YAML vs JSON for Configuration Files — Which Should You Use?

The short answer

YAML for config files read and written by humans. JSON for data exchanged between programs.

What makes YAML good for config

YAML uses indentation instead of braces and brackets — significantly more readable for complex nested structures. Most importantly, YAML supports comments. JSON does not. For configuration files engineers edit manually, in-line explanations are invaluable.

YAML's weakness: indentation sensitivity

One wrong space breaks the entire file. Always use a YAML formatter or linter. Validate before deploying.

Common YAML gotchas

Yes, No, True, False are booleans — quote them if you mean strings. Colons followed by spaces start new mappings — quote URLs like https://example.com. Multiline strings use the pipe or greater-than syntax.

Which tools use which format

YAML: Docker Compose, Kubernetes, GitHub Actions, Ansible, ESLint (yaml version). JSON: npm, TypeScript, VS Code settings, REST APIs. Many tools accept both.

Converting between formats

Use YAML to JSON converter for migrating configs between formats. Use YAML Formatter to validate and reformat YAML before deployment.

FAQ

Is YAML faster to parse than JSON? No. JSON is faster. YAML parsers are more complex. For performance-critical data exchange, use JSON.

What YAML version should I use? YAML 1.2 fixed many surprising behaviours from YAML 1.1. Most modern tools default to 1.2.