YAML to JSON Converter

How to convert YAML to JSON

1. Paste your YAML, open a .yaml or .yml file, or click Load Sample.
2. Click Convert to JSON. The JSON appears on the right, indented with two spaces.
3. Copy or download it. If the YAML has a mistake, the line turns red and the message explains what the parser expected.

How YAML maps to JSON

Anchors and merge keys

Docker Compose files, CI pipelines and Rails configs often reuse settings with anchors. This YAML:

defaults: &defaults
  adapter: postgres
  pool: 5
development:
  <<: *defaults
  database: app_dev

becomes

{
  "defaults": { "adapter": "postgres", "pool": 5 },
  "development": { "adapter": "postgres", "pool": 5, "database": "app_dev" }
}

Some online converters leave a literal "<<" key in the JSON. Here the merge is applied, so the JSON is what your application actually sees.

Values that change type

YAML guesses types from how a value looks, and the guess isn't always what you meant:

• country: no becomes false. Write country: "no" to keep the text.
• zip: 01701 is read as an octal number and becomes 961. Quote ZIP codes, phone numbers and IDs with leading zeros.
• version: 1.10 becomes the number 1.1. Quote version numbers.

If a value comes out different from what you expected, quoting it in the YAML is almost always the fix.

OpenAPI, Swagger and Kubernetes files

OpenAPI and Swagger specs are usually written in YAML, but some tools only import JSON. Paste the spec here, convert it and save the result as openapi.json. The same works for Kubernetes manifests: a file with several resources separated by --- becomes a JSON array with one object per resource.

Converting YAML to JSON in code

# Python (pip install pyyaml)
import json, yaml
with open('config.yaml') as f:
    print(json.dumps(yaml.safe_load(f), indent=2))

// Node.js (npm install js-yaml)
const yaml = require('js-yaml');
const json = JSON.stringify(yaml.load(fs.readFileSync('config.yaml', 'utf8')), null, 2);

# Command line with yq
yq -o=json config.yaml

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