Developer Tools
80 toolsFormatters, validators, encoders, and reference tools for developers.
The biggest collection on the site: formatters, converters, decoders, and reference sheets for day-to-day development. Everything runs locally, which matters when the thing you are formatting is a production config or a JWT from a real session.
Highlights include a full set of code formatters, JSON tooling in every direction, HTTP and networking helpers, and generators for the boring-but-necessary files like .gitignore, docker-compose, and GitHub Actions workflows.
Most popular
Format & Beautify
- JSON Formatter Format, validate, and minify JSON instantly in your browser. Pretty-print with 2-space, 4-space, or tab indentation. Sort keys alphabetically. Parse errors shown with line and column.
- YAML Formatter Format and validate YAML online. Detect syntax errors, pretty-print with custom indent, and convert JSON to YAML, all in your browser.
- XML Formatter Format, beautify, or minify XML online. Validates well-formedness, highlights errors, and supports custom indentation, all in your browser.
- SQL Formatter Format and beautify SQL online. Supports PostgreSQL, MySQL, T-SQL, SQLite, MariaDB, and PL/SQL. Choose keyword case and indentation, all in your browser.
- HTML Formatter Format and beautify HTML online. Adds indentation, fixes nesting, and optionally self-closes void elements, all in your browser. Nothing is uploaded.
- CSS Formatter Beautify or minify CSS online. Adds indentation and line breaks, or strips whitespace for production, all in your browser. Nothing is uploaded.
- JS Formatter Beautify or minify JavaScript online. Format messy JS with proper indentation, or compress it for production. Runs entirely in your browser.
JSON & Data Conversion
- CSV to JSON Convert CSV to JSON instantly in your browser. Auto-detect delimiter, type inference, header row toggle, and full RFC 4180 quoting support.
- JSON to CSV Convert a JSON array of objects to CSV in your browser. Custom delimiter, quote-all, header toggle, and nested object flattening.
- JSON ↔ YAML Convert JSON to YAML or YAML to JSON instantly in your browser. Supports nested objects, arrays, and all scalar types. No data leaves your device.
- TOML ↔ JSON Converter Convert TOML to JSON or JSON to TOML instantly in your browser. Supports tables, arrays of tables, inline tables, dotted keys, and all TOML scalar types.
- JSON ↔ XML Convert JSON to XML or XML to JSON instantly in the browser. Handles nested objects, arrays, and proper XML entity escaping with a live side-by-side editor.
- JSON -> TS Paste JSON and instantly generate TypeScript interfaces with proper nested types.
- JSON Diff Viewer Compare two JSON objects side-by-side. Instantly see added, removed, changed, and unchanged keys, with support for deeply nested structures.
- JSON Path Tester Test JSONPath expressions against any JSON document in real time. Supports dot notation, wildcards, recursive descent, array slices, and filter expressions.
- JSON Schema Validator Validate any JSON document against a JSON Schema (Draft-07 subset) right in your browser. Supports type, required, properties, allOf/anyOf/oneOf, $ref, format checks, and more.
- CSV Viewer Paste or upload CSV data to view it as a formatted table. Edit cells inline and download the modified CSV.
- Markdown Table Create Markdown tables by filling in a visual grid. Set column alignment, add rows and columns, copy the result.
- Markdown TOC Paste Markdown and generate a table of contents with anchor links. Configure depth and style.
Text, Regex & Bytes
- Regex Tester Live regular expression tester with instant match highlighting, capture groups, replace and split modes, pattern explainer, cheat sheet, and worker-based timeout protection.
- Regex Browse and search a comprehensive regex cheat sheet. Test patterns against sample text instantly.
- Text Diff Compare two texts side by side or in unified format. Highlights added, removed, and modified lines with word- and character-level inline diff. Free, private, runs in your browser.
- String Escaper Escape and unescape strings for JSON, HTML, URL, regex, SQL, and Base64 encoding.
- Unicode Inspect every character in a string: code points, hex, HTML entities, CSS escapes, and categories.
- Byte-Size Counter Count how many bytes a string occupies in UTF-8, UTF-16 LE/BE, and UTF-32 encodings. See which characters are multi-byte and their individual byte sizes.
- Hex Dump Viewer Display the hex dump of typed text or an uploaded file. Shows the byte offset, hexadecimal values, and printable ASCII representation in the classic xxd/od style.
- Box Drawing Generator Generate Unicode box-drawing frames, borders, and ASCII tables. Choose from single, double, rounded, and bold styles. Copy the result for use in terminal output or documentation.
Web & HTTP
- UA Parser Decode any User-Agent string into browser name, version, OS, device type, rendering engine, and CPU architecture, instantly in your browser.
- URL Parser Parse any URL into its components: protocol, hostname, port, path, query parameters, and hash. Decode query strings, inspect domain parts, and build custom URLs.
- Query String Parse URL query strings into key-value tables and build query strings from your own values.
- Cookies Parse Set-Cookie headers and Cookie request headers into structured attribute tables.
- HTTP Header Analyzer Paste HTTP response headers to get instant explanations, security scoring, cookie flag checks, CSP analysis, and actionable recommendations, all offline.
- HTTP Status Codes Searchable reference for all HTTP status codes: 1xx, 2xx, 3xx, 4xx, and 5xx. Find any code by number, name, or description. Includes IANA-registered and commonly used codes.
- MIME Type Lookup Look up MIME types by file extension, or find extensions for a MIME type. Covers 100+ types across images, audio, video, documents, fonts, and more, fully offline.
- cURL Builder Visually build cURL commands without memorising flags. Set the HTTP method, URL, headers, body (JSON, form, raw), and authentication, then copy the ready-to-run command.
- robots.txt Generator Generate a valid robots.txt file for your website. Control which bots can crawl which pages, add sitemap URLs, set crawl delays, and use presets for common configurations.
- Storage Inspector View, add, edit, and delete localStorage and sessionStorage entries in your browser. See the byte size of each key, total storage usage, and switch between storage types.
Network, Git & Infrastructure
- Subnet Calculator Calculate IPv4 subnet properties from an IP + CIDR prefix. Get network address, broadcast, first/last host, subnet mask, wildcard mask, and binary breakdown.
- IPv6 Expander Expand an abbreviated IPv6 address to its full 8-group notation, or compress a full address to its canonical short form. Validates IPv6 syntax including embedded IPv4 addresses.
- Wi-Fi QR Generator Generate a scannable QR code for your Wi-Fi network. Guests can scan it with any modern phone camera to connect instantly - no typing required. Supports WPA, WEP, and open networks.
- Cron Builder Build or decode cron expressions. Type an expression for a plain-English explanation and next 10 run times. Or use the visual builder to create one field by field.
- chmod Calculator Calculate Unix file permissions visually. Toggle read/write/execute bits for owner, group, and other and get the octal code and chmod command.
- Git Commands Browse and search all common Git commands with descriptions and flag references. Copy any command.
- .gitignore Generator Generate .gitignore files for Node, Python, Java, Go, Rust, and 15+ languages, frameworks, and IDEs.
- GitHub Actions Builder Build GitHub Actions CI/CD workflows visually. Configure triggers, Node.js version, package manager, and pipeline steps, then get a ready-to-use .yml file.
- Docker Compose Generator Build docker-compose.yml files visually. Add multiple services with images, ports, environment variables, volumes, depends_on, and restart policies, then copy the generated YAML.
- EditorConfig Generate .editorconfig files with global settings and per-file-type overrides. Copy the output.
- Env File Editor Parse .env files, view all key-value pairs in a clean table, add or edit entries, convert to/from JSON, and copy the result, all in your browser.
Auth, Tokens & Keys
- JWT Decoder Decode any JSON Web Token in your browser: view the header, payload, standard claims, expiry status, and raw base64url parts. Nothing sent to a server.
- JWT Generator Generate and sign JSON Web Tokens (JWT) using HMAC-SHA256 (HS256) entirely in the browser. Edit the payload, set a secret key, and inspect the decoded header, payload, and signature.
- Keypair Generator Generate RSA or Elliptic Curve (ECDSA, ECDH) public/private keypairs in your browser using the Web Crypto API. Export as PEM or JWK. Keys never leave your device.
- Bcrypt Generator Generate bcrypt password hashes and verify passwords against existing hashes entirely in the browser. Supports cost factors 4-14. No data is sent to any server.
- OAuth PKCE Generator Generate OAuth 2.0 PKCE code_verifier and code_challenge (S256) pairs for public clients. Build the complete authorization URL with client ID, redirect URI, scope, and state.
- UUID Inspector Paste any UUID (v1 through v7, Nil, Max) to see its version, variant, embedded timestamp, node address, and a full field-by-field breakdown, fully offline.
- ULID Generator Generate ULIDs (Universally Unique Lexicographically Sortable Identifiers) in the browser. ULIDs combine a millisecond-precision timestamp with cryptographic randomness into a 26-character Crockford Base32 string.
CSS & Design Helpers
- CSS Specificity Calculate and compare CSS selector specificity scores (a,b,c,d). See which rule wins and why, with support for :is(), :not(), :where(), and pseudo-elements.
- PX ↔ REM/EM Convert between px, rem, em, %, and pt for any root and parent font size. Bulk-convert a list of pixel values to get a full CSS unit table instantly.
- PPI Calculator Calculate pixels per inch (PPI), dot pitch, and total pixel count from your screen resolution and diagonal size. See whether your display is retina-class.
- Aspect Ratio Calculator Find a missing width or height from an aspect ratio, simplify any W×H pair to its simplest ratio, or compare two sets of dimensions. Includes presets for 16:9, 4:3, 21:9, and more.
- Type Scale Generator Generate a harmonious typographic scale for any base font size and modular ratio. Output CSS custom properties, Tailwind config values, or a plain table of font sizes.
- CSS Transform Generator Generate CSS 3D transform values visually. Rotate on X/Y/Z axes, scale, skew, translate, and add perspective. See a live preview and copy the generated CSS instantly.
- CSS Transition Visualizer Visualize CSS transitions with an interactive easing curve. Choose a preset (ease, linear, ease-in, ease-out) or define a custom cubic-bezier, set duration and delay, and see the live animation.
- CSS Variable Extractor Paste any CSS and instantly extract all custom properties (CSS variables). View them in a sortable table with their values and selectors, then export as a clean CSS snippet or CSV.
- Media Query Builder Build CSS @media queries visually. Set min/max width, height, orientation, prefers-color-scheme, and more. Preview the result and test against your current viewport.
- Text Shadow Generator Create CSS text-shadow effects with multiple layers. Adjust offset, blur, and color for each layer. Choose from presets like neon glow, emboss, and outline, then copy the generated CSS.
- Font Preview Preview system fonts and web-safe font stacks with custom text. Filter by category (serif, sans-serif, monospace, cursive, fantasy), adjust size and weight, and copy the font-family stack.
- Screen Ruler A free on-screen pixel ruler that shows pixels, inches, centimetres, and millimetres. Enter your screen DPI for accurate physical measurements.
Encode, Convert & Package
- Number Base Converter Convert numbers between binary (base 2), octal (base 8), decimal (base 10), hexadecimal (base 16), and any base 2–36. Uses BigInt for large numbers.
- Data URI Convert text or files to Base64 data URIs for embedding directly in HTML, CSS, or JavaScript.
- Barcode Generator Generate 1-D barcodes in Code 128, Code 39, EAN-13, EAN-8, and UPC-A formats. Preview as SVG, download as PNG. All processing is done in your browser.
- ZIP Creator Create ZIP files directly in your browser. Add text files with custom names and content, then download the archive instantly. No uploads, no server.
- SVG Optimizer Optimize and minify SVG files by removing comments, metadata, whitespace, and empty attributes, all in your browser with instant size savings stats.
- SVG Rasterizer Convert SVG files to PNG or JPEG raster images in your browser. Choose scale factor and background color. No upload, instant download.
References & Cheat Sheets
- ASCII Table Complete, searchable ASCII character table. Look up any character by decimal, hex, octal, binary, abbreviation, or description. Includes control characters, escape sequences, and printable characters.
- ARIA Reference Browse all 50+ WAI-ARIA roles with descriptions and HTML examples. Filter by category (Landmark, Widget, Document) or search by name to find the right role for accessible UI.
- Resistor Color Code Decode resistor color bands to resistance and tolerance, or enter a value to find the matching band colors. Supports 4-band, 5-band, and 6-band resistors.
- SQL JOINs Visualize all 7 SQL JOIN types with Venn diagrams, descriptions, and ready-to-use SQL examples.
- Semver Comparator Compare two semantic version strings (1.2.3, v2.0.0-beta.1) to find which is greater, sort a list of versions, or calculate the next bump.
More Dev tools
- LLM Token Counter Count exact GPT tokens (o200k_base, cl100k_base) plus a labeled Claude estimate. See per-model cost at your own price. Runs entirely in your browser.
- Log Time Annotator Convert log timestamps to local time and add compact elapsed-time annotations. Supports UTC, timezones, custom regex, and formats in your browser.
No tools match your filter.
Try a different keyword, or clear the filter.