Free Developer Tools
Fast, privacy-first interactive tools for developers. No signup, no tracking. Just tools that work.
API & Network
15 toolsHTTP API Tester
Send REST API requests directly in your browser. Custom headers, JSON body, response inspection, and request history. No install needed.
API Request Builder
Build and test HTTP requests visually. Generate cURL commands.
API Response Mock Generator
Generate realistic mock API responses with custom status codes, headers, and JSON body. Quick templates for 200, 401, 404, 429, 500 and more.
API Response Formatter & Analyzer
Paste any raw HTTP response to format JSON body, inspect headers, and analyze status codes, CORS, caching, and rate-limit signals instantly.
API Rate Limit Calculator
Convert rate limits across req/s, req/min, req/hr. Calculate delay per worker, burst refill time, and get a Node.js throttle snippet.
HTTP Status Codes
Complete reference for all HTTP status codes with descriptions, use cases, and searchable index.
HTTP Methods Reference
Complete reference for GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS and more. Includes safe/idempotent/cacheable properties and real-world examples.
HTTP Headers Inspector
Inspect HTTP response headers for any URL. See security headers, cache directives, CORS settings, and more — with plain-English explanations for every header.
CORS Tester
Test CORS headers for any URL. Analyze preflight responses and diagnose cross-origin errors.
DNS Lookup Tool
Look up A, AAAA, CNAME, MX, TXT, NS, SOA, and PTR records for any domain using the Cloudflare DNS-over-HTTPS API. Fully client-side.
IP Geolocation Lookup
Look up the geographic location of any IPv4 or IPv6 address — city, country, timezone, ISP, and coordinates. Or detect your own IP.
Timezone Converter
Convert a time across multiple timezones at once. Live world clock, pick source timezone, add destinations, and copy results. No signup needed.
HTTP Code Snippet Generator
Generate HTTP request snippets for cURL, fetch, Axios, Python requests, Go, and PHP. Configure method, URL, headers, and body. One-click copy.
curl Command Builder
Build curl commands visually. Set HTTP method, URL, query params, headers, auth (Bearer, Basic, API key), request body, and options. Copy the ready-to-run command instantly.
WebSocket Tester
Connect to any WebSocket server, send and receive messages in real time, and inspect the message log with timestamps and byte sizes. No install needed.
JSON & Data
17 toolsYAML Validator & Formatter
Validate YAML syntax and see errors by line number. Format with consistent indentation or convert YAML to JSON. Supports mappings, sequences, and nested structures.
JSON Schema Generator
Paste JSON and auto-generate a JSON Schema. Supports Draft-07 and 2020-12. Detects formats like date-time, email, uuid, and uri. Runs in your browser.
JSON Formatter & Validator
Format, beautify, and validate JSON instantly. Choose indent size, minify to one line, or copy the result. Syntax errors highlighted live.
JSON Diff Viewer
Compare two JSON objects side-by-side. Highlight added, removed, and unchanged lines instantly.
JSON to CSV Converter
Convert a JSON array to CSV format. Choose comma, tab, semicolon, or pipe delimiter. Download as .csv file. All processing client-side.
CSV to JSON Converter
Convert CSV data to JSON. Supports comma, tab, semicolon, and pipe delimiters. Output array of objects (with headers) or array of arrays. Download as .json.
CSV Viewer
Paste CSV data and instantly preview it as a formatted table. Supports multiple delimiters, quoted fields, and toggleable header rows.
XML Formatter & Validator
Format messy XML with clean indentation or minify it to reduce size. Invalid XML is caught instantly with a clear error message.
JSON ↔ YAML Converter
Convert between JSON and YAML formats. Handles nested objects, arrays, and all scalar types. Useful for config file migration.
TOML Validator
Validate TOML syntax and see the parsed result as JSON. Useful for Cargo.toml, pyproject.toml, and other TOML config files.
JSON to TypeScript Interface
Paste JSON and get TypeScript interfaces instantly. Handles nested objects, arrays, optional fields, and custom root names. Runs entirely in your browser.
SQL Formatter & Beautifier
Format and indent SQL queries automatically. Uppercase keywords, align clauses, and minify SQL to one line. Supports SELECT, JOIN, CTEs, and more.
HTML Formatter & Minifier
Format messy HTML with proper indentation or minify to reduce file size. Handles void elements, pre/script blocks, and nested tags. Runs in your browser.
CSS Formatter & Minifier
Beautify CSS with consistent indentation or minify to strip whitespace. Supports @media, @keyframes, nested rules. Shows compression savings.
JavaScript Formatter & Minifier
Format JS for readability or minify to reduce bundle size. Preserves strings and template literals. Works with JS, TS, and JSX.
TypeScript to JavaScript
Strip TypeScript type annotations, interfaces, generics, enums, access modifiers, and decorators to get clean JavaScript. Runs in your browser.
TypeScript Playground
Write TypeScript and instantly see compiled JavaScript output. Strip interfaces, generics, enums, and decorators. Share code via URL. No install needed.
Security & Auth
6 toolsJWT Decoder
Decode JWT tokens — inspect header, payload, and claims. Check expiry and iat/sub/iss fields instantly.
JWT Builder
Create HS256 JWT tokens with custom header, payload claims, and secret key. Color-coded output. Great for testing auth flows.
RSA Key Generator
Generate RSA-OAEP key pairs (2048 or 4096-bit) in your browser. Export public and private keys in PEM format. Uses Web Crypto API.
HTTP Security Headers Generator
Toggle and configure HTTP security headers (HSTS, CSP, X-Frame-Options). Generates ready-to-use nginx and Apache configuration snippets.
Hash Generator
Generate MD5, SHA-1, SHA-256, and SHA-512 hashes instantly. All hashing runs in your browser — nothing sent to any server.
Password Generator
Generate cryptographically secure random passwords with custom length and character sets. No data sent to any server.
Code & DevOps
17 toolsRegex Playground
Write, test, and debug regular expressions in real-time with match highlighting.
Regex Tester
Test your regular expressions against multiple strings at once. Batch validate with pass/fail assertions and match highlights. Free, no signup.
Cron Expression Generator
Build and validate cron expressions visually. See next 5 run times in plain English with common presets for hourly, daily, and weekly jobs.
Cron Expression Validator
Validate cron expressions and see a human-readable schedule with the next 5 run times. Field-by-field breakdown and common presets included.
Git Command Builder
Build complex Git commands step by step with all common options.
Git Commit Message Generator
Generate clean commit messages following the Conventional Commits spec. Pick type, scope, description, body, and issue references. Copy in one click.
AI Commit Message Generator
Describe your change in plain English and get commit message suggestions — Conventional Commits, imperative, and bracket-style. Auto-detects type and scope.
Docker Compose Generator
Generate docker-compose.yml configurations visually with templates.
Semver Checker
Parse, compare, and check semantic version ranges. Verify ^, ~, >= constraints, compare two versions, or calculate the next major/minor/patch bump.
.env File Parser
Parse and validate .env files. Detect syntax errors, browse variables, generate a keys-only template, and export shell export commands. Fully client-side.
.gitignore Generator
Generate .gitignore files for Node.js, Python, React, Java, Go, Rust, .NET, and Docker. Select extras like VS Code, macOS, Windows. Download instantly.
package.json Validator & Audit
Paste your package.json to validate syntax and get an audit score. Detects wildcard versions, missing fields, misplaced dependencies, and more.
Code Snippet Share
Paste code and get a shareable URL instantly. Encoded in the URL — no server, no sign-up, no expiry. Share on Slack, Discord, or email.
GitHub Actions Generator
Generate GitHub Actions YAML workflows instantly. Choose triggers, runtime (Node.js, Python, Go, Rust), and jobs (test, lint, build, Docker). Copy-ready CI/CD YAML with best practices.
nginx Config Generator
Generate production-ready nginx server blocks. Supports static sites, reverse proxy, PHP-FPM, HTTPS redirects, SSL/TLS, gzip, cache headers, and security headers.
chmod Calculator
Calculate Unix/Linux file permissions visually. Toggle read/write/execute bits and instantly get octal (755), symbolic (rwxr-xr-x), and the chmod command.
Subnet Calculator
Calculate IPv4 subnet details from CIDR notation. Get network address, subnet mask, broadcast, host range, and total usable hosts. Binary breakdown included.
AI & Productivity
8 toolsAI Token Cost Calculator
Estimate API costs for GPT-4o, Claude 3.5, Gemini 1.5, and more. Enter token counts, character count, or word count and get instant per-call and monthly projections.
Prompt Template Builder
Build reusable AI prompt templates with {slot} variables. Fill values, preview the finished prompt, and export as JSON. Works with ChatGPT, Claude, and Gemini.
AI Test Generator ⚡ Pro
Paste any function or class and get complete unit tests — happy paths, edge cases, and error handling. Supports Jest, Vitest, pytest, and more. Pro feature.
AI Error Explainer ⚡ Pro
Paste any stack trace or error message and get a plain-English explanation plus step-by-step fix instructions. Pro feature.
AI Regex Explainer ⚡ Pro
Paste any regular expression and get a part-by-part breakdown in plain English, match examples, and gotcha warnings. Pro feature.
AI System Guardian
Self-healing monitoring daemon for multi-agent AI systems. 21-pattern deep code scanner, 13 runtime health checks, auto-restart, pipeline stall recovery, and budget alerts.
Pomodoro Timer
Focus timer using the Pomodoro Technique. 25/5/15-minute intervals, sound notifications, session counter. Works offline, no signup needed.
Countdown Timer
Countdown by duration (5 min, 30 min, custom) or to a specific date and time. Great for meetings, deadlines, and sprints. Works offline.
CSS & Design
16 toolsCSS Box Shadow Generator
Build multi-layer CSS box-shadow values visually with live preview. Presets, inset, blur, spread, opacity, and one-click copy.
CSS Gradient Generator
Build linear, radial, and conic CSS gradients visually. Add color stops, adjust angles, and copy the ready-to-use CSS instantly.
CSS Flexbox Visualizer
Interactive flexbox playground. Configure container and item properties with a live preview and generated CSS.
CSS Grid Generator
Build CSS Grid layouts visually. Set columns, rows, gaps, and alignment — click items to control placement. Copy generated CSS in one click.
CSS Unit Converter
Convert between px, rem, em, vw, vh, pt, and % instantly. Configure base font size, viewport, and parent size for accurate relative unit calculations.
CSS Animation Generator
Build CSS keyframe animations with live preview. 10 presets (fade, bounce, shake, spin), configure timing, easing, delay. Copy ready-to-use CSS.
Color Picker & Palette
Pick a color and instantly get HEX, RGB, HSL values. WCAG contrast checker and 5-shade palette generator.
Color Format Converter
Convert colors between HEX, RGB, and HSL formats instantly. Type in any field and all formats update automatically. Visual picker and presets included.
Color Palette Generator
Generate full palettes from any hex color — Tailwind-style shades, complementary, triadic, analogous, and tetradic. Export as CSS custom properties.
Color Blindness Simulator
Preview how colors look with protanopia, deuteranopia, tritanopia, and achromatopsia. Essential for accessible design. Simulates 5 vision types.
Number Formatter
Format any number in 15+ ways: US/EU locale, currencies (USD/EUR/GBP/JPY), scientific notation, binary, hex, octal, words, and file sizes.
Color Contrast Checker
Check foreground/background color contrast ratios against WCAG 2.1 AA and AAA standards. Instant pass/fail results with suggested fixes.
Aspect Ratio Calculator
Calculate simplified aspect ratios, scale dimensions proportionally, and find common screen sizes for any width/height pair. Includes CSS padding-top value.
CSS Border Radius Generator
Build CSS border-radius values visually. Control all four corners individually, use elliptical radii for organic shapes, or pick from 12 presets.
CSS Specificity Calculator
Calculate CSS selector specificity in (inline, ID, class, element) notation. Compare two selectors to see which wins the cascade. All logic runs in your browser.
SVG Editor & Optimizer
Paste, preview, format, and optimize SVG code in your browser. Removes comments, collapses whitespace, shortens hex colors, and reduces file size. Export as data URI.
Text & Encoding
14 toolsBase64 Encoder / Decoder
Encode and decode Base64 strings online. Supports UTF-8 text, URL-safe encoding, and binary data. Runs in your browser.
URL Encoder / Decoder
Encode text to percent-encoded URL format or decode %20 / %3D / %2F sequences back to readable text. Full URL mode supported.
HTML Entity Encoder / Decoder
Encode special characters to HTML entities (< > &) or decode entities back to plain text. Supports 50+ named entities.
String Case Converter
Convert text between camelCase, PascalCase, snake_case, kebab-case, SCREAMING_SNAKE, Title Case, dot.case, and 5 more formats.
Markdown Previewer
Write and preview Markdown in real-time. Supports GFM tables, task lists, and code blocks with syntax hints.
Code Diff Viewer
Compare two code snippets with unified or split side-by-side view. Highlights added/removed lines, shows change counts. Runs in your browser.
Text Diff Checker
Compare two text blocks side-by-side with line-level diff highlighting. Lines added, removed, and unchanged at a glance.
Word Counter
Count words, characters, sentences, paragraphs, and lines. Get reading time estimate and top word frequency. Works on any text instantly.
Line Sorter & Deduplicator
Sort lines A–Z, by length, reverse, or shuffle. Remove duplicates, trim whitespace, and delete empty lines. Perfect for cleaning lists and configs.
HTML to Markdown Converter
Convert HTML to Markdown. Handles headings, bold, italic, links, images, lists, tables, code blocks, and blockquotes. Side-by-side view.
Text ↔ Binary ↔ Hex Converter
Convert between plain text, binary, and hexadecimal. Choose separator, instant conversion, handles ASCII. 4 modes: text↔binary, text↔hex.
URL Parser & Builder
Parse any URL into protocol, hostname, port, path, query parameters, and hash. Or build a URL from parts in the builder mode.
Unicode Character Lookup
Look up any Unicode character by typing it, U+XXXX code point, decimal, or HTML entity. Get UTF-8 bytes, UTF-16, HTML entities, CSS and JS escape sequences instantly.
ASCII Art Generator
Convert any text into ASCII art instantly. Choose from Classic, Blocks, Simple, and Bold styles. Copy and share — runs entirely in your browser.
Converters & Generators
7 toolsUnix Timestamp Converter
Convert between Unix timestamps and human-readable dates. Live clock, timezone support, and instant copy.
Number Base Converter
Convert between binary, octal, decimal, and hexadecimal instantly. Enter any value in any base — all others update automatically.
UUID Generator
Generate UUID v1, v4, and v5 in bulk. Multiple formats: standard, uppercase, no-hyphens, braces. One-click copy.
URL Slug Generator
Convert any title or text into a clean URL-safe slug. Handles accented characters, camelCase, and special characters. Choose hyphen, underscore, or no separator.
Lorem Ipsum Generator
Generate Lorem Ipsum placeholder text — paragraphs, sentences, or words. Start with the classic opening line. Instant copy for mockups and wireframes.
QR Code Generator
Generate QR codes for URLs, WiFi, email, phone, and more. Custom colors, error correction levels, PNG download. No signup, no watermark.
Image to Base64
Convert PNG, JPG, SVG, WebP images to Base64. Get the data URL or CSS background-image value. Drag-and-drop, runs entirely in your browser.
Career & Interviews
8 toolsTech Salary Calculator
Estimate software engineer salary ranges by role, location, and experience level. Covers SF, NYC, Seattle, Remote, London, Berlin, Toronto, and more. No signup.
System Design Cheatsheet
Interactive reference for system design interviews: CAP theorem, load balancers, caching, database types, message queues, consistent hashing, CDNs, and more.
LeetCode Pattern Matcher
Describe your coding problem and instantly surface the matching algorithm pattern — Two Pointers, Sliding Window, BFS, DP, Heap, Trie, Union-Find — with code templates.
Resume Bullet Generator
Generate strong, quantified resume bullet points in STAR format for software engineering roles. 6 achievement templates: built, optimized, led, automated, and more.
Interview Question Generator
Curated interview questions with hints for React, Node.js, Python, Go, TypeScript, SQL, System Design, and Behavioral rounds. Filter by difficulty and type.
Developer Portfolio Checklist
40+ items to build a software engineer portfolio that gets you hired. Foundation, projects, GitHub, SEO, contact. Progress saved in your browser.
Developer Resume Analyzer
Paste your resume text and get an instant score with actionable feedback. Checks contact info, action verbs, metrics, tech keywords, and structure.
Developer Resume Builder
Build an ATS-optimized developer resume section by section. Add experience with impact-driven bullets, projects, skills, and education. Export to Markdown or JSON.
GitHub & Open Source
3 toolsGitHub Stats Card Generator
Generate an embeddable SVG card showing your GitHub repos, total stars, followers, and top languages. Paste into your README — viral loop guaranteed.
Tech Stack Detector
Paste a GitHub repo URL to instantly detect its tech stack — languages, frameworks, databases, testing tools, and DevOps setup. Creates a shareable stack report.
README Generator
Fill in project details and generate a complete README.md with badges, table of contents, features, installation steps, and contributing guide. Download instantly.
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