Validate YAML syntax, convert YAML to JSON or JSON to YAML — all client-side.
Your YAML syntax is correct.
The YAML Validator checks whether your YAML is well-formed and, when it is, converts it into equivalent JSON so you can inspect the parsed structure. Paste in a Kubernetes manifest, a docker-compose.yml, a GitHub Actions workflow, an Ansible playbook, or any .yaml config, and the tool reports syntax errors with a line reference or shows you the clean JSON tree that the parser produced.
It is built for DevOps engineers, backend developers, and anyone who edits configuration by hand, where a stray tab, a bad indent, or an unquoted colon breaks a deploy. Everything runs in your browser, so you can validate sensitive config without sending it to a server.
YAML (YAML Ain't Markup Language) is a superset of JSON, so any valid YAML document maps onto a JSON data model of scalars, sequences, and mappings. The validator parses your text against the YAML 1.2 spec, building that in-memory tree; if a token cannot be resolved into a valid node, parsing halts and the position is reported. Because JSON is a strict subset, the tool can then serialize the same tree as JSON for you to review.
Most real-world errors come from YAML's reliance on significant whitespace. Indentation must use spaces, never tabs, and sibling keys must align at the same column. A line like 'time: 12:30' is often misread because the unquoted colon is ambiguous, so it should be written as time: "12:30". Values such as yes, no, on, off, and null are interpreted as booleans or null unless quoted, which surprises people expecting literal strings.
The tool also surfaces structural mistakes that parse successfully but are rarely intended, such as duplicate keys in the same mapping (where the last value silently wins) and mixing a block sequence with a mapping at the same level. Reviewing the JSON output is the fastest way to catch these, since the JSON tree shows exactly which keys and types the parser kept.
Yes, it is completely free with no sign-up. Validation and conversion run entirely in your browser using client-side JavaScript, so your YAML is never uploaded to a server, which makes it safe for secrets and internal config.
It follows the YAML 1.2 specification, which is the version used by most modern tooling. Because JSON is valid YAML 1.2, you can also paste JSON in and it will validate.
YAML forbids tab characters for indentation; only spaces are allowed. Replace any leading tabs with spaces (two is the common convention) and the document will parse.
The parser resolves unquoted scalars to their natural types, so 007 may become 7, and true, yes, or off become booleans. Wrap the value in single or double quotes to force it to stay a string.
Yes. Files that separate documents with --- are parsed as a document stream, and the JSON output represents each document so you can confirm every section is well-formed.
It confirms the YAML syntax is valid, not that the schema is. The tool checks that the document parses; it does not verify that fields like apiVersion or required Compose keys match a specific application's schema.
Copy the JSON output directly from the tool. For the reverse direction or for reformatting large payloads, pair it with the JSON Formatter tool.