Apache Traffic Server vs cache2k

Apache Traffic Server is a free, open-source caching proxy server for HTTP/1.1 and HTTP/2. It stores frequently requested pages, images, and web service calls so they can be reused, with the stated aims of improving response time and reducing server load and bandwidth needs. It can also add keep-alive behavior, filter or anonymize requests, and balance traffic through a proxy layer. Deployment patterns include web proxy cache, reverse proxy, and cache hierarchy. As a layer 7 HTTP load balancer, it can choose next-hop servers using request attributes, weighted round robin, or URL consistent hashing. Plug-in APIs let teams add behavior such as changing headers, handling ESI requests, or implementing cache algorithms. Security options include client access controls and authentication, SSL termination, and SSL-based access control. It is self-hosted, with Linux and macOS listed as platforms. The project identifies enterprises, internet service providers, backbone providers, and large intranets as its intended audience. The listed stable release is 10.2.0; 9.2.15 is listed as the long-term support release.

cache2k is an Apache-licensed, open-source library that keeps Java application objects in memory. Its project describes a JAR smaller than 400 KB with no external dependencies, and the implementation is written in pure Java without sun.misc.Unsafe. Cache behavior includes automatic expiry, refresh, refresh ahead, read-through loading, and event listeners. Cache loaders can suppress exceptions or retry them according to configuration. Integrations listed include Spring Framework, Scala Cache, DataNucleus through JCache, and Hibernate through JCache. cache2k supports JCache / JSR 107, while its guide notes extra overhead for that API compared with the native interface. Monitoring options include low-overhead statistics, JMX, and documented Micrometer metrics. Version 2 requires Java 8 or later and is described as compatible with Android API level 26. The library is free, available from Maven Central, self-hosted, and does not persist data.