Solon
A Java enterprise application framework built as a full alternative to Spring, aiming for higher concurrency, lower memory use, and much faster startup.
Solon is a Java framework for building enterprise applications across microservices, RPC, and REST APIs, built from scratch with its own interface specifications rather than on top of the Java EE/Servlet stack. It reports much higher concurrency and lower memory use than comparable frameworks in its own benchmarks, along with substantially faster startup and a smaller packaged size, and supports Java 8 through Java 26, including GraalVM native images.
Its ecosystem spans plugins for Maven, Gradle, IntelliJ IDEA, and VS Code, a cloud module, a flow and expression engine, an admin console, and integration with LLMs and MCP servers, plus companion projects reimplementing tools such as Claude Code and OpenClaw for the Solon/Java ecosystem. It is licensed under Apache 2.0.