YAML vs JSON: Which Data Format Should You Use?

Every developer eventually faces this choice: YAML or JSON? The answer depends on what you are building, who will read the file, and how it will be processed.

Both formats represent structured data, but they make very different trade-offs between human readability and machine simplicity.

Quick Comparison

When to Use JSON

JSON excels in machine-to-machine communication:

• APIs and web services — The universal data interchange format
• JavaScript applications — Native parsing with JSON.parse()
• Configuration with tooling — package.json, tsconfig.json
• Data storage — MongoDB, Elasticsearch, many databases use JSON natively

Format and validate your JSON with our JSON Formatter and JSON Validator.

When to Use YAML

YAML shines for human-edited configuration:

• Docker Compose — Service definitions in docker-compose.yml
• Kubernetes — Pod, service, and deployment manifests
• CI/CD pipelines — GitHub Actions, GitLab CI, CircleCI
• Application config — Settings files edited by humans

Edit and validate YAML with our YAML Editor and YAML Validator.

Syntax Comparison

JSON:

{
  "database": {
    "host": "localhost",
    "port": 5432,
    "credentials": {
      "username": "admin",
      "password": "secret"
    }
  }
}

YAML:

database:
  host: localhost
  port: 5432
  credentials:
    username: admin
    password: secret

The YAML version is shorter, has no quotes around simple strings, and no braces. But one wrong indentation breaks everything.

Converting Between Formats

Need to switch formats? Our YAML to JSON converter handles the conversion instantly. Going the other direction works just as easily.

Common Pitfalls

YAML Gotchas

• Indentation errors — Tabs are not allowed, only spaces
• Unexpected type coercion — yes, no, on, off become booleans
• Multiline strings — Multiple syntaxes (|, >, |-) cause confusion

JSON Gotchas

• No comments — Use JSONC or move metadata elsewhere
• Trailing commas — Invalid in strict JSON
• Verbose for config — Lots of quotes and braces for simple settings

Use our YAML Linter to catch indentation and syntax issues before deployment.

Frequently Asked Questions

Can I use YAML for APIs?

Technically yes, but JSON is the standard. YAML adds parsing complexity and ambiguity that APIs do not need.

Is YAML a superset of JSON?

YAML 1.2 is designed to be a superset of JSON, meaning valid JSON is also valid YAML. In practice, there are edge cases.

Which is faster to parse?

JSON is significantly faster to parse because its grammar is simpler. For API responses, this matters. For config files loaded once, it does not.

Related Resources

• YAML Syntax Tutorial — learn YAML from scratch
• JSON Formatting Best Practices — write better JSON
• YAML Editor — edit and validate YAML online
• JSON Formatter — format and beautify JSON