Convert between JSON and YAML

This tool turns a YAML document into JSON and vice versa, preserving the data structure (objects, arrays, scalar types). JSON to YAML conversion, or YAML to JSON, is a common operation in development: you generate an OpenAPI YAML file from a JSON spec, you convert the output of a REST API to YAML to commit it to a configuration repository, you translate a Kubernetes YAML manifest to JSON to pass to kubectl --dry-run=client -o json, or you align a GitHub Actions workflow with a JSON schema. More broadly, it is the bridge between the data interchange world (JSON) and that of hand-editable configuration (YAML).

JSON and YAML address similar needs but different use cases. The following table summarises the main technical differences, useful to choose between the two depending on the context.

JSON is the obvious choice as soon as one program talks to another. Its typical use cases:

• REST and GraphQL APIs: request and response payloads.
• Data exchange between microservices and message queues.
• Native JavaScript code: JSON.parse and JSON.stringify without dependency.
• Browser-side storage: localStorage, sessionStorage, IndexedDB.
• AJAX and fetch requests.
• Binary or stream-oriented variants: BSON (MongoDB), JSON Lines (logs, ML datasets), MessagePack.
• Configuration of JS / TS tooling: package.json, tsconfig.json, composer.json.

YAML is the obvious choice as soon as a human regularly edits the file. Its typical use cases:

• Docker Compose (docker-compose.yml) and stack profiles.
• Kubernetes manifests (Deployment, Service, Ingress, Helm charts).
• Ansible playbooks and inventories.
• CI/CD pipelines: GitHub Actions, GitLab CI, CircleCI, Bitbucket Pipelines.
• OpenAPI / Swagger and AsyncAPI specifications.
• Annotated application configuration (Symfony, Spring Boot, Rails) where comments are useful.
• Files edited frequently by hand, where conciseness and readability matter more than parsing speed.

YAML is more permissive than JSON, which makes it a powerful but treacherous format. The most frequent pitfalls:

• Indentation: tabs are forbidden by the specification, only spaces are valid. Mixing the two or changing the number of spaces within the same block breaks parsing.
• Automatic scalar coercion: yes, no, on, off, true, false, null, None, ~ are parsed as booleans or null. Tricky example: an unquoted postal code 01234 becomes the integer 1234, and a country name NO (Norway) becomes false. Always quote ambiguous strings.
• Multi-line strings: | (block literal) keeps line breaks as is, whereas > (folded) replaces line breaks with spaces. The chomping indicators - and + adjust the behaviour on the final break.
• YAML 1.1 vs 1.2: 1.1 (still very widespread, for example via PyYAML by default) treats yes/no/on/off as booleans, which 1.2 removed. Behaviours also differ on base 8 numbers.
• Implicit dates: 2024-01-15 without quotes is interpreted as a date object by some parsers, not as a string.

The same document, expressed in JSON then in YAML. Simple configuration of an application with its dependencies and environment:

JSON version

{
    "name": "cdrn-app",
    "version": "1.14.2",
    "environment": "production",
    "dependencies": {
        "php": "^8.3",
        "symfony/framework-bundle": "^7.0",
        "doctrine/orm": "^3.0"
    },
    "features": ["cache", "mailer", "queue"],
    "debug": false
}

Equivalent YAML version

# Application configuration
name: cdrn-app
version: 1.14.2
environment: production
dependencies:
    php: '^8.3'
    symfony/framework-bundle: '^7.0'
    doctrine/orm: '^3.0'
features:
    - cache
    - mailer
    - queue
debug: false

The YAML version is about 25% shorter in characters, accepts a comment at the top and reads like a list of properties without syntactic noise.

Steps to convert your data:

1. Paste your source document (JSON or YAML) into the input field.
2. Pick the desired conversion direction (JSON to YAML, or YAML to JSON).
3. Click the conversion button: the formatted result appears in the output area.
4. Check the rendering, then use the copy button to get the result onto your clipboard.

The conversion is performed locally in your browser or via a dedicated server route depending on the tooling: no sensitive data is kept.