AWS IAM vs Amazon Cognito: What are the differences?

AWS IAM (Identity and Access Management) and Amazon Cognito, both services are offered by Amazon Web Services (AWS) and provide different functionalities for managing user identities and access to resources. Let's discuss the key differences between the two:

1. Scalability and User Management: AWS IAM is primarily designed for managing access to AWS resources within an organization. It allows administrators to control user identities, their permissions, and access to various AWS services. On the other hand, Amazon Cognito is a fully managed authentication service that provides scalable user management capabilities for web and mobile applications. It offers features like user sign-up and sign-in, social identity providers integration, and multi-factor authentication.

2. Federated Identity and User Pools: AWS IAM supports federated identity through its Identity Providers feature. This allows users to log in to AWS services using their existing identities from external providers like Active Directory or Facebook. Amazon Cognito, on the other hand, provides user pools which are user directories that enable sign-up and sign-in functionality for applications. User pools also support social identity providers integration and can be used as federated identity providers for AWS services.

3. Temporary Credentials and Access Control: AWS IAM allows users to generate temporary credentials to access AWS resources for a limited duration. These credentials can be used by applications or services to access resources securely without storing permanent credentials. Amazon Cognito, however, provides a different approach to access control using identity pools. Identity pools allow applications to exchange user authentication for temporary, limited-privilege AWS credentials. This enables fine-grained access control based on user attributes and roles.

4. Single Sign-On (SSO) and Identity Federation: AWS IAM supports Single Sign-On (SSO) through the use of SAML (Security Assertion Markup Language) or OpenID Connect identity providers. This enables users to sign in to the AWS Management Console and access multiple AWS accounts or applications without separate authentication. Amazon Cognito also supports SSO but focuses more on decentralizing authentication for applications using user pools or social identity providers.

5. Pricing Model: AWS IAM is mainly included in the overall pricing of AWS services and is not charged separately. However, some additional features like IAM roles for EC2 instances may have associated costs. Amazon Cognito, on the other hand, has its own pricing model based on the number of monthly active users and the amount of data stored. It offers different pricing tiers based on the specific needs of applications and the desired level of scalability.

6. Integration and Use Cases: While AWS IAM is tightly integrated with AWS services and is commonly used within organizations for managing access to AWS resources, Amazon Cognito is more suitable for web and mobile applications that require user authentication and authorization capabilities. It provides out-of-the-box integration with mobile SDKs and web frameworks, making it easier to implement user management functionality in applications.

In summary, AWS IAM focuses on managing access to AWS resources within an organization, while Amazon Cognito provides scalable user management for web and mobile applications with features like user sign-up, sign-in, federated identity, and single sign-on capabilities.