What is YAML? A Developer's Guide to YAML vs YML

YAML is a human-readable data serialization format used widely in configuration files, APIs, and automation workflows. But what exactly is YAML, and is there a difference between .yaml and .yml? Learn more about YAML vs YML. What is YAML? YAML (Yet Another Markup Language or YAML Ain’t Markup Language) is a lightweight and easy-to-read format designed for structured data representation. It is commonly used in DevOps, CI/CD pipelines, and cloud configurations due to its simplicity and flexibility. Explore test automation best practices. Why Use YAML? ✅ Human-Readable Format – Uses indentation instead of brackets. ✅ Supports Complex Data Structures – Works with lists, dictionaries, and nested objects. ✅ Widely Used in DevOps & CI/CD – Used in Kubernetes, GitHub Actions, and Docker Compose. ✅ Compatible with Multiple Programming Languages – Works with Python, JavaScript, and more. Learn more about automation in software testing. YAML vs YML: What’s the Difference? There is no functional difference between .yaml and .yml file extensions. YAML originally used .yml due to 3-character file extension limitations, but modern systems support .yaml as the preferred standard. Feature .yaml .yml Standard Usage ✅ ✅ Preferred for New Projects ✅ ❌ Historical Limitation ❌ ✅ Compatibility ✅ ✅ Read about software configuration best practices. YAML Syntax Basics 1. Key-Value Pairs name: Keploy language: YAML version: 1.0 2. Lists in YAML languages: - Python - JavaScript - Go 3. Nested Objects database: host: localhost port: 5432 username: admin Explore how YAML is used in CI/CD workflows. Best Practices for Using YAML ✅ Use Consistent Indentation – Avoid tabs, use spaces. ✅ Keep It Simple – Avoid unnecessary complexity. ✅ Validate YAML Files – Use tools like yamllint. ✅ Avoid Tabs – Indentation should be with spaces only. ✅ Use Descriptive Keys – Maintain readability and structure. Learn how Keploy simplifies testing automation. Where is YAML Used? Kubernetes Configurations – Defining Pods, Services, and Deployments. GitHub Actions – Automating workflows. Docker Compose – Managing multi-container applications. CI/CD Pipelines – Automating builds and deployments. Infrastructure as Code (IaC) – Terraform and Ansible use YAML for automation. Read more about YAML vs YML. Conclusion YAML is an essential format for modern development, especially in DevOps, CI/CD, and automation. Whether using .yaml or .yml, developers should focus on proper syntax, indentation, and validation to avoid errors. Explore more about YAML and its applications. Would you like to include more YAML-related case studies or integrations with Keploy?

Mar 25, 2025 - 07:25

YAML is a human-readable data serialization format used widely in configuration files, APIs, and automation workflows. But what exactly is YAML, and is there a difference between .yaml and .yml? Learn more about YAML vs YML.

What is YAML?

YAML (Yet Another Markup Language or YAML Ain’t Markup Language) is a lightweight and easy-to-read format designed for structured data representation. It is commonly used in DevOps, CI/CD pipelines, and cloud configurations due to its simplicity and flexibility. Explore test automation best practices.

Why Use YAML?

✅ Human-Readable Format – Uses indentation instead of brackets. ✅ Supports Complex Data Structures – Works with lists, dictionaries, and nested objects. ✅ Widely Used in DevOps & CI/CD – Used in Kubernetes, GitHub Actions, and Docker Compose. ✅ Compatible with Multiple Programming Languages – Works with Python, JavaScript, and more.

Learn more about automation in software testing.

YAML vs YML: What’s the Difference?

There is no functional difference between .yaml and .yml file extensions. YAML originally used .yml due to 3-character file extension limitations, but modern systems support .yaml as the preferred standard.

Feature	`.yaml`	`.yml`
Standard Usage	✅	✅
Preferred for New Projects	✅	❌
Historical Limitation	❌	✅
Compatibility	✅	✅

Read about software configuration best practices.

YAML Syntax Basics

1. Key-Value Pairs

name: Keploy
language: YAML
version: 1.0

2. Lists in YAML

languages:
  - Python
  - JavaScript
  - Go

3. Nested Objects

database:
  host: localhost
  port: 5432
  username: admin

Explore how YAML is used in CI/CD workflows.

Best Practices for Using YAML

✅ Use Consistent Indentation – Avoid tabs, use spaces. ✅ Keep It Simple – Avoid unnecessary complexity. ✅ Validate YAML Files – Use tools like yamllint. ✅ Avoid Tabs – Indentation should be with spaces only. ✅ Use Descriptive Keys – Maintain readability and structure.

Learn how Keploy simplifies testing automation.

Where is YAML Used?

Kubernetes Configurations – Defining Pods, Services, and Deployments.
GitHub Actions – Automating workflows.
Docker Compose – Managing multi-container applications.
CI/CD Pipelines – Automating builds and deployments.
Infrastructure as Code (IaC) – Terraform and Ansible use YAML for automation.

Conclusion

YAML is an essential format for modern development, especially in DevOps, CI/CD, and automation. Whether using .yaml or .yml, developers should focus on proper syntax, indentation, and validation to avoid errors. Explore more about YAML and its applications.

Would you like to include more YAML-related case studies or integrations with Keploy?