How LinkedIn Authorizes 10 Million API Calls Per Second

LinkedIn utilizes Access Control Lists (ACLs) to manage access control at scale, facing challenges such as quick authorization checks, prompt ACL changes delivery, managing a large number of ACLs, and monitoring ACL data. They handle these challenges by running an authorization client module on every service, periodically refreshing ACL data, storing ACLs in a database with a cache, and logging authorization checks for monitoring purposes.