All tools
free web developer tools
Converters
Cron Expression Parser
Parse Cron expression to get scheduled dates
Cron Expression Generator
Build cron expressions visually with a cron builder and preview scheduled dates
Date Converter
Convert date to human-readable date and vice versa
JSON Array to Table
Convert a JSON array to tabular format, export to CSV or TSV
JSON <> YAML Converter
Convert JSON data to YAML and vice versa
Number Base Converter
Convert numbers from one base to another
Roman Numeral Converter
Convert between Roman numerals and Arabic numbers
XML <> JSON Converter
Convert XML data to JSON and vice versa
Markdown <> HTML Converter
Convert Markdown to HTML and vice versa
HTML to JSX Converter
Convert HTML markup to JSX syntax for React
JSON <> TOML Converter
Convert JSON data to TOML and vice versa
YAML <> TOML Converter
Convert YAML data to TOML and vice versa
OPML RSS URL Extractor
Extract RSS feed URLs from OPML files
RSS URLs to OPML Generator
Generate OPML files from RSS feed URLs
Data Size / Byte Converter
Convert between different data size units: bits, bytes, kilobytes, megabytes, gigabytes, terabytes, petabytes
cURL to Code Converter
Convert cURL commands to code in multiple languages
JSON to Code Generator
Generate types and classes from JSON for multiple languages
chmod Calculator
Calculate Unix file permissions with visual checkboxes, octal, and symbolic notation
Unit Converter
Convert between units of length, weight, temperature, data size, time, and more
Docker Run to Compose
Convert docker run commands to docker-compose.yml files instantly
Protobuf Decoder / Encoder
Decode Protocol Buffer messages from Base64 or hex without a schema definition
Network
IPv4 Subnet Calculator
Calculate subnet masks, network ranges, and broadcast addresses from CIDR.
IPv4 Address Converter
Convert IPv4 addresses between decimal, hex, and binary formats.
IPv4 Range Expander
Expand IPv4 ranges into address lists and counts.
IPv6 Parser / Expander
Parse, compress, and expand IPv6 addresses.
TLS Version Checker
Check TLS/SSL version, certificate details, and cipher suite for any hostname
Encoders / Decoders
Base64 Image Encoder / Decoder
Encode and decode Base64 image data
Base64 Text Encoder / Decoder
Encode and decode Base64 text data
Certificate Decoder
Decode a certificate
GZip Compress / Decompress
Compress or decompress a text in GZip
HTML Text Encoder / Decoder
Encode and decode HTML text data
JWT Encoder / Decoder
Encode and decode Json Web Token
URL Encoder / Decoder
Encode or decode all the applicable characters to their corresponding URL entities
Quoted-Printable Encoder / Decoder
Encode or decode text using quoted-printable format (RFC 2045)
Hex to ASCII / ASCII to Hex Converter
Convert between hexadecimal and ASCII text formats
Base58 Encoder / Decoder
Encode and decode text using Base58 encoding (used in Bitcoin, IPFS)
GZip Processor
High-performance GZip compression with advanced levels
Base32 Encoder / Decoder
Encode and decode Base32 strings used in TOTP secrets and RFC 4648 applications
Formatters
JSON Formatter
Format, beautify, and minify JSON data instantly. Validate JSON syntax, pretty print with proper indentation, or compress JSON for efficient storage and transmission.
SQL Formatter
Format SQL data
XML Formatter
Indent or minify XML data
CSS Formatter
Format and beautify CSS code
JavaScript Formatter
Format and beautify JavaScript code
HTML Formatter
Format and beautify HTML code
TOML Formatter
Format and beautify TOML configuration files
YAML Formatter
Format and beautify YAML configuration files
Python Formatter
Format and beautify Python code with proper indentation and whitespace normalization
SCSS Formatter
Format and beautify SCSS/Sass code with proper indentation and nesting using Prettier
Generators
Hash / Checksum Generator
Calculate hash values and checksums from text or binary data using MD5, SHA1, SHA256, SHA512, and more. Verify file integrity and generate secure hash codes instantly.
HMAC Generator
Generate HMAC signatures for API authentication, webhooks, and message integrity using SHA-1, SHA-256, SHA-384, or SHA-512.
Bcrypt Generator / Validator
Generate and verify bcrypt password hashes with configurable cost factor
Lorem Ipsum Generator
Generate Lorem Ipsum (or similar) placeholder text
Fake Data / Faker Generator
Generate fake data with quick templates (User, Employee, Product, Order). Export as JSON, YAML, CSV, or SQL.
Password Generator
Generate random passwords
UUID Generator & Decoder
Generate and decode UUIDs version 1, 4 (GUID), 6, and 7
QR Code Encoder / Decoder
Read or generate a QR Code from a text. Can be exported as SVG.
Basic Auth Generator
Generate HTTP Basic Authentication credentials and Authorization header
Hash Calculator
Calculate hashes with native crypto algorithms (MD5, SHA256, SHA512, BLAKE2)
OTP Generator (TOTP/HOTP)
Generate Time-based (TOTP) and Counter-based (HOTP) one-time passwords for 2FA
RSA Key Pair Generator
Generate RSA public/private key pairs in PEM format with configurable key size and hash algorithm
Meta Tag Generator (OG/Twitter)
Generate Open Graph and Twitter Card meta tags for your web pages with live social media previews
MAC Address Generator
Generate random MAC addresses in multiple formats for testing and development
Scrypt Hash Generator
Generate scrypt password hashes with configurable cost parameters for secure password storage
BIP39 Mnemonic Generator
Generate BIP39 mnemonic seed phrases for cryptocurrency wallets with 12 or 24 words
Text
Text Escape / Unescape
Escape or unescape strings to remove special characters that could prevent parsing. Supports JSON, JavaScript, XML, and HTML escaping for safe string handling.
List Comparer
Compare two lists
Line Utilities
Sort lines, remove whitespace, and filter lines from text
HTML Preview
Preview HTML code in a live browser preview
Markdown Preview
Preview a Markdown document with a GitHub-like render
Text Analyzer and Utilities
Analyze text and provide some basic utility tools
Text Comparer
Compare two texts
String Replacer
Find and replace text with regex support
Mermaid Diagram Editor
Write Mermaid diagram syntax and see a live preview of flowcharts, sequence diagrams, class diagrams, and more
Defang / Fang URLs & IPs
Defang URLs and IP addresses for safe sharing in security reports and tickets
Extract URLs / Emails / IPs
Extract all URLs, email addresses, and IP addresses from any text for log analysis and threat hunting
URL Slug Generator
Convert any text to a URL-friendly slug with Unicode support and configurable separators
Prefix / Suffix Lines
Add a prefix or suffix to every line of text for bulk text manipulation
ASCII Art Text Generator
Convert text to ASCII art using FIGlet fonts for terminals, comments, and README files
Documents
Testers
JSONPath Tester
Test a JSONPath
JSON Schema Validator
Validate JSON data against a JSON Schema (draft-04, draft-06, draft-07, 2019-09) with detailed error reporting
IBAN Validator
Validate International Bank Account Numbers (IBAN) with checksum and length
Regular Expression Tester
Validate and test regular expressions
XSD Regex Pattern Tester
Test XSD (XML Schema Definition) regex patterns
URL Parser
Parse and analyze URL components, query parameters, and structure
XML Validator
Validate XML data syntax and structure.
User Agent Parser
Parse and analyze User-Agent strings to extract browser, OS, and device information
Query String Parser
Parse and decode URL query string parameters
XML / XSD Validator
Validate XML documents against XSD schemas online. Check XML syntax, verify schema compliance, test namespace validation, and ensure your XML files meet enterprise standards.
Password Strength Checker
Check password strength, entropy, crack time, and get security recommendations
JSONata Expression Tester
Test JSONata expressions against JSON data with live results and debug JSON queries
Phone Number Parser
Parse and validate international phone numbers with country detection and format conversion
Keyboard Keycode Viewer
Press any key to see its JavaScript keycode, key, code, and which values for debugging keyboard events
Colors
Color Picker & Converter
Pick colors and convert between HEX, RGB, HSL, and HSV formats
Color Contrast Calculator
Calculate color contrast ratio and check WCAG accessibility compliance
Color Blindness Simulator
Simulate color blindness on images for accessibility testing
Color Palette Generator
Generate harmonious color palettes with complementary, analogous, triadic, and tetradic color schemes
Tints & Shades Generator
Generate lighter tints and darker shades from any base color for UI design and branding
Color Palette Extractor
Extract dominant colors from any image and get the main color palette with HEX, RGB, and HSL values
Images
Image Converter
Lossless image converter
Image Compressor
Compress PNG and JPEG images to reduce file size
Image Resizer
Resize images by dimensions or percentage
Image Cropper
Crop images by selecting a rectangular area
Image Boxing
Fit image to canvas with letterbox/pillarbox padding
Image Processor
High-performance image processing with AVIF/HEIF compression. Optimize images, convert formats, and reduce file sizes with enterprise-grade processing capabilities.
References
HTTP Status Codes Reference
Look up any HTTP status code with descriptions, categories, and usage guidance. Complete reference for 1xx, 2xx, 3xx, 4xx, and 5xx codes — free online tool.
MIME Types Lookup
Look up MIME types by type name or file extension. Search all 2500+ registered MIME types with extensions, compressibility, and source — free online reference.
Calculators
Math Expression Evaluator
Evaluate mathematical expressions with variables, functions, and unit conversions
Percentage Calculator
Calculate percentages, percentage change, and percentage of a number instantly
Entropy Calculator
Calculate Shannon entropy and character frequency distribution of any text or data
Technical details
Free Online Developer Tools — DevToys Web Pro
What DevToys Web Pro Is
DevToys Web Pro is a free, browser-based collection of developer tools covering every common task: format and validate JSON, encode and decode Base64, generate UUIDs, decode JWT tokens, test regular expressions, convert between data formats, hash strings, generate QR codes, compress images, and more — all without installing software or sending data to a server. Every tool runs entirely in your browser using JavaScript and WebAssembly, so your code, credentials, and sensitive data never leave your machine.
Tool Categories
Tools are organized into eight categories. Formatters: JSON formatter, SQL formatter, XML formatter, CSS formatter, HTML formatter, JavaScript formatter, YAML formatter, TOML formatter. Encoders & Decoders: Base64 encoder/decoder, URL encoder/decoder, JWT decoder, HTML entity encoder, hex/ASCII converter, Base58, gzip, quoted-printable. Generators: UUID/GUID generator, password generator, QR code generator, hash generator, HMAC generator, RSA key generator, bcrypt generator, lorem ipsum generator, TOTP/OTP generator. Converters: JSON to YAML, JSON to CSV, JSON to TOML, cron expression parser, chmod calculator, date converter, number base converter, curl-to-code, markdown to HTML. Testers: regex tester, JSON Schema validator, JSONPath tester, XML/XSD validator, URL parser, query string parser, IBAN checker, password strength checker. Text tools: markdown preview, text diff/comparer, text analyzer, string replacer, list compare. Image tools: image compressor, image converter, image resizer, image cropper. Network tools: IPv4 subnet calculator, IPv4 range expander, IPv6 parser.
Privacy — Your Data Stays in Your Browser
Unlike many online developer tools that send your input to remote servers for processing, DevToys processes everything locally. When you format JSON, decode a JWT, test a regex, or hash a string, the computation runs in your browser tab using the same JavaScript engine and Web Crypto API that power modern web applications. No data is transmitted, no inputs are logged, and the tools continue working offline after the page loads. This makes DevToys safe to use with JWT tokens, API keys, private keys, credentials, and any other sensitive developer data.
Browser Tool vs Local App
DevToys Web Pro works instantly in any browser with no installation, no login, and no configuration. It is also available as a Progressive Web App (PWA) for offline use, and as a browser extension for Chrome, Firefox, and Edge that puts all tools in your new-tab page. For teams, the web version requires no software deployment — share a URL and anyone on any OS can use the tools immediately. Compared to running scripts locally or configuring VS Code extensions, DevToys is faster to access for one-off formatting, decoding, or conversion tasks.