As a developer, you don’t like reinventing the wheel. You need to add authentication and authorization to your and you’ve decided to use a third-party service, instead of rolling your own users management system. You are familiar with , so is the way to go. You check the docs and try to understand what is , what is and what is the difference between them. API AWS Cognito User Pools Identity Pools No worries, we’ve all been there. It’s really confusing, specially if you’re not an expert on authentication and authorization protocols (I include myself there). Both services seem to be built for the same purpose, so choosing one or another can become a tough task. Long story short If you’d like to from the client side (be it a mobile or a web app), use . Go for . access AWS resources directly Cognito Identity Pools (CID) User Pools (CUP) otherwise I trust you, but what’s the deal? Even though User Pools and Identity Pools seem to be similar, there are some aspects that make them quite different. First, we should pay attention at what the outcome of the authorization process is in both cases. provides us with a so we can use it as an authorizer for any existing API, while with we get , which means that is meant to utilize AWS resources. We can definitely use it as an API authorizer, but only if it’s exposed through AWS API Gateway. User Pools , JSON Web Token Identity Pools temporary AWS credentials Taking note of what is the type of credentials delivered by CUP and CIP made me realize which use cases each service is suited for, although there are more features that could make you lean on one or another. With you get the whole , you’ll be able to let your users sign up with their email and password (and additional attributes if you like), or through another identity provider, such as Facebook or Google. You can also include additional security measures, like , or have a customized sign up flow, by verifying users’ emails or mobile phone numbers. On the other hand, doesn’t count with an users directory, it fully relies on trusted for authentication . Some other feature supported by is and support of , which would allow third-party applications access your users’ accounts on their behalf and open up your secure API to the Internet. CUP users management system Multi-Factor Authentication CID third-party identity providers CUP OAuth2 compliance scopes In brief, you could follow the flowchart below to help you choose the service you want based on your needs: Cognito User Pools or Identity Pools depending on your needs Common use cases You can see below some common scenarios where you could be hesitating about which service suits your needs: if what you’re aiming for is using AWS as sort of a , you should use . By getting AWS credentials, you could query DynamoDB tables directly from the client or publishing an SNS notification, for example, straight away from the client side. If you are building a JavaScript app, it’s worth taking a look at the library. I’d like to access AWS services directly from my mobile app: Backend as as service CID AWS Amplify in this case, is the way to go. It relies on the JSON Web Token technology, so you can pretty much decode and verify the signature of the token from any web application. I’d like to secure an API not exposed by API Gateway: CUP again, CUP is the winner here. It’s OAuth2 compliant and let’s you define . I’d like to give access to my users’ data to another applications: custom scopes in this scenario you could pick any of them. With CID you basically have to define a IAM Role to set the users’ permissions, which can be as granular as you want. On the other hand, with CUP, the built-in only checks if the provided token is valid, but you can always create a custom one and define the permissions you need in combination with . I’d like to add fine-grained permissions based on user types in API Gateway: API Gateway authorizer CUP Groups Conclusion Cognito is a confusing AWS service and, let’s be honest, its documentation doesn’t help. However, as soon as you get your head around the fundamentals of its variations, the choice between them becomes easier. I hope this article helped you to understand them better!
