Published March 22, 2026 · 22 min read
Developer tool subscriptions add up fast. Postman at $14/month. Semrush at $130/month. Adobe Creative Cloud at $55/month. Before you know it, you are spending thousands of dollars per year on tools that you only use a fraction of.
Here is the alternative: 100 completely free developer tools that work instantly in your browser. No signup forms. No email verification. No credit card trials. No desktop downloads. Just open the page and start working.
Every tool listed here is available on SPUNK.CODES right now. We built them because we were tired of paying for basic utilities that should be free. These are not watered-down demos -- they are full-featured tools that handle real production work.
SEO tools are the most overpriced category in developer software. Ahrefs charges $99/month for their cheapest plan. Semrush starts at $130/month. Moz Pro costs $99/month. These tools below cover the SEO tasks that 90% of developers and marketers need daily.
| # | Tool | What It Does | Link |
|---|---|---|---|
| 1 | Meta Tag Analyzer | Audits title, description, OG tags, and Twitter cards for any URL | Use Free |
| 2 | Sitemap Generator | Creates XML sitemaps with priority and changefreq settings | Use Free |
| 3 | Robots.txt Tester | Validates robots.txt syntax and simulates crawler behavior | Use Free |
| 4 | Keyword Density Checker | Analyzes keyword frequency, prominence, and distribution in content | Use Free |
| 5 | Schema Markup Generator | Generates JSON-LD structured data for articles, products, FAQs, and more | Use Free |
| 6 | Open Graph Previewer | Shows exactly how your page looks when shared on Facebook, Twitter, LinkedIn | Use Free |
| 7 | SERP Preview Tool | Previews how your page title and description appear in Google search results | Use Free |
| 8 | Heading Structure Checker | Validates H1-H6 hierarchy and flags SEO issues in heading order | Use Free |
| 9 | Canonical URL Checker | Verifies canonical tags and detects duplicate content issues | Use Free |
| 10 | Page Speed Analyzer | Measures load time, resource sizes, and gives optimization tips | Use Free |
| 11 | Redirect Checker | Traces redirect chains and identifies 301 vs 302 redirects | Use Free |
| 12 | Backlink Checker | Shows backlinks pointing to any domain using public data | Use Free |
| 13 | Slug Generator | Converts titles to SEO-friendly URL slugs with custom separators | Use Free |
| 14 | Hreflang Tag Generator | Creates hreflang tags for multilingual websites | Use Free |
| 15 | Core Web Vitals Checker | Tests LCP, FID, and CLS metrics against Google thresholds | Use Free |
Paid alternative cost: Ahrefs ($99/mo) + Semrush ($130/mo) = $2,748/year saved
JSON is the backbone of modern web development. Every API response, every config file, every data exchange uses JSON. These tools make working with JSON painless.
| # | Tool | What It Does | Link |
|---|---|---|---|
| 16 | JSON Formatter | Pretty-prints JSON with syntax highlighting, indentation control, and line numbers | Use Free |
| 17 | JSON Validator | Validates JSON syntax and pinpoints exact error locations with line numbers | Use Free |
| 18 | JSON Minifier | Removes whitespace and formatting to reduce JSON file size | Use Free |
| 19 | JSON to CSV Converter | Converts JSON arrays to downloadable CSV files | Use Free |
| 20 | JSON to XML Converter | Transforms JSON data to well-formed XML documents | Use Free |
| 21 | JSON Diff Tool | Compares two JSON objects and highlights additions, deletions, and changes | Use Free |
| 22 | JSON Path Finder | Navigates nested JSON with JSONPath queries and visual tree explorer | Use Free |
| 23 | JSON to YAML Converter | Converts JSON to YAML format for Kubernetes, Docker, and CI/CD configs | Use Free |
| 24 | JSON Schema Generator | Auto-generates JSON Schema from sample JSON data | Use Free |
| 25 | JSON Tree Viewer | Visualizes JSON as a collapsible tree with search and filter | Use Free |
CSS tools save hours of manual tweaking. Generate gradients, shadows, grid layouts, and animations visually instead of guessing pixel values.
| # | Tool | What It Does | Link |
|---|---|---|---|
| 26 | CSS Gradient Generator | Creates linear, radial, and conic gradients with visual editor and CSS output | Use Free |
| 27 | CSS Box Shadow Generator | Visual box-shadow editor with multiple layers, blur, spread, and color | Use Free |
| 28 | CSS Flexbox Playground | Interactive flexbox layout builder with live preview and CSS code export | Use Free |
| 29 | CSS Grid Generator | Visual CSS Grid builder with template areas, gap controls, and responsive preview | Use Free |
| 30 | CSS Minifier | Compresses CSS by removing whitespace, comments, and redundant code | Use Free |
| 31 | CSS Animation Generator | Creates keyframe animations with visual timeline and easing controls | Use Free |
| 32 | CSS Border Radius Generator | Advanced border-radius tool for creating organic shapes and blobs | Use Free |
| 33 | CSS Text Shadow Generator | Layered text-shadow editor with glow, emboss, and retro effects | Use Free |
| 34 | CSS Filter Generator | Visual CSS filter editor: blur, brightness, contrast, hue-rotate, and more | Use Free |
| 35 | CSS Clip Path Generator | Creates clip-path polygons, circles, and ellipses with visual editor | Use Free |
Image optimization is critical for web performance. These tools handle compression, conversion, resizing, and format changes without uploading your images to a server.
| # | Tool | What It Does | Link |
|---|---|---|---|
| 36 | Image Compressor | Reduces image file size while maintaining quality using client-side compression | Use Free |
| 37 | Image Resizer | Resizes images by pixels or percentage with aspect ratio lock | Use Free |
| 38 | PNG to JPG Converter | Converts PNG images to JPG with quality control | Use Free |
| 39 | SVG to PNG Converter | Renders SVG files to PNG at any resolution | Use Free |
| 40 | Image to Base64 Converter | Encodes images as Base64 strings for embedding in CSS and HTML | Use Free |
| 41 | Favicon Generator | Creates favicons in ICO, PNG, and SVG formats from any image | Use Free |
| 42 | Image Color Picker | Extracts HEX, RGB, and HSL color values from any uploaded image | Use Free |
| 43 | QR Code Generator | Generates QR codes for URLs, text, WiFi, vCards, and more | Use Free |
| 44 | Screenshot to Code | Converts UI screenshots into HTML and CSS code approximations | Use Free |
| 45 | Image EXIF Viewer | Reads and displays EXIF metadata from photos including GPS, camera settings | Use Free |
Text manipulation is one of the most common developer tasks. These tools handle encoding, formatting, comparison, and transformation without writing scripts.
| # | Tool | What It Does | Link |
|---|---|---|---|
| 46 | Text Diff Checker | Compares two text blocks side-by-side and highlights every difference | Use Free |
| 47 | Word Counter | Counts words, characters, sentences, paragraphs, and reading time | Use Free |
| 48 | URL Encoder/Decoder | Encodes and decodes URL components including query strings | Use Free |
| 49 | Base64 Encoder/Decoder | Encodes text to Base64 and decodes Base64 strings back to text | Use Free |
| 50 | HTML Entity Encoder | Converts special characters to HTML entities and vice versa | Use Free |
| 51 | Lorem Ipsum Generator | Generates placeholder text by words, sentences, or paragraphs | Use Free |
| 52 | Markdown to HTML Converter | Converts Markdown syntax to clean, semantic HTML | Use Free |
| 53 | HTML to Markdown Converter | Reverses HTML back to clean Markdown syntax | Use Free |
| 54 | Case Converter | Converts text between UPPER, lower, Title, camelCase, snake_case, kebab-case | Use Free |
| 55 | String Escape/Unescape | Escapes and unescapes strings for JSON, HTML, JavaScript, and SQL | Use Free |
Code formatting, validation, and conversion tools that every developer reaches for daily. No IDE plugins needed -- these run in your browser.
| # | Tool | What It Does | Link |
|---|---|---|---|
| 56 | Regex Tester | Tests regular expressions with real-time matching, groups, and explanations | Use Free |
| 57 | HTML Formatter | Beautifies and indents HTML code with customizable indent width | Use Free |
| 58 | JavaScript Minifier | Minifies JavaScript by removing whitespace, shortening variables | Use Free |
| 59 | SQL Formatter | Formats SQL queries with proper indentation and keyword highlighting | Use Free |
| 60 | Cron Expression Parser | Converts cron expressions to human-readable schedules and vice versa | Use Free |
| 61 | HTML to JSX Converter | Converts HTML attributes to JSX syntax (class to className, etc.) | Use Free |
| 62 | Code Snippet Beautifier | Formats code in 15+ languages with consistent style | Use Free |
| 63 | Git Command Generator | Builds complex Git commands with a visual form interface | Use Free |
| 64 | YAML Validator | Validates YAML syntax and converts between YAML and JSON | Use Free |
| 65 | TOML to JSON Converter | Converts TOML config files to JSON and vice versa | Use Free |
API development and testing tools. The free Postman alternative category that saves you $14/user/month.
| # | Tool | What It Does | Link |
|---|---|---|---|
| 66 | API Tester | Send GET, POST, PUT, DELETE requests with custom headers and auth | Use Free |
| 67 | JWT Decoder | Decodes JSON Web Tokens and displays header, payload, and signature | Use Free |
| 68 | HTTP Header Analyzer | Inspects HTTP response headers for security, caching, and CORS issues | Use Free |
| 69 | Webhook Tester | Creates temporary webhook endpoints to capture and inspect incoming requests | Use Free |
| 70 | CORS Tester | Tests CORS configuration for any URL and reports allowed origins and methods | Use Free |
| 71 | GraphQL Explorer | Interactive GraphQL query builder with schema introspection | Use Free |
| 72 | cURL to Code Converter | Converts cURL commands to Python, JavaScript, PHP, Go, and more | Use Free |
| 73 | API Response Timer | Measures API response time across multiple sequential requests | Use Free |
| 74 | OAuth Token Generator | Generates OAuth 2.0 tokens for testing protected API endpoints | Use Free |
| 75 | API Documentation Generator | Creates OpenAPI/Swagger docs from API endpoint descriptions | Use Free |
Security is not optional. These tools help you generate strong passwords, hash data, check for vulnerabilities, and encode sensitive information.
| # | Tool | What It Does | Link |
|---|---|---|---|
| 76 | Password Generator | Creates cryptographically secure passwords with custom length and character sets | Use Free |
| 77 | Hash Generator | Generates MD5, SHA-1, SHA-256, SHA-512 hashes from text input | Use Free |
| 78 | SSL Certificate Checker | Inspects SSL/TLS certificates for expiry, chain, and configuration issues | Use Free |
| 79 | CSP Generator | Builds Content Security Policy headers with visual policy editor | Use Free |
| 80 | UUID Generator | Generates UUID v1, v4, and v7 identifiers in bulk | Use Free |
| 81 | Security Header Scanner | Scans any URL and grades its HTTP security headers | Use Free |
| 82 | HMAC Generator | Creates HMAC signatures using SHA-256, SHA-512, and other algorithms | Use Free |
| 83 | Password Strength Checker | Analyzes password entropy, crack time estimates, and common pattern detection | Use Free |
| 84 | RSA Key Pair Generator | Generates RSA public/private key pairs for encryption and signing | Use Free |
| 85 | Bcrypt Hash Generator | Creates bcrypt password hashes with configurable salt rounds | Use Free |
For serious crypto security, protect your assets with a hardware wallet. Ledger hardware wallets keep your private keys offline and safe from hackers.
Number crunching, unit conversion, and data transformation tools for when you need quick calculations without opening a spreadsheet.
| # | Tool | What It Does | Link |
|---|---|---|---|
| 86 | Number Base Converter | Converts between binary, octal, decimal, and hexadecimal | Use Free |
| 87 | Unix Timestamp Converter | Converts between Unix timestamps and human-readable dates | Use Free |
| 88 | Byte Converter | Converts between bytes, KB, MB, GB, TB with binary and decimal units | Use Free |
| 89 | Percentage Calculator | Calculates percentages, increases, decreases, and differences | Use Free |
| 90 | CSV to JSON Converter | Transforms CSV data into structured JSON arrays and objects | Use Free |
| 91 | IP Address Lookup | Shows geolocation, ISP, ASN, and reverse DNS for any IP address | Use Free |
| 92 | Epoch Converter | Converts epoch milliseconds to date strings across time zones | Use Free |
Color is design. These tools help you pick, convert, generate, and visualize color palettes for web projects.
| # | Tool | What It Does | Link |
|---|---|---|---|
| 93 | Color Palette Generator | Generates harmonious color palettes with complementary, analogous, and triadic schemes | Use Free |
| 94 | HEX to RGB Converter | Converts between HEX, RGB, HSL, and CMYK color formats | Use Free |
| 95 | Color Contrast Checker | Tests WCAG 2.1 contrast ratios for accessibility compliance (AA/AAA) | Use Free |
| 96 | Gradient CSS Generator | Creates multi-stop CSS gradients with angle and position controls | Use Free |
| 97 | Color Blindness Simulator | Simulates how designs appear to users with various types of color blindness | Use Free |
| 98 | Tailwind Color Finder | Finds the closest Tailwind CSS color class for any HEX value | Use Free |
| 99 | Color Mixer | Blends two colors together with adjustable ratio and outputs all formats | Use Free |
| 100 | Brand Color Extractor | Extracts the dominant color palette from any website URL | Use Free |
Here is the real cost of the tools most developers pay for -- and what you save using SPUNK.CODES instead.
| Category | Paid Tool | Monthly Cost | Annual Cost | SPUNK.CODES |
|---|---|---|---|---|
| SEO Suite | Semrush | $129.95/mo | $1,559/yr | $0 (15 tools) |
| SEO Suite | Ahrefs | $99/mo | $1,188/yr | $0 (15 tools) |
| API Testing | Postman Pro | $14/mo | $168/yr | $0 (10 tools) |
| Design | Adobe CC | $54.99/mo | $660/yr | $0 (10 tools) |
| JSON/Code | JetBrains | $24.90/mo | $299/yr | $0 (20 tools) |
| Security | 1Password Teams | $7.99/mo | $96/yr | $0 (10 tools) |
| Total Annual Savings: | $3,970+/year | |||
These are not toy tools. They handle the same tasks that the paid alternatives do. The difference is that SPUNK.CODES tools run in your browser with zero accounts, zero tracking, and zero cost. Your data never leaves your machine.
Start using any tool instantly. No email required. No credit card. No trial period.
Browse All 647+ ToolsWe run SpunkArt, a network of over 220 websites. We needed developer tools every single day -- SEO checkers, JSON formatters, image compressors, color converters. And we were tired of three things:
So we built every tool we needed and made them all free. No strings attached. That collection grew to over 647 tools and counting.