# yaml.validate

```python
yaml.validate(content)
```

Parses every document in a YAML string and returns `None` on success. Invalid
syntax fails the call with the parser diagnostic, including errors after the first
document. Empty input is valid.

Custom tags are accepted as syntax and never executed. This does not resolve Atmos
functions, apply schemas, reject duplicate mapping keys, or require scalar keys.

```python
yaml.validate("first: !custom value\n---\nsecond: !env NAME\n")
yaml.validate(fs.read_file("stacks/catalog/example.yaml"))
```

Use [`fs.read_file`](/functions/automation/fs.read_file) to read files and
[`steps.test`](/steps/type/test) to report multiple independent validation failures.

Use [`yaml.decode`](/functions/automation/yaml.decode) when you need the values
from a single document instead of syntax validation.