What “valid” means
The syntax pass checks YAML structure under YAML 1.2 Core or JSON-compatible scalar resolution. Duplicate mapping keys, broken flow collections, invalid indentation, unknown aliases and malformed block scalars are rejected.
Validate YAML 1.2 syntax, inspect anchors and aliases, catch portability/style hazards, and optionally validate YAML data against JSON Schema — entirely in your browser.
Click a row to jump to the source line.
| Severity | Line | Code | Message |
|---|---|---|---|
| Validate to populate diagnostics. | |||
The syntax pass checks YAML structure under YAML 1.2 Core or JSON-compatible scalar resolution. Duplicate mapping keys, broken flow collections, invalid indentation, unknown aliases and malformed block scalars are rejected.
Anchors and aliases are audited without expanding the entire graph. Reusing an anchor name is accepted because YAML 1.2 resolves aliases to the most recent preceding anchor.
The validator flags YAML 1.1-style boolean words such as yes/on, leading-zero identifiers, date-like scalars, trailing whitespace and long lines so files behave more predictably across ecosystems.
After syntax validation, JSON-compatible YAML can be validated against JSON Schema Draft 2020-12, 2019-09 or Draft-07. Schema input may itself be JSON or YAML.
Alias count and nesting depth limits help prevent pathological documents from monopolizing the browser. You can raise the limits for trusted files.
No account, upload or telemetry is required. Parsing, linting, schema validation, batch processing and ZIP creation run locally.
This validator targets the YAML 1.2 constructs used by modern configuration and data files, including block/flow collections, anchors, aliases, merge keys, directives, block scalars and custom tags. Application-specific tag semantics are intentionally not executed.