YAML Formatter

About YAML formatting

What exactly does Format do?

It parses the input as YAML (JSON is also valid YAML, so pasting JSON works too) and re-serializes it as clean, consistently-indented block-style YAML. Line wrapping is disabled, so long strings and URLs aren't unexpectedly reflowed onto multiple lines.

Does this handle anchors and aliases (&name / *name)?

Yes — parsing and re-serializing both go through js-yaml, which resolves aliases into shared references when reading and re-emits anchors for any repeated structure when formatting back to YAML. The original anchor names aren't preserved (they're regenerated). One related feature isn't handled specially, though: a << merge key (used to blend a referenced mapping's keys into another mapping) is kept as a literal << key pointing at the referenced data, rather than being flattened into its sibling keys.

Does this support multiple YAML documents separated by ---?

No, only a single document at a time. Split a multi-document file at its --- separators and run each part through separately.

Which values does this treat as booleans?

Only true/false (and case variants like True or FALSE) parse as booleans. Unlike some older YAML tools, yes/no/on/off are kept as plain strings rather than coerced to booleans — but if a value like that appears unquoted in your input, formatting will still add quotes around it in the output, since an unquoted yes or no is ambiguous to some YAML readers.

Does this tool upload my data anywhere?

No. Parsing and formatting happen entirely in your browser via the bundled js-yaml library — no network calls. Nothing you paste ever leaves your device.