OpenFormatter

Free Online Developer Tools for Data Formatting

200+ formatters, validators, and converters for JSON, XML, YAML, CSV, HTML & CSS — 100% client-side, nothing you paste ever leaves your browser.

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Your All-in-One Data Formatting Suite

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AI Dev Tools

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AI Token Counter

Exact GPT-4o/GPT-4 token counts, plus Claude and Gemini estimates.

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OpenAI Function Schema Generator

Turn sample JSON into a ready-to-use tool-calling schema.

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MOST USED

JSON Formatter

Beautify, minify, and fix broken JSON structures instantly.

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XML Formatter

Beautify XML with consistent, hierarchical indentation.

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YAML Formatter

Clean up YAML config files with consistent indentation.

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CSS Beautifier

Pretty-print minified or compressed CSS stylesheets.

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JSON Validator

Catch syntax errors and confirm your JSON is well-formed.

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XML Validator

Check XML documents for well-formedness before they ship.

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YAML Validator

Validate YAML syntax and catch indentation errors early.

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OpenAPI Validator

Check an OpenAPI 3.x spec for structural and schema errors.

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YAML to JSON

Convert configuration files seamlessly between formats.

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XML to JSON

Turn XML documents into clean, structured JSON.

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CSV to JSON

Convert spreadsheet exports into nested JSON objects.

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Base64 Encoder

Rapidly encode or decode strings and images to Base64.

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How OpenFormatter Works

Every tool on this site runs entirely inside your browser tab. When you paste JSON, XML, or YAML into an editor, the parsing and formatting logic executes as JavaScript on your own machine — nothing is uploaded to a server, logged, or stored. That's not a privacy policy promise; it's a structural fact of how the site is built: there's no API endpoint for your input to be sent to in the first place.

That local-first design is what makes it safe to paste sensitive input — API keys, database dumps, internal config files — into a tool like this. It also means results are instant: no network round-trip, no server-side upload limit, no queue. OpenFormatter currently covers 200+ tools across JSON, XML, YAML, CSV, HTML, and CSS: formatters, validators, converters, and encoders built around the same workflow — paste, fix, copy, move on.

Runs In Your Browser

No upload, no server round-trip — parsing and formatting happen in JavaScript on your own device.

No Signup, No Limits

Every tool is free to use, with no account, no rate limit, and no paywall.

200+ Tools, One UI

JSON, XML, YAML, CSV, HTML, and CSS — formatters, validators, converters, and encoders in one place.