YAML Validator
This YAML validator parses a document and reports the first syntax error with its exact line and column. YAML has no brackets to close, so indentation alone carries the structure — which means an invisible character can change what the document means. The failures that come up most are a tab where spaces were expected (YAML forbids tabs for indentation outright), a missing space after a colon, and a list item indented one level away from its parent. Multi-document files separated by --- are supported, and the number of documents found is reported.
How it works
Parses the document and reports the first syntax error with its line and column. YAML is whitespace-sensitive, so the usual culprits are a tab where spaces were expected, a missing space after a colon, or a list item indented one level off.
Multi-document files separated by --- are supported, and the count of documents found is reported.
Everything runs in your browser — nothing you paste is sent to a server.
How to validate YAML
- Paste your YAML into the editor.
- A green banner confirms it parses, and reports how many documents it found.
- If it does not parse, the first error is shown with its line and column.
Why YAML errors are usually about whitespace
YAML has no brackets to close, so indentation alone carries the structure — which means an invisible character can change what the document means. The three that account for most failures are a tab where spaces were expected (YAML forbids tabs for indentation outright), a missing space after a colon, and a list item indented one level away from its parent.
Syntax, not schema
This checks that the document parses. It does not check that it contains the keys a particular tool expects — a Kubernetes manifest with a misspelled field is still perfectly valid YAML.
Multi-document files
Files that hold several documents separated by --- are supported, and the count is reported so you can
confirm the separators landed where you intended.
Frequently asked questions
How do I check whether my YAML is valid?
Paste it into the editor. A green banner confirms it parses and reports how many documents were found; otherwise the first error appears with its line and column.
Why are YAML errors so often about whitespace?
YAML has no brackets, so indentation alone carries the structure and an invisible character changes the meaning. Tabs used for indentation are forbidden outright, a colon needs a space after it, and a list item indented one level off attaches to the wrong parent.
Does it check my document against a schema?
No. It checks that the document parses as YAML. A Kubernetes manifest with a misspelled field name is still perfectly valid YAML — catching that needs a schema check against the tool that consumes it.
Are multi-document files supported?
Yes. Files holding several documents separated by --- are parsed in full, and the count is reported so you can confirm the separators landed where you meant.
Is my YAML sent anywhere?
No. Validation happens entirely in your browser.
Related tools
YAML Formatter & Beautifier
This YAML formatter normalises indentation, quoting and flow style across a whole document.
YAML Viewer
This YAML viewer renders a document as a collapsible tree so the nesting becomes obvious.
YAML to JSON Converter
This YAML to JSON converter parses YAML into JSON online, supporting anchors, aliases, and multi-document files.