YAML to JSON Converter

What does this converter do?

It converts YAML to JSON and back, and then does the part every other converter skips: it tells you what the conversion changed and what it threw away.

• Both YAML versions, side by side. Read your file as 1.2 or 1.1 and see every value the two disagree about, with the path to each one.
• The Norway problem, named and located. Not a warning in general: the actual lines in your file.
• Merge keys. It tells you whether your << actually merged, which depends entirely on the version.
• What JSON cannot hold: comments, anchors, multiple documents, NaN and Infinity. Counted before you convert.
• Duplicate keys refused, with the line, instead of silently keeping the last one.
• Both directions on one page, because two pages for one job is duplicate content.
• Copy or download, keeping your filename: deploy.yaml becomes deploy.json.
• Nothing leaves your browser. Infrastructure YAML carries host names, bucket names and sometimes credentials.

The trap that has no good answer

Take an ordinary docker-compose file with a merge key, a timezone and a retry count. Here is the same file read both ways:

Read it one way and the merge works but three values are wrong. Read it the other way and the values are right but the merge is gone. Neither version gives you what the file looks like it says. That is not a flaw in this page, it is the actual state of YAML, and it is why the fix is always the same: quote the values you mean as text.

Docker Compose, Ansible and PyYAML are YAML 1.1. Most newer parsers are 1.2.

What else disappears

The NaN one is worth singling out. YAML can express it, JSON cannot, and JSON.stringify writes null without complaining. No parser reports an error, no linter flags it, and the value is simply gone.

What this tool does not do

• It does not preserve comments in a round trip. JSON has no comments, so once converted they are gone. No converter can do this, and any that claims to is keeping them somewhere outside the JSON.
• It does not validate against a schema. It will not tell you whether Kubernetes or your CI will accept the file, only what it means.
• It is not a YAML linter or formatter. It converts and diagnoses types.
• The comment and anchor counts are a text scan, not a full parse. They are there to warn you, not to be exhaustive.
• One parser, two schemas. Your own parser may differ again, which is exactly why both readings are shown rather than one answer.

Is my file private?

Yes. The parser is a JavaScript library that loads into your browser, and every conversion and check runs there. No network request carries your file, nothing is logged or stored, and closing the tab clears it. This is not a small detail for this particular format: a docker-compose or Kubernetes manifest usually names your hosts, your buckets and your internal services, and sometimes carries a secret that should not have been in the file at all.