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YAML/JSON5 Config Validator

Validate YAML, JSON5 and JSON config files with line-numbered syntax errors, lint warnings such as tab indentation, and conversion between formats.

YAML/JSON5 Config Validator

Indent:
YAML config19 lines / 387 chars

Format comparison

YAML

  • • Human-readable, minimal syntax
  • • Comments with #
  • • No quotes needed for most strings
  • • Indentation-based structure
  • • Best for: Config files, CI/CD

JSON5

  • • JSON with comments (// and /* */)
  • • Trailing commas allowed
  • • Unquoted object keys
  • • Single or double quotes
  • • Best for: OpenClaw configs

JSON

  • • Strict, standardized format
  • • No comments
  • • All keys must be quoted
  • • No trailing commas
  • • Best for: APIs, data exchange

Related tools: YAML ↔ JSON converter • TOML editor

Updated . Provided as is. Check the output before you rely on it in production.

How to use YAML/JSON5 Config Validator

  1. 1

    Pick the format

    Select YAML, JSON5 or JSON to match the file you are checking.

  2. 2

    Paste your config

    Paste docker-compose.yml, app.json, .eslintrc, tsconfig.json or any other config file, or load the sample.

  3. 3

    Read the validation results

    Validation runs as you type and reports parse errors with line numbers.

  4. 4

    Convert or pretty print

    Convert the config between YAML, JSON5 and JSON, or pretty print it with your chosen indent.

  5. 5

    Download the result

    Download the validated config for your project.

Questions and answers

What is YAML/JSON5 Config Validator?
A config validator parses a configuration file and reports where it breaks before your app tries to load it. This tool checks YAML, JSON5 and JSON, gives syntax errors with line numbers, lints for tabs, trailing whitespace, duplicate keys and values that need quoting, and converts between the three formats.
Does YAML/JSON5 Config Validator store or send my data?
No. All processing happens entirely in your browser. Your configuration data never leaves your device — nothing is sent to any server.
What is JSON5 and why would I validate it?
JSON5 is a superset of JSON that allows comments, trailing commas, unquoted keys, and single-quoted strings. Many config files use JSON5 syntax, and this tool validates them without requiring strict JSON compliance.
For AI agents: how to call this tool

Machine-readable contract, endpoints and examples. Humans can ignore this section.

Best Path For Builders

Browser workflow

Runs instantly in the browser with private local processing and copy/export-ready output.

Browser Workflow

This tool is optimized for instant in-browser execution with local data handling. Run it here and copy/export the output directly.

/config-validator/

For automation planning, fetch the canonical contract at /api/tool/config-validator.json.