Can YAML be lossy when converted to JSON?

YAML-specific types like dates, binary and sets have no JSON equivalent. In the default mode they become ISO-8601 strings, base64 strings and objects, and the tool lists every conversion it made. In strict mode a bare date is simply a string.

What happens with multiple documents?

Multi-doc YAML streams are converted to a JSON array, one element per document, with a tab for each document so you can copy just one.

Why does a duplicate key fail?

YAML 1.2 forbids duplicate keys in a mapping, so the parser reports the line. Enable "Allow duplicate keys" if you want the last value to win instead.

YAML to JSON

Turn YAML documents into JSON. Multi-document streams are detected automatically and shown per document, anchors and merge keys are resolved, YAML-only types such as timestamps and !!binary are converted to JSON-safe strings with a note, and duplicate keys are reported with their line. Useful when a tool expects JSON but you have config in YAML.

Runs locally in your browser

For large YAML, open fullscreen for a wider view

YAML input

0 chars · 1 line

JSON output

Output will appear here…

Indent

YAML types

Sort keys alphabeticallyAllow duplicate keys (last one wins)

Multi-document streams (---) are detected automatically and output as an array, with a tab per document. "Resolve & convert" parses timestamps, !!binary, .inf and other YAML 1.1 types and converts them to JSON-safe strings or null; "Strict JSON types" only recognises the types JSON has, so a bare date stays a string. Duplicate keys are an error by default because YAML 1.2 forbids them.

JSON to YAML

Convert JSON into clean YAML with control over quoting, wrapping, anchors and multi-document output.

JSON Formatter

Beautify, minify, sort, query and repair JSON with a tree view and copy-as code export.

TOML to JSON

Convert TOML config to JSON and JSON back to TOML, with Cargo, pyproject and netlify presets.

XML to JSON

Convert XML to JSON and JSON back to XML, with attribute, text-node, namespace and array controls.

How to use YAML to JSON

1Paste or upload YAML. Errors show the line and column.
2For multi-document streams (---) use the tabs above the output to view all documents as an array or one at a time.
3Choose Resolve & convert to turn timestamps, binary and .inf into JSON-safe values, or Strict JSON types to keep them as plain strings.
4Copy or download the JSON.

About YAML to JSON

YAML to JSON is part of FizzKit — a collection of focused developer and ad-tech tools. Because everything runs locally, it works offline once loaded and never exposes your data to a remote server.

Frequently asked questions

Yes. Anchors (&), aliases (*) and merge keys (<<) are resolved during conversion.

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