JSON validator & beautifier
What this JSON validator & beautifier does
Paste JSON text and find out whether it is syntactically valid under RFC 8259 rules, then reformat it with indentation so humans can diff keys, spot duplicate fields, and align nested arrays. It catches classic mistakes: trailing commas after the last property, single quotes instead of double quotes, bare words instead of strings, and truncated chunks from copy errors.
When to use it
Use it when Postman shows a mysterious 400, when a CI fixture silently drifted, or when you need to compare two API snapshots side by side. Export sensitive payloads carefully—browser extensions can read clipboards. Pair with SQL formatter/beautifier when debugging mixed SQL+JSON logging, and with HTML entity converter when characters were double-escaped into a string field.
Worked example
A webhook body fails signature verification. Beautifying reveals an extra comma before } that your serializer tolerated locally but the remote parser rejects—fix the JSON, not the HMAC secret.
Frequently asked questions
Does it validate JSON Schema?
No—syntax only. Semantic correctness needs schema tools or contract tests.
Comments in JSON?
Standard JSON forbids them. Some configs allow JSON5 or JSONC; this strict validator will flag those.
Huge payloads?
Browsers can choke on megabyte pastes. Use streaming validators or CLI jq for big files.