YAML to JSON Converter – Free, Online, Private

Why the reverse direction is stricter

YAML allows comments, several documents in one stream, unquoted strings, and implicit types. JSON allows none of that. This converter reads a single YAML value and serializes it with JSON.stringify. Comments disappear. A value that YAML read as a boolean stays a boolean. Dates that js-yaml turns into Date objects become ISO strings, which is the usual surprise: an unquoted 2026-10-16 can stop being a string. Quote it in the YAML if you need a string in the JSON.

Indentation and tabs

YAML indentation must be spaces. A tab used for indent is an error in the spec and this page reports it. Nested maps line up under their parent. A sequence item's content can sit on the dash line or on the next line. If you copied from a browser and the indent collapsed, the error position from the parser is the place to look. Mixed indent widths in one file are legal as long as each level is consistent, but they are a common source of "bad indentation" errors.

Multi-document streams

A file that contains two YAML documents separated by --- is not one JSON value. This converter reads the first document. Split the file if you need both. Directives such as %YAML 1.1 are ignored by the loader when they are not needed. Custom tags such as !!python/object are not executed; unsafe types are rejected rather than turned into objects. That is intentional. Do not use this page as a YAML sandbox for untrusted tags.

Worked example

The sample is one YAML map: id 42, name Ada Lovelace, active true, a tags sequence of math and engines, and an address map with city London and zip SW1A. The JSON result is one object, not a list of documents. tags becomes a JSON array of two strings. address becomes a nested object with city and zip, not a dotted key. An unquoted yes added beside active would become boolean true, which is the YAML typing trap this page is about. A comment above id disappears, because the JSON form has nowhere to put it. That is a different result from the JSON-to-YAML page, which starts from braces and never had a comment to drop.

Typical uses

Developers paste a Kubernetes manifest fragment to see the exact JSON a controller would store. Others convert an OpenAPI example written in YAML before posting it to an endpoint. Because the work stays on device, private hostnames and secrets in the file are not logged by this site. After conversion, the JSON formatter on Utilo can minify or query the result.

Frequently asked questions