YAML Validator

Validate YAML syntax and catch the most common pitfalls — tab characters in indentation (illegal in YAML), duplicate keys at the same level, and the "Norway problem" (unquoted no becoming boolean false).

Common YAML mistakes

• Tabs in indentation. YAML requires spaces. Editors that insert tabs by default break this silently.
• The Norway problem. The country code NO for Norway becomes boolean false in YAML 1.1. Always quote 2-letter country codes.
• Version strings as floats. version: 1.10 parses as the float 1.1, not the string "1.10". Quote version numbers.
• Duplicate keys. YAML doesn't forbid them; behavior depends on the parser (most keep the last). Always flag as an error.
• Trailing colons. A key with no value followed by a colon and nothing else creates a null value. Easy to mistake for incomplete YAML.