OAuth2 Grant Type Selection — Choosing the Right OAuth2 Flow for Your Application

In this tutorial, you will learn about OAuth2 Grant Type Selection. We cover key concepts, practical examples, and best practices to help you master this topic.

OAuth2 grant type selection helps you choose the right authorization flow for your application type — web app, mobile app, SPA, CLI tool, IoT device, or server-to-server — balancing security requirements with user experience.

What You'll Learn

• Grant type selection criteria
• Client type categorization (confidential vs public)
• Security requirements per flow
• Grant type combinations and fallbacks
• Migration between grant types

Why It Matters

Choosing the wrong grant type creates security vulnerabilities or poor user experience. Using the Implicit Grant (deprecated) for SPAs exposes tokens in URLs. Using Client Credentials for user-facing apps is a design error. DodaTech's developer documentation provides grant type recommendations per client scenario.

flowchart TD
    A["What type of client?"] --> B{"Has a backend
server?"}
    B -->|"Yes"| C["Confidential Client"]
    B -->|"No"| D{"Can securely store
a secret?"}
    D -->|"Yes"| E["Mobile App"]
    D -->|"No"| F["SPA / Browser"]

    C --> G["Authorization Code Grant"]
    E --> H["Authorization Code + PKCE"]
    F --> I["Authorization Code + PKCE"]
    G --> J{"User interaction
needed?"}
    J -->|"No"| K["Client Credentials
(machine-to-machine)"]
    J -->|"Yes"| G

    C --> L["Refresh Tokens"]
    E --> L
    F --> L
    H --> M{"Device has
limited input?"}
    M -->|"Yes"| N["Device Authorization Grant"]

What's Next

Explore specific grant types: {{< ilink "OAuth" "Authorization Code Grant" }}, {{< ilink "OAuth" "PKCE Extension" }}, {{< ilink "OAuth" "OAuth2 Client Credentials Grant" }}, and {{< ilink "OAuth" "OAuth2 Device Authorization Grant" }}.