A curated list of free developer tools, services, and resources. All tools listed are free to use with no mandatory signup.
- JSON & Data Tools
- Encoders & Decoders
- Hashing & Crypto
- CSS & Design Tools
- Color Tools
- Text & Content Tools
- Image Tools
- Converters
- Network & DNS Tools
- SEO & Meta Tools
- DevOps & Config
- API & Testing Tools
- Code Formatters
- Reference & Cheatsheets
- Finance Calculators
- General Purpose
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit JSON Formatter | Format, validate, and minify JSON with syntax error detection | Yes |
| ZeroKit JSONPath | Evaluate JSONPath expressions against JSON data | Yes |
| ZeroKit JSON Diff | Compare two JSON documents side by side | Yes |
| ZeroKit JSON Tree | Interactive JSON tree viewer with search | Yes |
| ZeroKit JSON Schema | Validate JSON against JSON Schema | Yes |
| ZeroKit JSON to YAML | Convert between JSON and YAML | Yes |
| ZeroKit JSON to CSV | Convert between JSON arrays and CSV | Yes |
| ZeroKit JSON to TypeScript | Generate TypeScript interfaces from JSON | Yes |
| ZeroKit JSON Schema Generator | Generate JSON Schema from JSON data | Yes |
| JSONLint | JSON validator and formatter | Yes |
| JSON Editor Online | View, edit, format, and validate JSON | Yes |
| jq play | A playground for jq, the command-line JSON processor | No |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit Base64 | Encode and decode Base64 strings | Yes |
| ZeroKit Base58 | Encode and decode Base58/Base62 | Yes |
| ZeroKit URL Encoder | Encode and decode URL components | Yes |
| ZeroKit HTML Entity | Convert special characters to HTML entities | Yes |
| ZeroKit JWT Decoder | Decode and inspect JWT payloads | Yes |
| ZeroKit JWT Builder | Build and sign JWT tokens | Yes |
| ZeroKit Data URL | Create and decode data URLs | Yes |
| ZeroKit Encoding Converter | Convert between UTF-8, ASCII, Latin-1 with hex dump | Yes |
| jwt.io | JWT debugger and library list | Yes |
| CyberChef | The Cyber Swiss Army Knife - encoding, encryption, and more | Yes |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit Hash Generator | Generate MD5, SHA-1, SHA-256, SHA-512 hashes | Yes |
| ZeroKit HMAC Generator | Generate HMAC signatures | Yes |
| ZeroKit Password Generator | Create strong passwords with custom rules | Yes |
| ZeroKit SSH Key Generator | Generate SSH key pairs | Yes |
| ZeroKit UUID Generator | Generate v4 UUIDs | Yes |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit Flexbox Generator | Visual CSS Flexbox layout builder | Yes |
| ZeroKit CSS Grid | Visual CSS Grid layout builder | Yes |
| ZeroKit Gradient Builder | Design CSS gradients visually | Yes |
| ZeroKit Box Shadow | CSS box shadow generator with live preview | Yes |
| ZeroKit Border Radius | Visual border radius editor | Yes |
| ZeroKit Text Shadow | CSS text shadow generator | Yes |
| ZeroKit CSS Animation | CSS animation keyframe builder | Yes |
| ZeroKit Clip-Path | Visual CSS clip-path editor | Yes |
| ZeroKit CSS Filter | CSS filter effects generator | Yes |
| ZeroKit CSS Specificity | CSS selector specificity calculator | Yes |
| ZeroKit Tailwind Lookup | Search Tailwind CSS classes | Yes |
| CSS-Tricks Flexbox Guide | Comprehensive Flexbox guide | N/A |
| Neumorphism.io | Neumorphism CSS generator | Yes |
| Animista | CSS animation playground | Yes |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit Color Converter | Convert between HEX, RGB, HSL | Yes |
| ZeroKit Color Picker | Advanced color picker | Yes |
| ZeroKit Palette Generator | Generate harmonious color palettes | Yes |
| ZeroKit Contrast Checker | WCAG contrast ratio checker | Yes |
| ZeroKit Color Blindness | Simulate color blindness | Yes |
| ZeroKit HTML Colors | All 141 CSS named colors | Yes |
| Coolors | Color palette generator | Yes |
| Contrast Ratio | WCAG contrast ratio tool by Lea Verou | Yes |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit Word Counter | Count words, characters, reading time | Yes |
| ZeroKit Text Case | Convert between camelCase, snake_case, etc. | Yes |
| ZeroKit Text Diff | Compare two blocks of text | Yes |
| ZeroKit Regex Tester | Test regular expressions with live matching | Yes |
| ZeroKit Markdown Preview | Live Markdown preview | Yes |
| ZeroKit Markdown to HTML | Convert Markdown to HTML | Yes |
| ZeroKit Lorem Ipsum | Generate placeholder text | Yes |
| ZeroKit ASCII Art | Generate ASCII art from text | Yes |
| ZeroKit Emoji Picker | Search and copy emojis | Yes |
| ZeroKit Font Preview | Preview Google Fonts | Yes |
| Regex101 | Regex tester with explanation | Yes |
| Hemingway Editor | Writing clarity checker | Yes |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit Image Compressor | Compress images in the browser | Yes |
| ZeroKit SVG Optimizer | Optimize and minify SVG files | Yes |
| ZeroKit Placeholder Image | Generate placeholder images | Yes |
| ZeroKit Favicon Generator | Create favicons from text or images | Yes |
| ZeroKit QR Code | Generate QR codes | Yes |
| ZeroKit Image to Base64 | Convert images to Base64 data URIs | Yes |
| Squoosh | Image compression by Google | Yes |
| SVGOMG | SVG optimizer GUI | Yes |
| TinyPNG | PNG/JPEG compression | No |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit HTML to Markdown | Convert HTML to Markdown | Yes |
| ZeroKit SQL to MongoDB | Convert SQL queries to MongoDB | Yes |
| ZeroKit cURL to Code | Convert cURL commands to code | Yes |
| ZeroKit Timestamp | Convert Unix timestamps | Yes |
| ZeroKit Base Converter | Convert between number bases | Yes |
| ZeroKit IP Converter | Convert IP address formats | Yes |
| ZeroKit TOML Converter | Convert between TOML and JSON | Yes |
| ZeroKit Text to Binary | Convert text to binary | Yes |
| ZeroKit XML Formatter | Format, validate, minify XML | Yes |
| Transform Tools | Multi-format converter (JSON, GraphQL, etc.) | Yes |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit DNS Lookup | Resolve DNS records (A, AAAA, MX, PTR) | No |
| ZeroKit SSL Checker | Verify SSL certificates | No |
| ZeroKit HTTP Headers | Inspect HTTP response headers | No |
| ZeroKit WHOIS | Domain registration information | No |
| ZeroKit Redirect Checker | Trace redirect chains | No |
| ZeroKit Status Checker | Check if a website is up | No |
| ZeroKit Email Validator | Validate email via MX records | No |
| ZeroKit Tech Detector | Detect website tech stack | No |
| ZeroKit IP Info | Your public IP, browser, OS info | Yes |
| ZeroKit Subnet Calculator | Calculate subnet ranges | Yes |
| ZeroKit Network Ports | 108 common port reference | Yes |
| MXToolbox | DNS, MX, and blacklist lookups | No |
| SSL Labs | Deep SSL/TLS analysis | No |
| BuiltWith | Technology profiler | No |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit Meta Tag Generator | Generate HTML meta tags | Yes |
| ZeroKit OG Preview | Preview Open Graph tags | Yes |
| ZeroKit Robots.txt Generator | Generate robots.txt files | Yes |
| ZeroKit GitHub Profile | Generate GitHub profile READMEs | Yes |
| Metatags.io | Meta tag preview and generator | Yes |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit Cron Generator | Build cron schedule expressions | Yes |
| ZeroKit Crontab Tester | Test crontab entries | Yes |
| ZeroKit Docker Compose | Docker Compose generator | Yes |
| ZeroKit Nginx Config | Nginx configuration generator | Yes |
| ZeroKit .htaccess | .htaccess rule generator | Yes |
| ZeroKit PWA Manifest | PWA manifest.json generator | Yes |
| ZeroKit .env Editor | Environment file editor | Yes |
| ZeroKit Chmod | Unix permission calculator | Yes |
| Crontab.guru | Cron expression editor | Yes |
| Nginx Config Generator | DigitalOcean Nginx tool | Yes |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit API Tester | Test REST API endpoints | Yes |
| ZeroKit SemVer Checker | Semantic versioning tool | Yes |
| Hoppscotch | Open-source API development | Yes |
| Httpbin | HTTP request/response service | No |
| Webhook.site | Test webhooks and HTTP requests | No |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit SQL Formatter | Beautify SQL queries | Yes |
| ZeroKit HTML Formatter | Format HTML markup | Yes |
| ZeroKit CSS/JS Minifier | Minify CSS and JavaScript | Yes |
| ZeroKit CSV Viewer | View and explore CSV files | Yes |
| Prettier Playground | Code formatter playground | Yes |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit HTTP Status Codes | Complete HTTP status code reference | Yes |
| ZeroKit HTTP Methods | HTTP methods reference | Yes |
| ZeroKit Git Cheatsheet | Interactive Git reference | Yes |
| ZeroKit SQL Reference | SQL syntax quick reference | Yes |
| ZeroKit Regex Reference | Regex syntax cheatsheet | Yes |
| ZeroKit CSS Units | CSS units reference | Yes |
| ZeroKit Keyboard Shortcuts | Common keyboard shortcuts | Yes |
| DevDocs | API documentation browser | Yes |
| OverAPI | Cheatsheet aggregator | N/A |
| Tool | Description | Client-Side |
|---|---|---|
| ZeroKit Mortgage Calculator | Monthly payment + amortization schedule | Yes |
| ZeroKit Compound Interest | Compound interest with charts | Yes |
| ZeroKit Salary Calculator | Annual/monthly/hourly conversion | Yes |
| ZeroKit ROI Calculator | Return on investment calculator | Yes |
| ZeroKit Loan Calculator | Auto/personal loan payments | Yes |
| ZeroKit BMI Calculator | Body Mass Index with WHO scale | Yes |
| ZeroKit Percentage | Percentage calculations | Yes |
| ZeroKit Tip Calculator | Tip + bill splitting | Yes |
| Tool | Description | Client-Side |
|---|---|---|
| UptimePulse | Free website uptime monitoring with status pages and SVG badges | No |
| UptimeRobot | Website monitoring with 5-minute checks | No |
| Uptime Kuma | Self-hosted monitoring tool | No |
| Tool | Description |
|---|---|
| ZeroKit.dev | 117 free developer tools in one place |
| ZeroKit Finance Calculators | Free online calculators (mortgage, ROI, salary, and more) |
| DevDocs | Unified API documentation |
| Can I Use | Browser support tables |
| Bundlephobia | npm package size checker |
| Carbon | Beautiful code screenshots |
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