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Paste any YAML — Ansible inventories, Nornir hosts files, Kubernetes manifests, CI pipelines — and get instant syntax validation with the exact line and column of any error, plus a one-click reformat to clean, consistent indentation. Runs entirely in your browser using js-yaml; nothing is sent anywhere. Checks syntax and structure, not a specific schema (it won't know if a Kubernetes field name is wrong, only if the YAML itself is malformed).
YAML Input
Result
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Result will appear here as you type…
"Format & Re-lint" re-serializes valid YAML with clean 2-space indentation (anchors/aliases are expanded to their full values in the output).
Examples (click to load)
key: valueScalar mapping
- itemList item
key:
nested: valueNested mapping (indent with spaces)
[a, b, c]Flow-style list
{a: 1, b: 2}Flow-style mapping
|Literal block scalar (keeps newlines)
>Folded block scalar (folds to spaces)
# commentComment, ignored by the parser
null / ~Null value
true / falseBoolean
TabsYAML forbids tab characters for indentation — spaces only
yes / no / on / offUnquoted, these parse as booleans (the "Norway problem")
010Leading zeros can be parsed as octal — quote it if you mean a string
key: http://xA bare colon inside a value can be misread — quote the value
Duplicate keysMost parsers silently keep the last one
Inconsistent indentSibling keys must align to exactly the same column
---Start a new document in a stream
...End the current document
&nameDefine an anchor on a value
*nameReference (alias) an anchor
<<: *nameMerge key — inherit another mapping's keys
!!str / !!intExplicit type tags