YAML duplicate key checker
Find duplicate YAML mapping keys with document, line and column locations. Check nested maps without silently overwriting earlier entries.
Up to 100 documents, 50,000 parsed nodes and 64 nesting levels. Diagnostic reports omit source text and key values. No application schema is checked. Runs on your device with no configuration, repository or credential lookups. Up to 1,000,000 input characters and 4,000,000 characters per output file. Paste text to process locally. Review the supported syntax and the result before downloading. Results update as you type. Up to 1,000,000 characters.
Your result
How to use YAML duplicate key checker
- Paste the YAML configuration.
- Review each issue’s document and source location.
- Correct duplicates and rerun, then download the diagnostic report.
Useful next steps
Find duplicates in their own mapping
Paste one or more YAML documents. A repeated scalar key in the same mapping is flagged, including nested maps and scalar alias keys. The same key in separate maps is allowed. Numeric and quoted string keys remain distinct types.
Get locations without exposing configuration values
The report contains fixed issue messages and document, line and column numbers. It does not repeat keys, values or neighboring source lines. Up to 500 diagnostics are listed with a count of omitted issues.
Distinguish no duplicates from unsupported input
The checker also reports syntax errors and unresolved aliases. Collection-valued mapping keys and unknown tags are explicitly unsupported rather than receiving an all-clear. It does not verify application-specific settings or merge-key precedence.