Same-Origin Policy Deep Dive — The Browser Security Model Behind CORS

In this tutorial, you will learn about Same. We cover key concepts, practical examples, and best practices to help you master this topic.

The same-origin policy is the foundational browser security model that restricts how documents and scripts from one origin can interact with resources from another origin, defining protocol, host, and port as the origin boundary.

What You'll Learn

• How SOP protects DOM, storage, and network access
• Cross-origin writing vs reading rules
• Legitimate cross-origin mechanisms

Why It Matters

Understanding SOP is essential for web security. Every CORS configuration is an exception to SOP. Without SOP knowledge, you cannot reason about web security. Doda Browser implements SOP Compliance in its rendering engine.

flowchart TD
    subgraph "SOP Protections"
        DOM["DOM Access"]
        STO["Storage (Cookies, LocalStorage)"]
        NET["Network Responses"]
    end
    DOM -->|"Cross-origin blocked"| B1["Cannot read iframe DOM"]
    STO -->|"Cross-origin blocked"| B2["Cannot read other origin's cookies"]
    NET -->|"Cross-origin blocked"| B3["Cannot read fetch responses"]
    subgraph "Exceptions"
        C1[",