.yaml file format
View, inspect, merge, and learn how YAML files are used for configuration, workflows, automation, structured data, and development projects.
Also known as: .yml
Format
.yaml
Original files stay unchanged. Tools download a new file when output is generated.
Every tool listed here works with .yaml files and runs in your browser. If the task you need is not here, the related formats below may cover it.
YAML uses indentation to express structure, so whitespace is not cosmetic. Tab characters are forbidden for indentation entirely — a single tab that a text editor inserted invisibly is one of the most common causes of a YAML file that will not load.
Unquoted scalars get type-guessed, and the guesses surprise people. In older YAML versions, values like yes, no, on, and off become booleans — which is how the country code NO becomes false, a bug well known enough to have a nickname. Leading zeros can be read as octal, and version strings like 1.10 become the number 1.1. Quote anything whose type matters.
A YAML stream can hold multiple documents separated by a line containing three hyphens. Kubernetes manifests and CI pipelines use this constantly. It is also what makes merging YAML safe: joining files as a multi-document stream keeps each one intact rather than trying to combine their keys.
Any valid JSON is valid YAML, which means you can paste a JSON block into a YAML file and it will parse. Useful when a generated fragment is easier to emit as JSON than to indent correctly by hand.
Check for tab characters used as indentation, inconsistent indentation depth between sibling keys, a missing space after a colon, or an unquoted string containing a colon or hash.
Quote anything that could be mistaken for another type: yes/no, true/false, numbers with leading zeros, version strings, and anything containing a colon, hash, or leading special character.
Nothing — both are the same format. The specification recommends .yaml; .yml is a widespread convention that some tools expect.
Files are joined into one multi-document stream separated by document markers, so each document stays intact and keys from different files cannot collide.