.yaml — YAML Ain't Markup Language
Data application/yaml
What a .yaml file is
A human-friendly configuration format using indentation instead of brackets. Used by Kubernetes, GitHub Actions, Docker Compose and most modern CI systems.
How to open it
Any text editor, ideally one with a YAML linter.
Worth knowing
Indentation is significant and tabs are forbidden. The "Norway problem" — unquoted NO parsing as boolean false — bites everyone once.
How to identify a .yaml file
A file's extension is only its name — renaming a.png to a.yaml changes nothing inside. What software actually reads is the magic number, the first few bytes of the file.
| Signature | none |
| MIME type | application/yaml |
| Category | Data |
Plain text. May start with --- but need not.
# what is this file really?
file mystery.yaml
# look at the first bytes yourself
xxd mystery.yaml | head -2
head -c 16 mystery.yaml | xxd
# Windows PowerShell
Get-Content mystery.yaml -AsByteStream -TotalCount 16 | Format-HexFrequently asked questions
What is a .yaml file?
A human-friendly configuration format using indentation instead of brackets. Used by Kubernetes, GitHub Actions, Docker Compose and most modern CI systems.
How do I open a .yaml file?
Any text editor, ideally one with a YAML linter.
Is .yaml safe to open?
Yes. A .yaml file is data, not code — opening one cannot execute anything by itself.
Can I change a file's extension to convert it?
No. Renaming changes the label, not the bytes. The one place it appears to work is between formats that genuinely share a container — renaming .docx to .zip works because a DOCX is a ZIP. Everything else needs a real converter.
Other data formats
- .csv — Comma-Separated Values
- .json — JavaScript Object Notation
- .sql — SQL Script
- .parquet — Apache Parquet