Amazon ElastiCache vs Memcached

Amazon ElastiCache is a managed caching service compatible with Valkey, Memcached, and Redis OSS, with performance described as microsecond latency. Customers can deploy a serverless cache or a node-based cluster. ElastiCache Serverless monitors compute, memory, and network use and scales vertically and horizontally as demand changes. It replicates data across multiple Availability Zones and offers a 99.99% availability SLA for each cache. Listed uses include application and semantic caching, data and session stores, and leaderboards. It can act as a front-end cache for Amazon RDS, Aurora, DocumentDB, and DynamoDB, and improve performance with EC2 and EMR. Security options include encryption in transit and at rest, IAM authentication, Valkey or Redis OSS AUTH, and role-based access control. CloudWatch provides more than 40 operational metrics at no additional charge. Valkey serverless pricing starts at $6 a month, billed according to stored data in GB-hours and requests measured in ECPUs. Data tiering is unavailable with ElastiCache Serverless.

Memcached is a free, self-hosted in-memory key-value cache for reducing database load in dynamic web applications. It keeps small chunks of arbitrary data, such as strings, objects, and results from database calls, API calls, or page rendering. Clients use key-based hashing to choose a server, while servers operate independently without synchronization or replication. Items can expire after a specified time, and the default eviction policy is least recently used (LRU). The project describes Memcached as a developer tool, not code acceleration software or database middleware. Its API is available for most popular languages, and downloads include a source tarball and installation instructions with package prerequisites for Debian/Ubuntu and Red Hat/CentOS. TLS authentication and encryption are supported in version 1.5.13 and later when built with TLS and used with a TLS-capable client. Optional extstore moves values to external storage while keeping keys and the hash table in memory; it needs version 1.6.0 or newer. The project began in 2003. It is free and self-hosted, with no hosted plan or price listed.