jboss-javassist/javassist

Health v2 · maintenance only

Flags: no_license

Adoption not part of the score

4228 stars · 717 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

Javassist is a Java class library for editing Java bytecode, enabling programs to define new classes at runtime or modify class files as the JVM loads them. It offers both a source-level API (editing classes using Java syntax without bytecode knowledge) and a bytecode-level API for direct class file manipulation.

Use cases

• generate new Java classes at runtime
• instrument Java classes as the JVM loads them
• modify class files without knowing bytecode internals
• build AOP frameworks or proxies in Java
• add logging or tracing to existing Java classes
• patch third-party Java libraries at load time

When to choose

• you need runtime class generation or bytecode transformation on the JVM
• you want to edit classes using Java source syntax instead of raw bytecode
• you're building frameworks like ORMs, AOP tools, or mocking libraries

When to avoid

• you need bytecode manipulation on non-JVM languages
• you only need runtime reflection without class modification
• you need a higher-level agent framework rather than a bytecode library

Facets

library · maturity stable

compiler parser developer-tools developer-tools programming-languages compilers jvm bytecode-manipulation java-bytecode runtime-class-generation instrumentation aop

Member repositories

For agents

markdown · JSON · MCP: product_card(name="jboss-javassist/javassist")