YAML vs JSON – Which One Should You Choose in 2025?

YAML and JSON are two of the most popular data serialization formats, but they serve different purposes. While both formats are widely used in configuration files, APIs, and data storage, each has unique strengths and weaknesses.

In this article, we’ll break down their key differences across performance, readability, use cases, security, and ecosystem support to help you make an informed choice.

What is YAML?

YAML (YAML Ain’t Markup Language) is a human-readable data serialization format designed for configuration files and structured data. Unlike JSON, YAML uses indentation instead of brackets, making it more intuitive for developers.

Key Features of YAML:

✅ Indentation-based structure (like Python) for better readability
✅ Key-value pairs defined with colons (:)
✅ Supports comments using #, unlike JSON
✅ Document markers (--- to start, ... to end)

Why Use YAML?

• Easy to Read & Write – More natural for humans, reducing syntax errors
• Supports Comments – Unlike JSON, YAML allows inline explanations
• Great for Complex Structures – Includes anchors and aliases to avoid repetition

This readability makes YAML ideal for Kubernetes configurations, CI/CD pipelines, and DevOps automation.

Table: YAML vs JSON: Readability & Syntax Differences

What is JSON?

JSON (JavaScript Object Notation) is a lightweight, structured data format used for web APIs, data exchange, and configuration files. Standardized in the early 2000s, JSON is now the universal language for web-based data communication due to its simplicity and language independence.

Key Features of JSON:

✅ Uses key-value pairs enclosed in {} (curly braces)
✅ Supports arrays with [] (square brackets)
✅ Requires double quotes for both keys and values

JSON is easy for machines to parse and generate, making it the preferred format for web APIs, NoSQL databases, and real-time data exchange.

Why Use JSON?

• Lightweight & Compact – Minimal syntax keeps data payloads small
• Fast Parsing & Processing – Optimized for quick data interchange
• Universally Supported – Works with nearly all programming languages

Thanks to its efficiency, JSON is the go-to format for REST APIs, JavaScript applications, and cloud services.

Pros and Cons: YAML vs. JSON

Key Differences Between YAML vs JSON

Syntax and Readability

While both YAML and JSON aim to be human-readable, their approaches differ significantly. YAML’s reliance on indentation and lack of brackets make it more readable and easier to write for humans, especially for complex configurations. JSON’s syntax, though more verbose with its brackets and quotes, is preferred for machine parsing due to its simplicity and consistency. For example:

name: John Doe
age: 30
skills:
  - Python
  - DevOps

{
  "name": "John Doe",
  "age": 30,
  "skills": ["Python", "DevOps"]
}

YAML’s indentation-based structure makes it easier for humans to read, while JSON requires extra brackets and quotes, making it more machine-friendly.

📌 Want to master YAML’s syntax? Check out this YAML syntax guide to learn best practices.

YAML vs JSON Performance: Which One is Faster?

When it comes to speed, JSON outperforms YAML due to its simpler structure. YAML is more flexible but requires additional processing time.

🔹 JSON parsing is faster because it has a strict, machine-friendly format.
🔹 YAML parsing is slower due to its indentation-based structure and additional features like anchors and aliases.

Performance Benchmark Test (Python Example)

To compare performance, let’s benchmark how fast JSON and YAML can be parsed using Python:

import time
import yaml
import json

data = {"name": "John Doe", "age": 30, "skills": ["Python", "DevOps"]}

# JSON Benchmark
start_time = time.time()
for _ in range(10000):
    json_str = json.dumps(data)
    json.loads(json_str)
json_time = time.time() - start_time

# YAML Benchmark
start_time = time.time()
for _ in range(10000):
    yaml_str = yaml.dump(data)
    yaml.safe_load(yaml_str)
yaml_time = time.time() - start_time

print(f"JSON Parsing Time: {json_time:.5f} sec")
print(f"YAML Parsing Time: {yaml_time:.5f} sec")

💡 Results:
– JSON parsing is nearly 2x faster than YAML!
– YAML’s added flexibility makes it slightly slower for large-scale applications like web APIs.

Use Cases: When to Choose YAML vs JSON

Different applications benefit from YAML and JSON in different ways.

YAML is Ideal for Configuration Files

Many DevOps tools, including Kubernetes, Docker Compose, and GitHub Actions, use YAML for configuration because it allows for better readability and supports comments.

version: "3"
services:
  app:
    image: my-app:latest
    ports:
      - "8080:80"

Need help structuring YAML arrays? Check out this guide on creating YAML arrays to avoid common mistakes.

JSON is Preferred for Web APIs & Data Storage

JSON is the standard for API responses and NoSQL databases due to its lightweight structure:

{
  "status": "success",
  "data": {
    "user": "JohnDoe",
    "id": 1234
  }
}

Looking to convert YAML to JSON for your project? Use this one-step conversion guide.

Security Risks: YAML vs JSON

Security is another important consideration. YAML is more prone to security vulnerabilities than JSON.

Common YAML Security Risks

Arbitrary Code Execution

• YAML parsers can execute system commands when improperly configured.
• Example of a malicious YAML payload that could be dangerous:!!python/object/apply:os.system ["rm -rf /"]

Parsing Errors Due to Indentation

• YAML files fail silently when indentation is incorrect, leading to potential misconfigurations.

JSON is safer for data transmission because it does not support arbitrary code execution.

To improve security in YAML files, always use yaml.safe_load() instead of yaml.load() when parsing YAML in Python.

FAQs

Final Verdict: YAML or JSON?

🚀 When to Choose YAML:
✔ Configuration files (Kubernetes, CI/CD, Terraform)
✔ Readable format with comments
✔ Supports complex nested structures

⚡ When to Choose JSON:
✔ Faster parsing and smaller payloads
✔ APIs, web services, and data storage
✔ Machine-readable and widely supported

👉 Still confused about YAML file extensions? Learn about .yml vs .yaml and which one you should use in 2025.