YAML vs XML
Comparing YAML Ain't Markup Language and Extensible Markup Language — which format should you use?
| YAML | XML | |
|---|---|---|
| Full Name | YAML Ain't Markup Language | Extensible Markup Language |
| Extension | .yml | .xml |
| MIME Type | application/x-yaml | application/xml |
| Category | data | data |
YAML Pros
- +Very human-readable
- +Supports comments (JSON doesn't)
- +Less verbose than JSON or XML
- +Widely used in DevOps (Docker, Kubernetes, GitHub Actions)
YAML Cons
- -Indentation-sensitive (tabs vs spaces cause errors)
- -Implicit typing can cause surprises ('yes' becomes boolean true)
- -Not as fast to parse as JSON
- -Complex features (anchors, aliases) are confusing
XML Pros
- +Human-readable and self-descriptive
- +Platform and language independent
- +Supports complex hierarchical data
- +Extensive tooling and validation (XSD, DTD)
XML Cons
- -Verbose — much larger than JSON or CSV
- -Slower to parse than JSON
- -Complex syntax rules
- -Being replaced by JSON in many modern use cases
Use YAML when...
- -Docker Compose files
- -Kubernetes manifests
- -GitHub Actions workflows
- -CI/CD pipeline configs
- -Ansible playbooks
Use XML when...
- -SOAP web services
- -Configuration files (Android, Maven, Spring)
- -RSS/Atom feeds
- -SVG graphics
- -Office document formats (DOCX, XLSX)