Technology
How to Format and Validate JSON
AllinOne Editorial · Published 2026-09-16 · Updated 2026-10-22
Formatting is whitespace. Validation is whether the text is legal JSON. Neither one proves the object matches a TypeScript type.
JSON is a data format with strict syntax: double quotes, no trailing commas, no comments. Pretty-printing only adds whitespace so humans can read it. Minifying strips that whitespace for smaller payloads.
Typical errors
- Trailing comma after the last property.
- Single quotes instead of double quotes.
- Undefined, functions, or a hanging comma from a JS object literal pasted as JSON.
Use the JSON Formatter to format or minify JSON, and the JSON Validator when you only need the parse error. Both run in the browser.
Secrets in a JWT or an env dump should not be pasted into a random website. These tools stay in your tab — still, avoid production tokens.
Frequently asked questions
Does the validator check my schema?+
No. It reports JSON.parse errors (missing commas, trailing commas, single quotes). Field names and types are your problem.
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