💻 Best Free Developer & Code Tools Online
Format JSON, validate XML, test regex, preview HTML, edit Markdown, and more with these free online developer tools.
Developer Tools (8 Tools)
JSON Formatter
Beautify and validate JSON with customizable indentation.
Use case: Data formatting →
JSON Validator
Validate JSON syntax and structure instantly.
Use case: Error detection →
XML Formatter
Pretty-print and indent XML documents.
Use case: XML formatting →
XML Validator
Validate XML structure and syntax.
Use case: Error detection →
Markdown Editor
Write Markdown with live HTML preview side by side.
Use case: Documentation, blogging →
Markdown Preview
Convert Markdown to HTML output instantly.
Use case: Content conversion →
HTML Previewer
Preview HTML code with live rendering in browser.
Use case: Web development →
Regex Tester
Test regular expressions with match highlighting.
Use case: Pattern matching →
Frequently Asked Questions
What is a JSON formatter? ▼
A JSON formatter takes raw JSON data and formats it with proper indentation, making it readable and easy to debug. Our tool supports 2-space, 4-space, and tab indentation options.
How do I validate JSON? ▼
Paste your JSON into our JSON Validator tool. It will immediately check for syntax errors, missing commas, incorrect brackets, and other common issues. If valid, it confirms the structure is correct.
What is Markdown? ▼
Markdown is a lightweight markup language created by John Gruber. It uses simple syntax (like # for headers, ** for bold, and - for lists) to create formatted text that converts to HTML. It's used for documentation, README files, and blogging.
How do I test regular expressions? ▼
Use our Regex Tester tool. Enter your regex pattern and test string. The tool highlights matches in real time and shows capture groups. This is invaluable for debugging complex patterns.
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About Developer Tools
Our collection of developer tools includes 8 free online tools designed for writers, developers, and SEO professionals. All tools run entirely in your browser — no data is uploaded to any server. Your text stays private and secure.
Each tool is designed for speed and accuracy. Simply paste your text, click a button, and get instant results. No sign-up required. No ads. No tracking. Just fast, free tools that work.