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JSON Validator

Check JSON syntax instantly, see exact parse errors, and keep everything local to your browser.

Results

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Status
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Details
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How to use this validator

  1. Paste or type your JSON in the field.
  2. Hit validate to parse it locally and surface any syntax error.
  3. If invalid, fix the highlighted issue (often the token before the reported position) and re-validate.

Rules & checks

Uses the native JSON.parse engine to enforce strict JSON syntax (no comments or trailing commas).

Surfaces the thrown error so you know the unexpected token and approximate position.

Best for payloads under ~200 KB to keep the browser responsive; larger files still run locally.

Stays fully client-side/offline—no data leaves your browser.

Inputs explained

  • JSON payload

    Paste any UTF-8 JSON string. Avoid comments/trailing commas; keep under a few hundred KB for speed.

When to use it

  • Debug API payloads before sending requests or committing fixtures
  • Validate CI/CD config snippets (env files, app settings, CMS exports) quickly
  • Check webhook samples from third parties for malformed JSON
  • Pre-flight JSON before feeding it to schema validators or transformers

Common errors

  • Trailing commas after the last item in objects/arrays
  • Single quotes instead of double quotes around keys/strings
  • Unescaped control characters or backslashes inside strings
  • Missing commas between properties
  • Forgetting to wrap property names in quotes

Limitations

  • Syntax-only: does not validate against JSON Schema or business rules.
  • Strict JSON only—no comments, trailing commas, or JSON5 extras.
  • Very large payloads may be slow; keep under a few hundred KB in-browser.
  • Does not fetch remote URLs; paste content directly.

Tips

  • Prettify first if the error position is hard to spot; then validate again.
  • Keep payloads small in the browser; chunk or stream very large files instead.
  • If you see an unexpected token, look just before the position for a missing comma or quote.
  • Avoid JSON5 features (comments, trailing commas, single quotes); this validator enforces strict JSON.

Examples

Valid: nested object with array

  • {"name":"Ada","languages":["JS","Python"],"active":true} -> Valid JSON

Valid: numbers and nulls

  • {"id":101,"meta":{"count":3,"deleted":null}} -> Valid JSON

Invalid: trailing comma

  • {"name":"Ada",} -> Invalid (unexpected token } after trailing comma)

Invalid: single quotes

  • {'name':'Ada'} -> Invalid (JSON requires double quotes for keys/strings)

Deep dive

This JSON validator runs JSON.parse in your browser to enforce strict RFC 8259 syntax and return clear error messages so you can fix malformed payloads quickly.

Use it to debug API requests, CI config, or webhook samples without uploading data. For schema validation, pair it with a JSON Schema validator after the syntax check passes.

FAQs

Is my JSON uploaded or stored?
No. Validation happens entirely in your browser; nothing is sent or persisted.
Do you support comments or trailing commas?
No. This enforces strict JSON via JSON.parse. Remove comments and trailing commas first.
How can I find the error location?
The error shows the unexpected token and a position. Prettify the JSON and check just before that position for a missing comma or quote.
Do you check against a schema?
This tool is syntax-only. After it passes, run a JSON Schema validator if you need field-level validation.
How big of a payload can I validate?
Keep it under a few hundred KB for snappy results. Very large files may be slow in the browser.
Can I use this offline?
Yes. It runs locally and continues to work offline once the page is loaded.

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