YAML Syntax Checker

YAML's biggest gotcha is indentation: the format uses whitespace as structure, so a misaligned line can change the meaning of your configuration or break it entirely. This tool checks your YAML for inconsistent indentation and reports problems by line number.

It is a lightweight syntax checker focused on the error that trips people up most. If no indentation problems are found, the tool reports the YAML as valid.

Worth being precise about scope: this is a structural check, not a full YAML parser. It catches the common indentation problems reliably; for deep validation, use a dedicated YAML linter in your editor.

The tool examines each line's leading whitespace and compares the indentation levels across the document. Lines that sit at an inconsistent depth — the pattern that typically indicates a missing or extra space — are flagged with their line numbers.

The analysis is a local scan of the text you paste: no request is made to any server, and nothing is retained after you close the tab.

The output lists any flagged lines with a short explanation, or confirms that no problems were detected.

YAML is a data-serialization format that uses indentation instead of brackets to show structure. Nested items are indented deeper than their parents, and the level of indentation must be consistent — mixing spaces of different widths between sibling keys is a classic error.

This tool performs a whitespace-level scan: it measures the indentation of each line and flags lines that break the document's indentation pattern. That catches the failure mode responsible for most YAML breakage.

Two caveats. First, the check is structural — it does not validate keys, types, or values, and it is not a substitute for a full parser. Second, tabs are invalid as YAML indentation in most parsers, so a line indented with a tab is a real error this tool will flag.