For what reasons is using In-Memory Cache undesirable in conjunction with REST API?

Using In-Memory Cache together with REST API is undesirable for several reasons:

• Lack of data consistency: The cache is stored locally on the server, and during scaling (multiple API instances), data may diverge.
• Scalability issues: As the number of servers increases, each will have its own cache, complicating synchronization.
• Data loss on restart: In-memory cache disappears when the server restarts, which may require re-fetching data.
• Lack of distribution: Unlike distributed caches (Redis, Memcached), In-Memory Cache is not suitable for cluster solutions.

Therefore, it is generally recommended to use external distributed caches for REST API, which ensure consistency and scalability.