JSON Formatter & Validator
Format, validate, and beautify your JSON data instantly.
About the Private JSON Formatter & Validator - Fast, Client-Side Data Tool
This JSON formatter parses, validates, and pretty-prints JSON entirely in your browser using the native JavaScript JSON parser — no API calls, no server logging, no telemetry. Paste a minified API response, a config file, or a JWT payload and get human-readable JSON with two-space indentation in milliseconds. Syntax errors surface inline with the underlying parser message so you can spot the broken comma, unclosed brace, or stray quote without guessing. Because every byte is processed locally, this is safe to use on private payloads like authentication tokens, internal logs, and customer data that you cannot share with hosted formatters.
What people use it for
- Beautify minified API responses for debugging
- Validate JSON config files (package.json, tsconfig.json, manifest.json)
- Inspect JWT payloads and OAuth responses without leaking secrets
- Format webhook payloads from Stripe, GitHub, and Slack
- Clean up scraped or copy-pasted JSON before committing to a repo
Private by design
Everything you type here is processed inside your browser. Nothing is sent to a server, logged or stored, so it is safe to use with real numbers, drafts and anything you would not paste into a hosted tool.
Try these next
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- JSON to YAML Converter — Convert Online for Free Convert JSON to YAML and YAML to JSON instantly. Bidirectional converter with syntax validation and error highlighting. Free, private, browser-based tool for developers.
- JWT Decoder Decode JSON Web Tokens locally in your browser. Inspect the header, payload claims, expiration time, and raw signature. Tokens never leave your device — safe for prod auth tokens.
- Base64 Encoder/Decoder Encode and decode Base64 strings in your browser. Handles UTF-8, emoji, and binary safely via TextEncoder. Use for data URIs, JWT inspection, and Basic Auth headers.
Browse every tool or read the creator guides.
Questions people ask
How do I format JSON online?
Paste your JSON into the input field and the tool will automatically format and validate it with proper indentation. No sign-up or installation required.
Is this JSON formatter free to use?
Yes, this JSON formatter is 100% free. It runs entirely in your browser, so your data never leaves your device.
Can I validate JSON syntax with this tool?
Absolutely. The tool highlights syntax errors in real-time, showing you exactly where the issue is in your JSON data.
Is this a private JSON formatter?
Yes. This is a fully client-side JSON formatter — your data is processed in your browser and never sent to any server, making it a privacy-first tool for sensitive JSON data.