How to use the JSON Validator
- Paste your JSON — it is validated as you type.
- If there is an error, jump to the reported line and column and read the explanation.
- Valid JSON is formatted; switch to Minify or sort keys if you need to.
The most common JSON errors
- Trailing comma —
{"a": 1,}is valid JavaScript but not JSON. - Single quotes — JSON strings and keys need double quotes:
"name", not'name'. - Unquoted keys —
{name: "x"}must be{"name": "x"}. - Missing comma between two values or properties.
- Comments —
// …and/* … */are not allowed in JSON. - Special values —
NaN,Infinityandundefineddon’t exist in JSON.
Strict validation
The validator follows RFC 8259, the same rules as JSON.parse() in browsers and every standard JSON library. If it validates here, it will parse in JavaScript, Python, Java, Go and PHP.
Validating against a schema
Syntax validation checks that the text is JSON. To check that it has the right structure — required fields, types, allowed values — use the JSON Schema Validator.
Tools that pair well with the JSON Validator
- JSON Viewer — Explore big or deeply nested JSON comfortably: fold and unfold objects, search for keys or values and click any node to get its JSONPath.
- JSON Diff — Find exactly what changed between two JSON documents — API responses, config versions, fixtures or exports — as a list of paths with old and new values.
- YAML Validator — Paste a Docker Compose file, Kubernetes manifest, GitHub Actions workflow or any YAML to pinpoint errors, catch common pitfalls and get a cleanly formatted version.
- JSONPath Tester — Type a JSONPath query and instantly see what it selects — with the exact path of each match.
Frequently asked questions
Why is my JSON invalid?
Most often because of a trailing comma, single quotes, an unquoted key or a missing comma. The error message points to the line and column where parsing failed.
Does JSON allow comments?
No. Standard JSON has no comments. Some tools accept JSONC or JSON5, but APIs and JSON.parse() do not.
What is the difference between a JSON validator and JSON Schema validation?
A validator checks syntax. JSON Schema validation checks that valid JSON also has the expected structure and types.
Can I install JSON Validator as a web app and use it offline?
Yes. JSON Validator is an installable web app (PWA) — installed from your browser, not downloaded from an app store. Click Install app at the top of this page in Chrome or Edge (Windows, macOS, Linux, ChromeOS) or on Android, use Share → Add to Home Screen on iPhone and iPad, or File → Add to Dock in Safari 17+ on a Mac. It then opens in its own window with its own icon, and because it runs entirely in your browser it keeps working offline. Firefox on desktop can’t install web apps. How installing works.