AWS Cognito
AWS managed identity service — user pools for sign-up/sign-in with social and enterprise federation, access control, and MFA that scales to millions of users on AWS infrastructure.
Use Cases
Free Tier
10,000 MAU/month free forever (Lite/Essentials tiers, direct + social sign-in); 50 free MAU for SAML/OIDC federation
How to Maximize the Free Tier
Cognito's free tier is 10,000 MAU per month per account for users who sign in directly or via social identity providers on the Lite or Essentials tiers — and unlike the general AWS Free Tier, it does NOT expire after 12 months. The catch is federation: SAML/OIDC enterprise users only get 50 free MAU before $0.015/MAU, and the Plus tier (advanced security features) has no free tier at all, so keep pools on Lite/Essentials unless you truly need ASF. Above 10K MAU, direct sign-ins run ~$0.0055/MAU, and MFA SMS is billed separately via SNS. Set up AWS Budgets alerts from day one to avoid surprise bills. Combine with AWS Amplify for the fastest integration or use the hosted UI for a ready-made login page; identity pools for unauthenticated guest access are free.
Getting Started
Create an AWS account → open the Cognito console → Create user pool → choose sign-in options (email, username, social IdPs) → set password policy and MFA → create an app client → use the hosted UI or Amplify SDK in your app → call InitiateAuth for sign-in and validate the returned JWT with the AWS JWT verifier in your backend.
Pros
- Scale: Fully managed by AWS — handles millions of MAU with built-in high availability
- Free tier: 10K MAU/month free forever for direct + social sign-in, with no 12-month expiry
- Federation: SAML 2.0 and OIDC enterprise federation plus social IdPs for B2B apps
Cons
- Complexity: AWS console, IAM, and pool configuration have a steeper learning curve than dedicated auth SaaS
- Fee layers: Federated (SAML/OIDC) MAUs cost $0.015/MAU above just 50 free; the Plus tier has no free tier
- Lock-in: Deep AWS integration makes migrating user pools to another provider a manual effort