Published February 24, 2026 · 20 min read
Developers spend an absurd amount of time searching for simple tools. You need to format a JSON blob, test a regex pattern, decode a JWT, or encode a string to Base64. So you search Google, click the first result, and get hit with a signup wall, a mandatory download, or a "free trial" that requires your credit card. It is 2026 and formatting JSON still requires creating an account on some websites.
This guide is the antidote. We have compiled 80+ free developer tools that you can use instantly in your browser. No signup. No download. No extensions. No paywalls. Just open the URL and start using the tool. Every tool listed here runs entirely client-side — your data never leaves your browser.
We built most of these tools ourselves at SpunkArt because we got tired of the alternatives. Every tool is free, open in the browser, and designed to do one thing well. Bookmark this page — you will use it daily.
The tools developers use most often are data formatting and transformation tools. Parse, format, validate, and convert data structures without leaving your browser.
Paste messy JSON, get beautifully formatted output with syntax highlighting. Validates JSON structure, highlights errors with line numbers, and lets you collapse/expand nested objects. Handles JSON files up to 10MB.
Use cases: Debugging API responses, formatting config files, validating JSON schemas, cleaning up log output.
Open JSON FormatterConvert JSON arrays to CSV for spreadsheet analysis. Handles nested objects, arrays within arrays, and custom delimiters. Export directly to clipboard or download as a .csv file.
Open JSON to CSVTurn CSV data into clean JSON. Auto-detects headers, handles quoted fields, and supports custom separators (comma, tab, semicolon, pipe).
Open CSV to JSONFormat and validate YAML documents. Catches common YAML errors like incorrect indentation, invalid characters, and duplicate keys. Convert between YAML and JSON instantly.
Open YAML FormatterPretty-print XML with proper indentation and syntax highlighting. Validate XML structure and convert between XML and JSON formats.
Open XML FormatterFormat SQL queries for readability. Supports MySQL, PostgreSQL, SQLite, and standard SQL syntax. Handles complex JOINs, subqueries, and CTEs.
Open SQL FormatterWrite Markdown on the left, see rendered HTML on the right. Live preview updates as you type. Supports GitHub Flavored Markdown, tables, code blocks, and task lists.
Open Markdown PreviewWrite, test, and debug code directly in your browser. No IDE setup, no terminal, no configuration.
Test regular expressions in real time against sample text. See matches highlighted instantly. Includes a regex cheat sheet, common patterns library, and support for JavaScript, Python, and PCRE flavors. Explains each part of your regex in plain English.
Why developers love it: Regex is notoriously hard to write correctly. This tool shows you matches, capture groups, and backreferences in real time as you type, eliminating the guess-and-check cycle.
Open Regex TesterWrite and execute JavaScript in your browser. Console output displays below. Supports ES2024+ features, async/await, and module imports. No Node.js installation required.
Open JS PlaygroundThree-pane editor with live preview. Write HTML, CSS, and JavaScript and see the result instantly. Like CodePen but with zero signup and no account needed.
Open Code PlaygroundVisual gradient builder with live preview. Create linear, radial, and conic gradients. Copy the CSS code directly to your clipboard. Includes preset gradients and an angle picker.
Open Gradient GeneratorPick colors visually or convert between HEX, RGB, HSL, and CMYK. Includes contrast ratio checker for WCAG accessibility compliance and palette generation.
Open Color PickerCompress CSS files by removing whitespace, comments, and unnecessary characters. Shows compression ratio and file size reduction. Handles large stylesheets efficiently.
Open CSS MinifierMinify JavaScript code for production. Removes whitespace, shortens variable names, and eliminates dead code. Shows before/after file sizes.
Open JS MinifierGet the complete SpunkArt developer toolkit with source code. Use offline, customize, and deploy on your own server.
Get the Bundle — $9.99 Browse All ToolsTest APIs, inspect requests, and debug network issues without installing Postman or any desktop software.
Send HTTP requests (GET, POST, PUT, DELETE, PATCH) to any API endpoint. Set headers, body, and query parameters. View response headers, status codes, and formatted JSON response. Like Postman but in your browser with zero setup.
Why developers use it: When you need to quickly test an endpoint without firing up a heavy desktop app. Supports authentication headers, custom content types, and request history.
Open API TesterInspect response headers from any URL. See cache headers, security headers, content type, CORS settings, and redirect chains. Essential for debugging deployment issues.
Open Header InspectorEncode and decode URLs and query parameters. Handles special characters, Unicode, and nested query strings. Essential when working with API parameters.
Open URL EncoderConvert cURL commands to JavaScript fetch, Python requests, Go, PHP, and more. Paste a cURL from your browser dev tools and get working code in your language.
Open cURL ConverterEncode, decode, hash, and analyze security tokens. Every tool runs client-side — your secrets never leave your browser.
Paste a JSON Web Token and see the decoded header, payload, and signature. Verify expiration timestamps, inspect claims, and validate token structure. Supports HS256, RS256, and ES256 algorithms.
Privacy guarantee: Your JWT is decoded entirely in your browser using JavaScript. Nothing is sent to any server. This is critical because JWTs contain sensitive authentication data.
Open JWT DecoderEncode text to Base64 or decode Base64 back to text. Supports UTF-8, ASCII, and binary data. Handles data URLs for images and files. Process text or file input up to 50MB.
Open Base64 ToolGenerate cryptographic hashes from text or file input. Supports MD5, SHA-1, SHA-256, SHA-512, and HMAC variants. Compare hashes to verify file integrity.
Open Hash GeneratorGenerate strong, random passwords with custom length, character sets, and entropy calculation. Includes passphrase generator (Diceware) and password strength meter. Check if your password has been exposed in data breaches.
Open Password GeneratorGenerate v4 UUIDs (random) and v7 UUIDs (time-sorted). Bulk generate up to 1,000 UUIDs at once. Parse existing UUIDs to see version and variant information.
Open UUID GeneratorConvert special characters to HTML entities and back. Prevents XSS attacks by properly encoding user input. Supports named entities and numeric character references.
Open HTML EncoderOptimize your websites for speed, search engines, and user experience. No expensive SEO subscriptions required.
Enter any URL and get a comprehensive SEO audit: title tags, meta descriptions, heading structure, image alt text, internal/external links, page speed indicators, and mobile friendliness. Get actionable recommendations to improve your ranking.
Open SEO AnalyzerGenerate optimized meta tags for your web pages. Creates title, description, Open Graph, Twitter Card, and JSON-LD schema markup. Copy and paste directly into your HTML.
Open Meta Tag GeneratorBuild a valid robots.txt file with an interactive builder. Specify allow/disallow rules, crawl delay, and sitemap location. Validate existing robots.txt files for errors.
Open Robots.txt GeneratorGenerate XML sitemaps for your website. Crawl your site, set priority and change frequency for each page, and download the sitemap ready to submit to Google Search Console.
Open Sitemap GeneratorCreate favicons in all required sizes from a single image. Generates ICO, PNG, Apple Touch Icon, and web manifest. One upload, all formats.
Open Favicon GeneratorTransform, analyze, and format text for documentation, content, and development.
Count words, characters, sentences, paragraphs, and reading time. Calculate readability scores (Flesch-Kincaid, Gunning Fog). Identify keyword density and most common words.
Open Word CounterCompare two blocks of text side-by-side. Highlights additions, deletions, and modifications. Supports character-level and word-level diff views. Essential for code reviews and document comparison.
Open Diff CheckerGenerate placeholder text in paragraphs, sentences, or words. Includes standard Lorem Ipsum and alternative generators (Hipster Ipsum, Bacon Ipsum style). Set exact character or word counts.
Open Lorem IpsumConvert text between uppercase, lowercase, title case, sentence case, camelCase, snake_case, kebab-case, and PascalCase. Essential for naming convention conversions in code.
Open Case ConverterConvert any text to a URL-friendly slug. Handles Unicode, removes special characters, and converts spaces to hyphens. Perfect for generating blog post URLs and file names.
Open Slug GeneratorConvert between Unix timestamps, ISO 8601 dates, and human-readable formats. See the current timestamp in real time. Supports milliseconds and seconds precision.
Open Timestamp ConverterGenerate QR codes from URLs, text, WiFi credentials, contact cards, and more. Download as PNG or SVG. Customize colors and size.
Open QR GeneratorCompress PNG, JPG, and WebP images directly in your browser. Adjust quality level with live preview. Reduce file sizes by 50-90% with negligible quality loss. Your images stay on your device.
Open Image CompressorConvert numbers between binary, octal, decimal, and hexadecimal. Supports large numbers and shows step-by-step conversion logic.
Open Base ConverterThere is a growing movement in the developer community against unnecessary accounts and data collection. Here is why free developer tools with no signup are important:
Create a browser bookmarks folder called "Dev Tools" and add the tools from this list that you use most. You will save hours per week by going directly to the tool instead of searching for it every time. Or bookmark spunk.codes — all 80+ tools are accessible from the homepage.
Every tool listed above is free to use online at spunk.codes. For developers who want offline access, source code, and the ability to customize and self-host, we offer the complete toolkit as a one-time purchase:
What you get: 80+ tools with full HTML/CSS/JS source code, offline access, no branding, white-label rights, and lifetime updates. Deploy on your own server, embed in your projects, or use offline on a plane.
Price: $9.99 one-time (no subscription)
Get the BundleJSON, regex, JWT, API, Base64, SEO, and dozens more. All free. All in your browser. No signup.
Open SpunkArt Tools Get Offline Bundle80+ free tools
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