Validators
Validate JSON, YAML, XML, JavaScript and CSS syntax with detailed error reporting
All 1 validator tools run entirely in your browser. Paste your JSON, YAML or XML and get instant validation with detailed error messages including line numbers and path information — your data is never uploaded.
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About Validators
Strict, detailed validators for the most common data formats. All 1 tools provide line-number error highlighting, schema validation and format-specific checks. Everything runs in-browser — no server, no uploads, no account.
Features
- ✓JSON validator — strict RFC 8259 compliance with line-number error highlighting
- ✓YAML validator — full YAML 1.2 spec support including anchors, aliases and multi-document
- ✓XML validator — well-formedness and optional DTD/schema validation
- ✓Detailed error messages with line number, column and path information
- ✓Syntax-highlighted editor with real-time error squiggles
- ✓JSON formatter and tree view available alongside validation
- ✓Runs 100% in your browser — nothing uploaded
Common Use Cases
- Validate a JSON API response body to find the exact line causing a parse error
- Lint a Kubernetes YAML manifest or GitHub Actions workflow before committing
- Check an XML configuration file for well-formedness before deploying
- Validate a JSON config file against a known schema
- Debug a handwritten JSON file with trailing commas or missing quotes
Frequently Asked Questions
QIs my data sent to a server?
No. All validation runs entirely in your browser using JavaScript parsers. Nothing you paste is transmitted.
QWhat is the difference between JSON validation and JSON formatting?
Validation checks that your JSON is syntactically correct (parseable). Formatting additionally pretty-prints it with consistent indentation. The JSON formatter in this collection validates and formats in one step.
QDoes the YAML validator support YAML anchors and aliases?
Yes. The YAML validator uses js-yaml which fully supports YAML 1.2 including anchors (*alias), merge keys (<<: *anchor) and multi-document streams (--- separator).
QCan I validate JSON against a JSON Schema?
Use the JSON Schema Generator tool to infer a schema from sample data, then validate against it using the JSON formatter's schema validation mode.
See Also
- Validator HubJSON, YAML and XML validators with detailed error reporting
- JSON FormatterFormat, validate and explore JSON with tree and graph view
- YAML FormatterValidate and format YAML with tree view
- XML FormatterFormat and validate XML with tree view
- JSON Schema GeneratorInfer a JSON Schema from a JSON sample document
- Format ConvertersConvert between JSON, YAML, XML, CSV and more