JSON ↔ YAML Converter

Convert JSON into clean, readable YAML — or parse YAML back into pretty-printed JSON — with nested objects, arrays, and value types preserved, all in your browser.

JSON input

YAML output

Everything runs in your browser — your data is never uploaded to a server.

Understanding the JSON ↔ YAML Converter

The JSON ↔ YAML Converter turns JSON into clean, human-readable YAML and parses YAML back into pretty-printed JSON, right in your browser. Flip a mode toggle, paste your data, and click Convert — then copy the result or download it as data.yaml or data.json. It is built for developers wrangling Kubernetes manifests, CI pipelines, Docker Compose, and app config files who need to move between the two formats without trusting a server. Nested objects, arrays, numbers, booleans, and nulls are all preserved. Because every step runs locally in JavaScript, your data never leaves your device and nothing is uploaded.

How it works

For JSON → YAML, the tool runs JSON.parse() on your input to build a native JavaScript value, then feeds it to js-yaml's yaml.dump() with { indent: 2, lineWidth: -1 } so output uses two-space indentation and never wraps long lines. For YAML → JSON, it calls yaml.load() to parse the document into a value, then JSON.stringify(value, null, 2) to pretty-print it. Both directions preserve structure and scalar types. Errors are caught and shown inline: a JSON SyntaxError surfaces its message, a js-yaml YAMLException surfaces its reason (with line context), and empty input prompts you to paste something. No data is sent anywhere.

JSON → YAML: yaml.dump(JSON.parse(input), { indent: 2, lineWidth: -1 }) | YAML → JSON: JSON.stringify(yaml.load(input), null, 2)

Worked example

Paste {"name":"Ada","skills":["math","engineering"],"active":true} in JSON → YAML mode and click Convert. You get: name: Ada skills: - math - engineering active: true The object becomes a block mapping, the array becomes a two-item sequence, and the boolean stays a real boolean (not the string "true"). Switch to YAML → JSON, paste that YAML back, and you recover the original object as indented JSON — a clean round trip.

Tips & common mistakes

Switching modes loads a matching sample (JSON or YAML) so the tool is never blank — just overwrite it with your own data.
JSON is a strict subset of YAML 1.2, so valid JSON always converts to YAML; the reverse only works when the YAML maps cleanly to JSON value types.
Long string values stay on one line because lineWidth is set to -1 — handy for URLs, tokens, and base64 blobs that you don't want wrapped.
YAML comments (# ...) are dropped when converting to JSON, since JSON has no comment syntax — keep an original copy if comments matter.
Watch YAML indentation: mixing tabs and spaces or misaligning a nested block is the most common cause of a parse error, and the inline message points to the offending line.
Duplicate keys, anchors/aliases, and custom tags can behave unexpectedly across a round trip — verify critical config after converting.
Use Download to save data.yaml or data.json directly, or Copy to paste straight into your editor or a config file.

Frequently Asked Questions

Does it preserve nested objects and arrays?

Yes. The converter keeps your full data structure intact in both directions — nested objects become indented mappings, and arrays become YAML sequences (and vice versa). Numbers, booleans, and null values keep their types as well.

Which YAML version does it use?

It uses the js-yaml library, which targets the YAML 1.2 specification. That means JSON is a valid subset of YAML, so any value you can express in JSON round-trips cleanly to YAML and back.

Is my data uploaded anywhere?

No. All parsing and conversion happen locally in your browser using JavaScript. Your JSON and YAML never leave your device and nothing is sent to a server.