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YAML Formatter & Validator

Format and validate single or multi-document YAML, convert it to JSON, or generate configurable YAML from valid JSON.

Multi-documentPrivate in browserSchema aware

YAML input

0 characters

Formatted YAML

Generated with explicit parser and serialization settings
Your processed YAML or JSON will appear here.
0 documents0 valuesDepth 00 bytes
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Multi-document streams

YAML can contain multiple documents separated by ---. JSON has no direct stream equivalent, so YAML-to-JSON returns an array when several documents are present.

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Implicit data types

Schema choice affects whether values become strings, numbers, booleans, nulls or dates. Quote identifiers and ambiguous values when their exact text must be preserved.

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Local processing

Formatting and conversion happen in the browser using a safe YAML parser. Files and pasted configuration are not uploaded by this tool.

Use YAML safely and predictably

YAML is designed for human-readable configuration, but indentation, schemas, anchors and implicit types can produce surprising results. Validate the output with the exact application that will consume it, especially for deployment and infrastructure configuration.

Why did a value change type?

Unquoted scalars can be resolved according to the selected YAML schema. Quote values such as identifiers, version numbers, timestamps and strings resembling booleans when textual preservation matters.

Are comments preserved after formatting?

No. This formatter parses YAML into data and serializes it again, so comments, original anchors, quote style and exact key layout are not preserved. Do not use it when those source-level details must remain intact.

What happens to anchors and aliases?

The serializer may generate anchors for repeated object references. Enable “Expand aliases” to duplicate those structures instead. Parsing resolves existing aliases into data.

Is converting YAML to JSON always lossless?

No. Comments, tags, anchors, aliases, mapping key types, dates, undefined values and multiple documents do not always have direct JSON equivalents. The tool reports unsupported JSON values when detected.