Comment utiliser : YAML Validator
- Paste YAML or open a
.yml/.yamlfile. - Errors show the line, column and a pointer to the exact spot.
- Review the lint warnings for tabs, trailing spaces and YAML 1.1 pitfalls.
- Copy the formatted YAML or the JSON equivalent.
Why YAML breaks so easily
YAML uses indentation for structure, so a single misplaced space changes the meaning or makes the file invalid. The most common errors:
| Error | Cause |
|---|---|
| bad indentation of a mapping entry | A key is indented differently from its siblings |
| found a tab character | YAML forbids tabs for indentation — use spaces |
| duplicated mapping key | The same key appears twice in one object; most parsers silently keep the last one |
| incomplete explicit mapping pair / unexpected end | An unclosed quote, bracket or a colon inside an unquoted string |
| end of the stream or a document separator is expected | Content at the wrong indentation after a list or block |
YAML 1.1 vs 1.2 gotchas
Many tools (PyYAML, older Ruby and Go libraries) still follow YAML 1.1, where yes, no, on, off are booleans and 012 is octal — the famous “Norway problem” where the country code NO becomes false. YAML 1.2 treats these as strings. The linter flags such values so you can quote them and get the same result everywhere.
Multi-document files
Kubernetes manifests often combine several resources separated by ---. Each document is validated and shown in the JSON output as an array.
Validating meaning, not just syntax
Valid YAML can still be a wrong configuration. For structure checks against a schema, convert to JSON and use the JSON Schema validator; for API specs, the OpenAPI validator. Build new files with the Docker Compose generator or GitHub Actions generator, and convert formats with YAML to JSON.
Aussi recherché comme : yaml lint, yaml checker, validate yaml, yaml syntax check, yamllint online, yaml formatter, kubernetes yaml validator.
Outils complémentaires : YAML Validator
- JSON to YAML — Paste JSON and get clean YAML for Kubernetes manifests, Docker Compose, GitHub Actions or any config file.
- Kubernetes YAML Generator — Fill in your app’s name, image and port and get production-ready Kubernetes YAML: a Deployment with probes, resource limits and a hardened security context, plus the Service, Ingress with TLS, ConfigMap, Secret and HorizontalPodAutoscaler you tick — in one file ready for kubectl apply.
- systemd Service Generator — Run your app as a proper Linux service that starts on boot and restarts when it crashes.
- GitLab CI Generator — Pick your stack and get a working .gitlab-ci.yml: install with caching, lint and test jobs, a build with artifacts, a Docker image pushed to the GitLab registry, or a GitLab Pages deploy — with rules that run pipelines for merge requests and your default branch without duplicates.