JSON to YAML Converter

Direction

Source data

Result

Resultname: unitools version: 2 public: true
Output lines3
Output characters38
Input characters58

Two formats, the same data

Converts configuration between JSON and YAML in both directions, validating the source as it goes.

JSON and YAML describe the same data structures and look nothing alike. JSON is stricter and machines prefer it; YAML is more readable and is what configuration uses — Docker Compose, Kubernetes, GitHub Actions.

Converting between them comes up constantly: an API returns JSON but the config wants YAML, or documentation gives YAML that has to go somewhere only JSON is accepted.

What this calculator shows

The converted result in the direction you chose
A specific error when the source will not parse
Input and output size in lines and characters

What to keep in mind

The YAML-to-JSON direction handles nested maps, the common configuration shape, but not anchors or block scalars.
YAML indentation must be spaces — tabs are forbidden by the specification.

FAQs

Why is YAML better for configuration?

Comments, no quotes or braces, and multi-line values. JSON has no comments at all, which for a config file is a genuine problem.

Why can't YAML use tabs?

The specification forbids them to avoid ambiguous indentation. Most broken YAML files contain an accidental tab.

Is JSON a subset of YAML?

Since YAML 1.2, yes — any valid JSON is valid YAML. The reverse is false: anchors, comments and block scalars have no JSON equivalent.

What is the Norway problem?

In YAML 1.1 an unquoted no parsed as boolean false, turning Norway's country code into a boolean. YAML 1.2 fixed it.

Worked example

A small config

Input: JSON with name, version and public

Output: Three lines of YAML, no quotes or braces

Note: YAML is noticeably shorter, which is why configuration prefers it. Strings containing a colon still get quoted, or the parser would see a new key.

Useful links

All tools in Dev Tools

JSON to YAML Converter

Result

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Useful links