ValidateYAML

Validate YAML, layer by layer

Paste or open a file. Each layer — bytes, syntax, schema, rules — reports its own verdict, so “no schema” never looks like “passed”.

true/false only are booleans; 0o17 is octal; yes/no/on/off are strings.

411 chars · 22 lines · rev 1Not saved yet

Tab inserts two spaces (press Esc then Tab to leave the editor). Drop a file to open it. Positions are line:column in UTF-16 code units.

Paste YAML or open a file to validate

rev 1 · YAML 1.2 · core schema · no schema

  1. —

  2. —

  3. No schema selected

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Results appear here.

Why layered validation

A green tick from a YAML linter usually means only “the parser did not crash”. Whether a file is valid depends on which YAML version resolved its scalars (is no a string or false?), which schema described its structure, and which team rules apply.

ValidateYAML keeps those questions apart. Encoding problems, YAML syntax, JSON Schema violations and style or policy findings are separate layers with separate statuses: valid, warnings, invalid, incomplete, unsupported, not run or canceled.

What “valid” means here

Valid within profile means: under the YAML profile you selected, against the schema you attached, with the rules you enabled, no errors were found. Without a schema, the verdict reads “syntax checked — schema not run”.

No local tool can prove that GitHub, Docker or a Kubernetes API server will accept a file. Reports say so explicitly.

Questions

Is my YAML uploaded anywhere?

No. Parsing, schema validation, rules, fixes and reports all run in your browser (validation runs in a Web Worker). There is no backend, no account and no content analytics. Drafts and history are stored only in this browser’s IndexedDB, and you can clear them or switch to memory-only mode.

Which YAML version does the validator use?

The one you choose, shown in the toolbar: YAML 1.2 core (default), YAML 1.1, 1.2 JSON or 1.2 failsafe. The Types tab shows how every scalar resolved and flags values that would change under the other version. A %YAML directive in the file overrides the profile for that document, and we tell you when it does.

Why does it say “incomplete” instead of valid?

Because something was not fully checked: the schema used a keyword this engine does not evaluate (such as $dynamicRef) or an unknown keyword, a document could not be projected to JSON without loss, or a check hit its time budget. Incomplete results never receive a valid badge.

Does it fetch $ref schemas from the internet?

Never. A remote $ref stops the schema layer with “not run: reference unresolved” and offers to map that URI to a local schema you paste or open.