder — Visual builder for structured AI System Prompts (Role, Constraints, Output Specs, Rules)
Midjourney & Stable Diffusion Prompt Builder — Visual builder for AI image generation prompts with styles, lighting, aspect ratios, and parameters
OpenAI & Claude Function / Tool Spec Builder — Convert JSON payloads and schemas into OpenAI Function Calling & Claude Tool Spec JSON
LLM Response Cleaner & Code Extractor — Strip conversational fluff from ChatGPT/Claude responses and extract pure code blocks
AI Prompt Enhancer & Quality Optimizer — Transform basic text prompts into structured, high-quality prompts using proven frameworks
Site AI Compatibility & GEO Scanner — Audit AI bot permissions, validate llms.txt, check Schema.org JSON-LD, and optimize for ChatGPT Search & Perplexity

Games & Retro Tools

Image to Pixel Art & Retro Palette Studio — Convert images to 8-bit & 16-bit retro pixel art with Game Boy, NES, and PICO-8 palettes, dithering, and SVG/CSS export
Retro Snake Arcade Game — Play the classic 8-bit retro Snake game with Game Boy & Neon themes, Web Audio chiptune sound effects, and high scores
2048 Number Puzzle Game — Slide matching number tiles to reach 2048 with smooth animations, undo moves, customizable board sizes, and swipe controls
Retro Minesweeper Classic — Classic Windows-style Minesweeper with safe first-click guarantee, timer, flags, digital counter, and sound effects
Retro Klondike Solitaire — Classic Klondike Solitaire card game with Turn 1 & Turn 3 modes, intelligent hints, auto-complete, customizable themes, and victory animation
Retro River Naval Defense — Classic retro river tower defense game: Place coastal cannons, ballistas, and howitzers along the winding river to sink enemy warship fleets
Classic Sudoku & Solver — Play classic 9x9 Sudoku puzzles with 4 difficulty levels, pencil notes, error checking, and an instant backtracking solver for external puzzles
Retro Falling Blocks Arcade — Classic 8-bit retro falling tetromino blocks puzzle game: clear lines, score combos, hold queue, ghost piece projection, and chiptune sound effects

Hardware & Device Tests

Dead Pixel & Monitor Test — Full-screen solid colors, gradients, and checkerboard patterns to spot dead pixels, stuck pixels, and backlight bleed
Keyboard Tester — Press any key to see it highlight on a full on-screen keyboard, log key codes, and test for stuck keys or rollover issues
Mouse Tester — Test left, right, and middle click, double-click misfires, scroll wheel, and mouse movement in real-time
Touchscreen Test — Multi-touch point map for phones, tablets, and touchscreen laptops to find dead zones and check touch accuracy
Gamepad Tester — Connect a controller and see every button press, trigger, and analog stick movement live, with stick drift detection
Speaker & Audio Channel Test — Play tones through left and right channels and sweep frequencies to test speakers, headphones, and audio balance
Microphone Test — Check your microphone input level in real-time with a live volume meter, entirely in your browser with no recording or upload
Webcam Test — Preview your webcam locally in the browser and check resolution and frame rate, with no video ever leaving your device
Screen Refresh Rate Test — Measures the actual refresh rate of your monitor in real-time and shows a moving bar to visually check for judder
Device Sensor Test — Live readout of your phone or tablet accelerometer, gyroscope, and compass sensors, entirely in your browser
Battery Status — Shows the current battery charge level, charging state, and estimated time remaining for this device where the browser supports it
CPU Benchmark — Scores single-core and multi-core CPU throughput with a real Web Worker workload, entirely in your browser
Memory Info & Benchmark — Shows what the browser exposes about system memory and measures real allocation throughput, entirely in your browser
GPU Benchmark — Renders an animated WebGL stress test and measures sustained frame rate as a relative GPU throughput score
Storage Speed Test — Measures real read and write throughput to the browser sandboxed storage and shows storage quota usage

Focused conversion guides

JSON to YAML Converter — Convert JSON to readable YAML online with a fast browser-based converter. Validate the input, preserve nested data, and copy the YAML output.
YAML to JSON Converter — Convert YAML to valid JSON online. Check indentation errors, preserve nested structures, and copy formatted JSON in your browser.
JSON to CSV Converter — Convert arrays of JSON objects to CSV online. Generate spreadsheet-ready rows with consistent headers and downloadable output.
CSV to JSON Converter — Convert CSV rows to structured JSON online. Parse headers, quoted values, and tabular data directly in your browser.
CSV to SQL Converter — Convert CSV data to CREATE TABLE and INSERT statements online with type inference and support for multiple SQL dialects.
Base64 Encoder — Encode UTF-8 text as Base64 online. Generate a copy-ready Base64 value locally in your browser without signup.
Base64 Decoder — Decode Base64 to readable UTF-8 text online. Validate and inspect encoded values locally in your browser.
Unix Timestamp to Date Converter — Convert Unix timestamps in seconds or milliseconds to UTC, ISO 8601, and local dates. Choose the input unit explicitly when automatic detection is ambiguous.
Timestamp to Date Converter — Convert timestamps to human-readable dates online. Real-time UTC, ISO 8601, and local time conversion for developers and system administrators.
Epoch to Date Converter — Convert Epoch seconds and milliseconds to readable date formats online. Free, instant, and accurate epoch time converter for developers.
Merge Images Online — Merge two photos side by side or vertically, or combine four images in a 2x2 grid. Preserve or normalize sizes and download PNG, JPEG, or WebP.
HTML Online Viewer & Live Preview — View and test HTML, CSS, and JavaScript code online with instant real-time live preview. Secure sandboxed iframe preview with export capabilities.
URL Encode & Decode Online — Encode and decode URLs and query parameters online. Fast, RFC 3986 compliant URL encoder and decoder with UTF-8 support.
Binary to Text & Text to Binary Converter — Convert binary code (0s and 1s) to ASCII text and plain text to binary online. Instant browser-based conversion with customizable byte spacing.
PNG to WebP Converter — Convert PNG images to WebP online in your browser and download a web-ready image while preserving transparent pixels when supported.
HEX to RGB Color Converter — Convert HEX color codes to RGB values online with instant validation, visual preview, and CSS code copy.
Make a PDF Look Scanned — Make a digital PDF look scanned in your browser using paper tone, noise, and scan presets. Process up to 50 pages per PDF and download image-based PDF output.
Make a Picture Look Scanned — Turn a JPG or PNG photo into a realistic scanned document online. Free scan effect with paper texture, noise, fax and aged presets - processed privately in your browser.
Encrypt & Decrypt Text Online — Encrypt or decrypt sample text using AES or legacy CryptoJS ciphers. Match key size, mode, and encoding; processing is local and inputs are saved in this browser.