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Docker Compose Validator

Validate docker-compose.yml: syntax, services, ports, volumes, networks.

3 services2 errors1 warningFix the errors above
WARN · Obsolete version key: The "version" key is obsolete — Compose v2 ignores it. Remove it.
ERROR · Unknown network: Service "web" references network "appnet" which is not listed under top-level networks.
ERROR · Duplicate host port: Host port 8080 is bound by both "web" and "api" — the second binding fails at startup.
INFO · Default network: No top-level networks section — services share the implicit "default" network.

Validates YAML syntax, service definitions, port bindings, and references to networks/volumes/depends_on against the Compose spec. $VARIABLE interpolation, .env files, and external resources are not resolved here. Parsing runs entirely in your browser.

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Validate docker-compose.yml files for syntax and structure: service definitions, port conflicts, and dangling references to networks, volumes, and depends_on services. Catch "services must be a mapping, not a string" before your stack fails to start.

[x]Features
  • -Strict YAML parsing with line-level error messages
  • -Service name and image/build checks
  • -Duplicate host port detection across services
  • -Unknown network, volume, and depends_on references
  • -Obsolete version key warning
  • -Local-only processing with sample compose file
>Use Cases
  • >Debugging compose files that fail to start
  • >Checking for port collisions in monorepo stacks
  • >Reviewing shared compose templates
  • >Teaching compose indentation and structure

Frequently Asked Questions

>Is my compose file uploaded??
No. The YAML is parsed with the yaml library entirely in your browser.
>What does it validate??
YAML syntax, the services mapping, port bindings (including duplicate host ports), and references to networks, volumes, and depends_on services.
>Does it resolve $VARIABLE interpolation??
No. Interpolation, .env files, and external resources are not resolved here — values containing $ are skipped for validation.