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Check JSON syntax instantly. Auto-validates as you type. Your data never leaves your browser.
JSON Input
Pro tip
Catch JSON config errors before they reach production. Git AutoReview validates JSON changes in PRs and explains what broke.
Paste your JSON into the editor and the validator checks it automatically as you type. You can also press Ctrl+Enter to validate manually, or drag and drop a .json file onto the page.
If the JSON is valid, you see a green checkmark with stats: the root type (object or array), number of top-level keys or items, nesting depth, and file size. If invalid, you get the exact error message from the parser showing what went wrong and where.
Config file changes are the most common case. When you edit tsconfig.json, package.json, .eslintrc, or any CI/CD pipeline config, a single misplaced comma can break your entire build. Validating before committing saves you from a failed CI run and an embarrassing follow-up commit.
API development is another big one. When building or consuming REST APIs, you need to verify that request and response bodies are valid JSON. A common mistake is sending JavaScript objects (with single quotes or trailing commas) instead of proper JSON.
Data pipelines are the sneaky third case — ETL jobs, webhook payloads, event streams all pass JSON between services, and when one of those payloads is malformed the pipeline either breaks silently or corrupts everything downstream. We have seen a single missing bracket in a webhook body take down an entire notification system because nobody validated at the boundary.
Someone copies a JS object into a config file and wonders why the parser chokes — we see this more than any other failure.
JSON demands double-quoted keys. Rejects trailing commas. Cannot handle undefined or NaN. Zero comment syntax. Those four rules cover ~90% of errors.
Quick fix: JSON.stringify(obj, null, 2) converts any JS object to valid JSON. The other direction is JSON.parse(jsonString).
Trailing commas: JSON does not allow a comma after the last item in an array or object. Remove the comma before the closing bracket or brace.
Single quotes: JSON requires double quotes for strings and keys. Replace all single quotes with double quotes.
Unquoted keys: { name: "Alice" } is valid JavaScript but invalid JSON. Wrap all keys in double quotes: "name": "Alice".
Comments: JSON has no comment syntax. Remove all // and /* */ comments, or switch to JSONC if your tooling supports it.
When you paste JSON containing API keys, internal endpoints, or customer data into an online tool, you want to be sure it stays on your machine. This validator uses the browser built-in JSON.parse() — no network requests, no server processing.
Press Ctrl+Enter (Cmd+Enter on Mac) to validate manually. Press Ctrl+Shift+C to copy the validation result to your clipboard. The validator also runs automatically as you type with a short delay.
Catches trailing commas, single quotes, unquoted keys, missing brackets — the stuff that breaks builds. Shows the exact line and column.
Everything runs in your browser via JSON.parse(). No server calls, no data transmitted. Check the Network tab in DevTools to verify.
Trailing commas after the last item, single quotes instead of doubles, unquoted property names, comments (JSON has zero comment syntax), and missing closing brackets.
We deliberately do not auto-fix because that can silently change meaning. The validator shows you exactly where the problem is — you decide what the fix should be. For formatting, our JSON Formatter handles that.
Validation tells you if the JSON is broken and where. Formatting takes valid JSON and makes it readable with indentation. Our JSON Formatter does both — validates first, formats if it passes.
No — zero comment syntax of any kind. If you need comments in configs, JSONC or YAML are the usual alternatives. This validator follows the strict JSON spec.
JS objects and JSON look almost identical but the rules diverge in annoying ways — JSON demands double-quoted keys, rejects trailing commas, cannot handle undefined, and has no function support. Run JSON.stringify() to convert.
Drag and drop the file onto the page. It handles files up to several megabytes since everything runs in your browser. For 100MB+ files, jq or python -m json.tool on the command line is faster.
Ctrl+Enter to validate, Ctrl+Shift+C to copy the result. Also auto-validates as you type with a short delay.
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