Are the samples a single YAML document?

Yes. Each file is one document with a top-level mapping and a sequence of records.

What is the MIME type of a YAML file?

The MIME type is application/yaml. The file extension is .yaml.

Is a sample YAML file the same as a dummy or example YAML file?

Yes. Sample, test, dummy and example YAML files are different names for the same thing: a YAML file with known contents that stands in for a real one. Any file on this page will do wherever a tutorial or a test plan asks for a dummy YAML file.

Free YAML sample files

Human-friendly data serialisation that relies on indentation. The format of most infrastructure configuration. Download valid YAML test files in 4 exact sizes, from 1 KB to 1 MB, each with a checksum.

Extension: .yaml
MIME type: application/yaml
Kind: Text
Category: Configuration

YAML files by size

Every file below is a valid YAML Ain't Markup Language file of exactly the stated size. Open a file's page for its checksum and contents, and to preview it in your browser before downloading.

YAML sample files by size
File	Size	Contents	Download
1 KB YAML samplesample-yaml-1kb.yaml	1 KB1,024 bytes	Records: 3	Download YAML
10 KB YAML samplesample-yaml-10kb.yaml	10 KB10,240 bytes	Records: 42	Download YAML
100 KB YAML samplesample-yaml-100kb.yaml	100 KB102,400 bytes	Records: 426	Download YAML
1 MB YAML samplesample-yaml-1mb.yaml	1 MB1,048,576 bytes	Records: 4,336	Download YAML

More YAML samples

Hand-designed files with realistic content or a specific edge case.

Curated YAML sample files
File	Size	Contents	Download
Sample Docker Compose YAMLsample-docker-compose.yaml	744 B744 bytes	Features: Anchors and aliases, sequences, nested mappings, quoted strings, comments	Download YAML

What is a YAML file?

YAML expresses mappings, sequences and scalar values using indentation rather than brackets, which makes it pleasant to write by hand. Kubernetes, Docker Compose, GitHub Actions and Ansible are all configured with it.

YAML is a superset of JSON and has a great deal of syntax, including anchors for reusing values and several ways of writing multi-line strings.

How to recognise a YAML file

No signature bytes. YAML files are identified by parsing their content.

Extension	.yaml
MIME type	application/yaml
Specification	YAML 1.2.2
Extensions	.yaml and .yml
Indentation	Spaces only; tabs are not allowed
Features	Anchors, aliases, tags, multiple documents per file

What to test for

These are the behaviours that most often go wrong when software handles YAML files.

Unquoted values are typed by guesswork. In YAML 1.1 parsers the country code NO becomes false, and a version such as 1.10 becomes the number 1.1.
Loading untrusted YAML with a full loader can construct arbitrary objects in some libraries; always use the safe loader.

Strengths of YAML

Easy for people to read and write, with support for comments.
Anchors and aliases avoid repeating shared configuration.

Limitations of YAML

Significant indentation makes small mistakes change the meaning silently.
Implicit typing turns some plain values into booleans or numbers unexpectedly.

Typical uses of YAML test files

Testing configuration loaders and linters
Checking CI pipeline tooling
Testing converters between YAML and JSON

Software that opens YAML

Kubernetes, Docker Compose, Ansible, GitHub Actions
PyYAML, js-yaml, SnakeYAML and yq

Specifications

YAML sample files: questions

Are the samples a single YAML document?: Yes. Each file is one document with a top-level mapping and a sequence of records.
What is the MIME type of a YAML file?: The MIME type is application/yaml. The file extension is .yaml.
Is a sample YAML file the same as a dummy or example YAML file?: Yes. Sample, test, dummy and example YAML files are different names for the same thing: a YAML file with known contents that stands in for a real one. Any file on this page will do wherever a tutorial or a test plan asks for a dummy YAML file.