YAML Validator

Single and multi-document YAML

A YAML stream can contain one document:

service:
  name: example
  enabled: true

It can also contain several documents separated by ---:

name: first
---
name: second

The validator accepts up to 100 documents in one stream. If parsing succeeds, the result states how many documents were read. If any part of the stream fails, it displays the message returned by js-yaml.

Parser behavior

The tool uses js-yaml locally with CORE_SCHEMA. Duplicate keys in the same mapping cause an error instead of silently replacing a value. Anchors, aliases, and merge keys are processed using the parser’s configured safety limits.

CORE_SCHEMA determines how supported plain scalars are constructed. The validator does not provide a YAML 1.1 switch or infer types beyond that schema. Quoting a value is the clearest way to preserve it as text when its type matters to your application.

Limits and scope

• Input may contain at most 1,000,000 characters and 100 documents.
• The tool checks YAML parsing and construction under the configured schema.
• It does not validate JSON Schema, OpenAPI, Kubernetes, Ansible, CI configuration, or other application rules.
• It does not prove that required fields exist or that values are suitable for a particular program.
• There is no file upload or server-side parser.

Successful parsing means the stream is accepted by this parser configuration. Another application can use a different YAML version, schema, tag set, or domain-specific validation and may reach a different conclusion.

Browser-local privacy

Your YAML, review draft, parser result, and document count stay in the browser. Nothing is uploaded, sent through Livewire, placed in the URL, or saved in server history. The three-step flow handles pasting, review, and results locally; Start over clears its local draft. Do not paste confidential configuration on a shared or untrusted device.