Tool UI
JSON Tool
JSON Validator
Use this page to check whether a JSON payload is valid before sending it to an API, saving it into a config file, or pasting it into a development workflow.
This online JSON validator is useful for catching syntax mistakes early, especially when JSON has been copied from logs, documentation, browser tools, or hand-written test data.
About the JSON validator
This page checks whether pasted JSON follows proper syntax rules. It is intended for developers, analysts, and technical users who need a fast way to verify that a payload can be parsed correctly.
It is useful for validating request bodies, exported data, fixtures, config snippets, and any copied JSON that might contain small syntax mistakes.
How to validate JSON
- Paste the JSON payload into the input area.
- Select Validate JSON to parse the payload.
- Review the status message to confirm whether the JSON is valid or malformed.
- Fix syntax problems, then validate again before using the payload elsewhere.
JSON validation is especially helpful before POST requests, config updates, test fixture generation, and any workflow that depends on strict machine-readable syntax.
What is JSON validation?
JSON validation is the process of checking whether a JSON document follows the rules required by the JSON format. A valid payload must have proper brackets, quoted keys, correctly separated values, and legal string, number, boolean, and null syntax.
Validation helps catch errors before the JSON reaches an API, parser, database, or downstream application.
Why validate JSON?
Even a tiny mistake like a missing quote or extra comma can break an API request or configuration file. Validating JSON early saves time by surfacing syntax issues before they become larger debugging problems.
It is especially useful when payloads are assembled manually, copied from documentation, or transformed by multiple tools.
JSON validator FAQ
What makes JSON invalid?
Invalid JSON usually comes from trailing commas, unquoted keys, single-quoted strings, comments, stray characters, or missing closing braces and brackets.
Is JSON the same as a JavaScript object literal?
No. JavaScript object literals allow some patterns that JSON does not. JSON requires double-quoted keys and strings and does not allow comments or undefined values.
Can I validate large API payloads here?
Yes, as long as your browser handles the pasted content comfortably. This page is meant for quick developer validation rather than backend schema enforcement.
Do I need formatting after validation?
Often yes. After you confirm the payload is valid, the JSON formatter page can make it easier to read, review, and share with teammates.
Common JSON validation mistakes
- Using single quotes instead of double quotes.
- Leaving trailing commas in arrays or objects.
- Writing unquoted object keys.
- Adding comments, which standard JSON does not allow.