Convert YAML to YML

Why Convert YAML to YML?

Converting YAML to YML is a file extension change from the official .yaml to the shortened .yml extension. While both extensions represent exactly the same YAML format with identical syntax and capabilities, many tools and frameworks specifically expect the .yml extension. Docker Compose looks for docker-compose.yml by default, Ruby on Rails uses database.yml and secrets.yml, Travis CI requires .travis.yml, and Jekyll expects _config.yml.

This conversion is important for project consistency and toolchain compatibility. If your project or team uses .yml as the standard extension, converting existing .yaml files ensures a uniform codebase. Some CI/CD systems, deployment scripts, and framework conventions are hardcoded to look for .yml files, meaning the wrong extension can cause build failures or configuration loading errors.

Our converter handles this extension change cleanly, preserving the original YAML content byte-for-byte. No data is modified, no formatting is changed, and no structure is altered. The only difference in the output is the file extension, ensuring perfect round-trip compatibility. You can convert .yml back to .yaml at any time without any data loss.

Key Benefits of Converting YAML to YML:

• Docker Compatibility: Use .yml files expected by Docker Compose
• Rails Convention: Match Ruby on Rails' expected .yml configuration files
• CI/CD Compliance: Meet Travis CI and AppVeyor .yml requirements
• Project Consistency: Standardize file extensions across your codebase
• Lossless Conversion: Content is preserved exactly -- only the extension changes
• Shorter Extension: Three-letter extension for cleaner file listings

Practical Examples

Example 1: Docker Compose Configuration

Input YAML file (docker-compose.yaml):

version: "3.8"
services:
  web:
    image: nginx:latest
    ports:
      - "80:80"
  api:
    build: ./api
    ports:
      - "3000:3000"
    environment:
      - NODE_ENV=production

Output YML file (docker-compose.yml):

version: "3.8"
services:
  web:
    image: nginx:latest
    ports:
      - "80:80"
  api:
    build: ./api
    ports:
      - "3000:3000"
    environment:
      - NODE_ENV=production

Example 2: Rails Database Configuration

Input YAML file (database.yaml):

default: &default
  adapter: postgresql
  encoding: unicode
  pool: 5

development:
  <<: *default
  database: myapp_development

production:
  <<: *default
  database: myapp_production
  username: deploy
  password: <%= ENV['DATABASE_PASSWORD'] %>

Output YML file (database.yml):

default: &default
  adapter: postgresql
  encoding: unicode
  pool: 5

development:
  <<: *default
  database: myapp_development

production:
  <<: *default
  database: myapp_production
  username: deploy
  password: <%= ENV['DATABASE_PASSWORD'] %>

Example 3: CI/CD Pipeline

Input YAML file (travis.yaml):

language: python
python:
  - "3.10"
  - "3.11"
install:
  - pip install -r requirements.txt
script:
  - pytest --cov=myapp
after_success:
  - coveralls

Output YML file (.travis.yml):

language: python
python:
  - "3.10"
  - "3.11"
install:
  - pip install -r requirements.txt
script:
  - pytest --cov=myapp
after_success:
  - coveralls

Frequently Asked Questions (FAQ)

Q: What is the difference between .yaml and .yml?

A: There is no difference in content, syntax, or capabilities. Both .yaml and .yml files contain the same YAML format data. The only difference is the file extension. The .yaml extension is officially recommended by the YAML specification (yaml.org), while .yml is a shorter alternative widely adopted by tools like Docker Compose, Ruby on Rails, and Travis CI.

Q: Which extension should I use -- .yaml or .yml?

A: Use whichever extension your tools and team conventions require. If you use Docker Compose, Rails, or Travis CI, use .yml since those tools expect it. If you use Kubernetes, Ansible, or follow the official YAML specification, use .yaml. The most important thing is consistency within your project.

Q: Is any data changed during conversion?

A: No. The conversion is purely a file extension rename. The file content remains byte-for-byte identical. No data, formatting, comments, or structure is modified. You can convert back from .yml to .yaml at any time without any data loss.

Q: Why does Docker Compose use .yml instead of .yaml?

A: Docker Compose adopted the .yml extension early in its development, before the YAML community settled on .yaml as the recommended extension. By default, Docker Compose looks for docker-compose.yml (or compose.yml in newer versions). You can override this with the -f flag, but the default expects .yml.

Q: Do all YAML parsers handle both extensions?

A: Yes. All YAML parsing libraries (PyYAML, js-yaml, go-yaml, etc.) parse the file content regardless of extension. The extension is only relevant to tools that search for configuration files by name, such as Docker Compose looking for docker-compose.yml.

Q: Will my IDE recognize .yml files as YAML?

A: Yes. All major IDEs and text editors (VS Code, IntelliJ, Sublime Text, Atom, Vim) recognize both .yaml and .yml extensions and apply YAML syntax highlighting, validation, and autocompletion to both.

Q: Can I batch convert multiple .yaml files to .yml?

A: Yes. Our converter supports uploading multiple files at once. Simply select or drag all your .yaml files and they will all be converted to .yml with the content preserved exactly as-is.