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183 free developer tools.
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No data leaves your machine — every tool runs entirely in your browser. Format JSON, convert images, merge PDFs, generate UUIDs, and audit any site's SEO. 183 free, focused, no-signup tools in one place.
0–100 score + prioritized fixes · no signup · free
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183 tools, one tab
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Popular tools
JSON Prettify / Minify
Format, validate, and minify JSON
SEO Analyzer
Full SEO audit: paste one URL for a 0–100 score and prioritized fixes across meta, content, links, images, structured data, social, and security headers
Base64 Encode / Decode
Encode and decode Base64 text and files
Merge PDFs
Combine multiple PDF files into one
UUID Generator
Generate v4 UUIDs in bulk with one-click copy
Image Compressor
Compress images with adjustable quality
All tools
CSV ↔ JSON
Convert between CSV and JSON formats
YAML ↔ JSON
Bidirectional conversion between YAML and JSON
TOML ↔ JSON
Bidirectional conversion between TOML and JSON
XML ↔ JSON
Bidirectional conversion between XML and JSON
JSON → TypeScript Types
Generate TypeScript interfaces from JSON samples
JSON → Zod Schema
Generate Zod validation schemas from JSON samples
JSON → Go Struct
Generate Go structs with json tags from JSON
JSON → Rust (Serde)
Generate Rust serde structs from JSON
JSON → Kotlin Data Class
Generate Kotlin data classes from JSON
JSON → C# Class
Generate C# classes with System.Text.Json attributes from JSON
JSON → Java Class
Generate Java classes with Jackson annotations from JSON
JSON → GraphQL Schema
Generate GraphQL SDL types from JSON
JSON Diff
Compare two JSON objects structurally
JSON → JSDoc Typedefs
Generate JSDoc @typedef definitions from JSON
CSV → SQL INSERT
Convert CSV rows into SQL INSERT statements
SQL Explainer
Explain any SQL query in plain English, clause by clause
JSON ↔ Query String
Convert between URL query params and JSON objects
JSON → CSV
Convert a JSON array of objects into CSV
JSON Schema Generator
Generate JSON Schema from sample JSON data
ULID Generator
Generate sortable unique identifiers (ULID)
UUID Generator
Generate v4 UUIDs in bulk with one-click copy
BIP39 Mnemonic Generator
Generate and validate BIP39 mnemonic seed phrases
Barcode Generator
Generate 1D barcodes (Code128, EAN, UPC, and more)
Hash Generator
Generate MD5, SHA-1, SHA-256, SHA-512 hashes
HMAC Generator
Generate HMAC digests with a secret key
RSA / EC Key-Pair Generator
Generate RSA or EC key pairs as PEM
Placeholder Image Generator
Generate colored placeholder images at custom dimensions
QR Code Generator
Generate QR codes from text or URLs
WiFi QR Code Generator
Generate a QR code to join a WiFi network
Password Generator
Generate secure random passwords with crypto API
Lorem Ipsum Generator
Generate placeholder text in paragraphs, sentences, or words
Favicon Generator
Upload an image and generate favicons with custom shape, border, and padding
Crontab Builder
Build cron expressions visually with dropdowns and presets
Password Strength Analyzer
Check password entropy, strength, and crack time
Fake Data Generator
Generate realistic fake/mock test data and export to JSON, CSV, or SQL
Sample File Generator
Generate real, valid sample/dummy files at an exact size
API Key Generator
Generate secure API keys and secrets in various formats
bcrypt Hash & Verify
Generate and verify bcrypt password hashes
.htpasswd Generator
Generate Apache .htpasswd entries with bcrypt or SHA
TOTP Generator & Validator
Generate and validate time-based one-time passcodes
NATO Phonetic Alphabet
Spell text using the NATO phonetic alphabet
Emoji Picker
Search emoji by name and copy with one click
ASCII Art Generator
Turn text into FIGlet-style ASCII art
Case Converter
Convert text between camelCase, snake_case, kebab-case, and more
Text Diff
Compare two texts and see highlighted differences
Regex Tester
Test regular expressions with highlighted matches
Word / Character Counter
Live count of characters, words, sentences, and reading time
Find & Replace
Find and replace text with regex support
String Escape / Unescape
Escape and unescape strings for JSON, HTML, URL, and more
Unicode Inspector
Inspect code points and UTF-8 bytes of any text
Line Sort / Deduplicate
Sort lines alphabetically or numerically, remove duplicates
Text to Slug
Convert any text to a URL-friendly slug
Fancy Text Generator
Turn text into fancy Unicode styles — bold, italic, cursive, and more
Upside-Down Text
Flip your text upside down
Mirror & Reverse Text
Reverse text backwards or mirror it with flipped letters
Zalgo / Glitch Text
Generate glitchy, cursed Zalgo text
Aesthetic Text Generator
Make fullwidth and spaced-out aesthetic / vaporwave text
Text Repeater
Repeat any text N times with optional separators
Invisible Character
Copy invisible Unicode characters for blank messages and names
Regex Library
Curated library of common regex patterns with one-click copy
ASCII Table
Searchable ASCII character code reference
JSON Path Finder
Paste JSON and explore all paths to values
Chmod Calculator
Visual permission calculator for Unix
.gitignore Generator
Select presets and generate a combined .gitignore
Environment Variable Parser
Parse .env files and convert between formats
Tailwind → CSS Converter
Paste Tailwind classes and see equivalent CSS
Aspect Ratio Calculator
Calculate dimensions from aspect ratios
Bytes / Filesize Converter
Convert between B, KB, MB, GB, TB
Package.json Explorer
Paste package.json to see a clean breakdown of dependencies and scripts
SSH Key Generator
Generate RSA SSH key pairs in your browser
robots.txt Generator
Build robots.txt files with user-agent rules and presets
Docker Run → Compose
Convert a docker run command to docker-compose.yaml
Dependency Vulnerability Scanner
Scan npm lockfiles for known vulnerabilities (CVEs) via the OSV database
.htaccess Generator
Build .htaccess files with redirects, security, caching, and more
Email Normalizer
Normalize emails and find duplicates
.editorconfig Generator
Generate an .editorconfig file from a form
Markdown TOC Generator
Generate a table of contents from Markdown headings
JSON Prettify / Minify
Format, validate, and minify JSON
SQL Formatter
Prettify SQL queries
HTML Prettify / Minify
Format or compress HTML
CSS Prettify / Minify
Format or compress CSS
JavaScript Prettify / Minify
Format or compress JavaScript
XML Prettify / Minify
Format or compress XML
Markdown Preview
Live side-by-side Markdown editor and rendered preview
HTML Preview
Paste raw HTML and see it rendered in a sandboxed iframe
Markdown Table Generator
Build GitHub-flavored Markdown tables in a visual grid
Markdown → HTML Converter
Convert Markdown to clean HTML with live preview
Markdown → PDF Converter
Convert Markdown to a styled PDF document with customizable options
HTML → Markdown
Convert HTML into clean, readable Markdown
Random Port Generator
Generate random TCP/UDP port numbers
IPv4 Subnet Calculator
Calculate network, broadcast, host range, and mask from CIDR
IP Range / CIDR Expander
Expand a CIDR block or IP range into every address
IPv6 Expander / Compressor
Expand or compress IPv6 addresses
MAC Address Generator
Generate random MAC addresses in any format
Well-Known Port Reference
Search common TCP and UDP port numbers
User-Agent Parser
Parse a User-Agent into browser, OS, and device
What Is My IP
See your public IP address, location, and connection details
DNS Lookup
Look up DNS records for any domain (A, MX, TXT, NS, and more)
Base64 Encode / Decode
Encode and decode Base64 text and files
URL Encode / Decode
Encode and decode URI components
JWT Decoder
Decode JWT tokens and inspect header, payload, and expiration
AES Encrypt / Decrypt
Encrypt and decrypt text with AES-256-GCM and a password
X.509 Certificate Decoder
Decode and inspect X.509 PEM certificates
Number Base Converter
Convert between decimal, hex, binary, and octal
Text ↔ Binary
Convert text to binary and back
Text ↔ Hex
Convert text to hexadecimal and back
Base32 Encode / Decode
Encode and decode Base32 (RFC 4648)
Base58 Encode / Decode
Encode and decode Base58 (Bitcoin alphabet)
Roman Numeral Converter
Convert numbers to Roman numerals and back
HTML Entity Encoder / Decoder
Encode and decode HTML entities with named and numeric support
JWT Generator
Generate and sign JWT tokens with HMAC algorithms
Image Compressor
Compress images with adjustable quality
Image Format Converter
Convert images between PNG, JPEG, and WebP
Font Converter
Convert fonts between TTF, OTF, WOFF, and WOFF2
Image Resizer
Resize images with aspect ratio lock
SVG to PNG
Convert SVG to PNG at 1x, 2x, or 3x scale
SVG Optimizer
Optimize and minify SVG files
Base64 ↔ Image
Convert images to base64 data URLs and vice versa
Image Metadata Viewer
View dimensions, file size, and EXIF data
Image Color Picker
Upload an image and click to pick colors
Bulk Image Processor
Compress, resize, and convert multiple images at once
Image Pipeline
Chain resize, format, and compress operations on a single image
PNG → ICO
Convert an image into a multi-resolution .ico favicon
Image Color Palette
Upload an image and extract its dominant colors
Code to Image
Turn code snippets into beautiful images with gradient backgrounds
SVG → React Component
Convert SVG markup into React/JSX components
App Store Screenshots
Generate marketing-style App Store screenshots with device frames
Merge PDFs
Combine multiple PDF files into one
Split PDF
Split a PDF into multiple files
Rotate PDF Pages
Rotate pages in a PDF
Sign PDF
Add a signature to a PDF
Reorder PDF Pages
Rearrange pages in a PDF by dragging and dropping
Remove PDF Pages
Delete specific pages from a PDF
Extract PDF Pages
Extract specific pages from a PDF into a new file
Images to PDF
Convert images to a multi-page PDF document
PDF to Images
Convert PDF pages to PNG or JPEG images
Add Page Numbers to PDF
Add page numbers to every page of a PDF
PDF Metadata Editor
View and edit PDF metadata like title, author, and keywords
PDF Pipeline
Chain multiple PDF operations: remove, rotate, add page numbers
PDF Compressor
Reduce PDF file size in your browser — lossless or strong compression
Color Converter
Convert between hex, RGB, HSL, and OKLCH
Color Palette Generator
Generate harmonious color palettes from a base color
Contrast Checker
Check WCAG AA/AAA contrast ratios
Gradient Generator
Visual gradient builder with CSS output
Theme Editor
Generate custom shadcn/ui themes with OKLCH color variables
Color Blindness Simulator
Simulate how images and colors look with different types of color blindness
Box-Shadow Generator
Build CSS box-shadows visually with layered shadows
cubic-bezier() Editor
Drag a curve to build a CSS easing function
CSS clamp() Calculator
Generate fluid clamp() font sizes
Border-Radius Generator
Round corners visually and copy the CSS
Flexbox & Grid Playground
Build Flexbox and CSS Grid layouts visually
Squircle Generator
Generate iOS-style squircle (superellipse) shapes
Glassmorphism & Neumorphism
Generate glassmorphism and neumorphism CSS
Timestamp Converter
Convert between Unix timestamps and human-readable dates
URL Parser
Break a URL into its components
HTTP Status Code Reference
Searchable list of HTTP status codes
Meta Tag Generator
Generate HTML meta tags, Open Graph, and Twitter Card tags
Cron Expression Parser
Parse cron expressions into human-readable descriptions
Epoch Batch Converter
Convert a list of Unix timestamps to human-readable dates
Timezone Converter
Convert a date and time between time zones
Duration Calculator
Time and business days between two dates
Date Format Converter
Convert a date between ISO, Unix, RFC, and more
Countdown Timer
Live countdown to any future date
OG / Social Card Preview
Preview Open Graph and Twitter Card meta tags with live social previews
CSP Header Builder
Build Content Security Policy headers with a visual form
Webhook Tester
Send test POST requests to webhook endpoints and inspect responses
HTTP Request Builder
Send HTTP requests and inspect responses — a lightweight online API client
SEO Analyzer
Full SEO audit: paste one URL for a 0–100 score and prioritized fixes across meta, content, links, images, structured data, social, and security headers
Meta Tag Analyzer
Analyze any webpage's meta tags, Open Graph, and Twitter Card data
Heading Structure Checker
Check any page's heading hierarchy for SEO issues
Link Analyzer
Analyze all internal and external links on any webpage
Image SEO Checker
Check images on any webpage for missing alt text and SEO issues
Structured Data Validator
Validate JSON-LD structured data on any webpage
Technology Detector
Detect what technologies any website is built with
Redirect Checker
Follow the full redirect chain for any URL
SEO Report
Run a full SEO analysis on any URL — meta tags, headings, links, images, and structured data, all on one page
HTTP Header Analyzer
Analyze HTTP response headers and grade security headers
Schema Markup Generator
Generate JSON-LD structured data for any schema.org type
Keyword Density Analyzer
Analyze keyword and phrase frequency in any text
Sitemap Generator
Generate a valid XML sitemap from a list of URLs