FILE FORMAT GUIDE
YAML File: What It Is & How to Open It
YAML stores mappings, sequences and scalar values in readable text. It is often used for configuration, but it is a serialization language rather than a configuration application. A .yml filename is another extension for YAML. Inspect the syntax and the consuming application's expected data model before changing values.
Quick facts
- Extension
- .yaml, .yml
- Format
- YAML
- Category
- data
- MIME type
- application/yaml
- Standard / developer
- YAML Language Development Team
- Open with
- Visual Studio Code or another text editor
What is YAML?
Block-style YAML uses indentation to express structure; flow styles use explicit punctuation. Tags and scalar resolution affect the resulting types. A YAML stream may contain multiple documents. Matching a parser's accepted syntax does not prove that the application accepts the same schema or YAML language version.
How to open YAML
Visual Studio Code or another text editorWindows / macOS / Linux
Open the YAML file as plain text. Use syntax highlighting and validation for readability, but confirm the target application's required schema before saving changes.
Common uses and compatibility
- Store configuration and serialized application data
- Exchange single-document or multi-document YAML streams
Things to check
- A single-document consumer must not silently ignore extra stream documents.
- General-purpose loading can construct objects; safe_load is the documented restricted loading interface in PyYAML.
Advanced inspection
These developer and command-line workflows inspect structure or metadata. They are not the default way most people open the file.
PyYAMLPython library
For programmatic reading, pass a text or file stream to yaml.safe_load. Use safe_load_all if multiple documents are expected. Do not use the unrestricted loader for untrusted input. This workflow reads data into Python objects; it does not launch the configured application.
Technical details
- Signature
- No registered magic number
- Encoding
- UTF-8 / UTF-16 / UTF-32 input (YAML 1.2); UTF-8 recommended for output
- Container
- Not reviewed
- Compression
- Not reviewed
Related formats
- JavaScript Object Notation
Shares structured mappings, sequences and scalar values but has a different presentation and parser ecosystem.
- TOML
Another configuration syntax, using explicit table headers instead of indentation-based nesting.
- Extensible Markup Language
An alternative serialization model based on markup elements and attributes.
Sources & review
Sources reviewed 2026-09-18.