YAML to JSON converter
Convert YAML to JSON, including anchors, merge keys and multiple documents.
What you get
- Convert YAML to JSON online, including multi-document files, anchors and merge keys.
- Checked: the JSON is compared with the parsed YAML value by value.
- Open a .yml or .yaml file: YML to JSON for docker-compose files, Kubernetes manifests, CI workflows and app config.
- Private and free: everything runs in your browser, nothing is uploaded, and there is no sign-up.
How each result is checked
- Your YAML is parsed strictly as YAML 1.2: duplicate keys and syntax errors are rejected with the line number.
- The JSON output is parsed back and compared with the parsed YAML, value by value.
What can't convert exactly
- Anchors (&), aliases (*) and merge keys (<<) are expanded into full copies, because JSON has no references.
- Comments and custom tags such as !Ref are not data, so they are not carried over. You get a warning when this happens.
- Several documents separated by --- become one JSON array.
Questions
Does it support docker-compose and CI files with << merge keys?
Yes. Merge keys are applied, so the JSON shows the final merged values.
Why is "yes" still a string?
In YAML 1.2, "yes" and "no" are strings. Only true and false are booleans.
Can I convert docker-compose or Kubernetes YAML to JSON?
Yes. Open the .yml or .yaml file or paste it: docker-compose files, Kubernetes manifests (several documents separated by --- become a JSON array) and anchors with merge keys all convert. Custom tags such as !Ref are named in the result.
How do I convert YAML to JSON online?
Paste your YAML or open a file on the left (or click Example). The JSON appears on the right as you type, already checked. Copy it, or download it as a file. Nothing is uploaded.
Can the JSON output be wrong?
Every result is checked before it is shown (the checks are listed on this page). If a check fails, the page says "Review needed" and why, instead of presenting the output as correct, and anything that cannot convert exactly is named in the notes.