Full featured API checker for Java and beyond.

Revapi is an API analysis and change tracking tool written in Java.

Its focus is mainly on Java language itself but it has been specifically designed to not be limited to just Java. API is much more than just java classes - also various configuration files, schemas, etc. can contribute to it and users can become reliant on them.

Revapi is in beta. The Java API checker is fairly capable and can track both binary and source compatibility and the maven plugin and ant task are fairly useful but there are still many things to be done and polished. Your help is greatly appreciated.


Because surprisingly there doesn’t seem to exist a simple yet extensible, developer-oriented tool that could be used to check the APIs and, more importantly, track their evolution. APIs are not static, they evolve to accommodate new features and past mistakes but at the same time, each change in the APIs potentially breaks the code of the users of the APIs.

It is therefore important for the tool to do 2 things right:

  1. correctly identify all changes in an API, be it Java code, configuration files, descriptor files of any sort, etc.

  2. allow the developer to mark selected changes as intentional (unavoidable changes in API are sometimes necessary).

Prior Art


SigTest is a tool from Oracle itself to track API coverage and API evolution. It is functionally very close to what revapi aims to be but has a couple of drawbacks that make revapi worthwhile to look at:

  • while there is a maven plugin for SigTest, it is not available in Maven Central

  • the maven plugin cannot check api changes (yet)

  • it cannot track intentional API changes

  • it relies on generated "signature" files instead of directly comparing jars

There is also an alternative Maven plugin for the tool,, which seems to support checking for API changes.


A new kid on the block, conceived at roughly the same time as Revapi. Currently, it only supports checking for binary compatibility of Java archives. It has a Maven plugin and a CLI and is able to produce HTML reports of found differences.


Clirr is another tool, that is functionally quite close to what revapi aims to be. It has a nice maven plugin (developed separately, working around limitations of the stale Clirr library itself), it is able to directly compare 2 jar files for changes and it is even possible to ignore the intentional API changes.

The main drawback of Clirr is that it is essentially dead with last release in 2005. Also, it is tightly coupled to Java and has no abstraction over language or "structure" it can check.

Animal Sniffer

While Animal Sniffer in essence does API checks, it’s intended for different purpose than API change tracking. Animal Sniffer is meant to check that a codebase doesn’t call API methods not present in a library it uses. While this may sound strange, this happens if you compile against a new version of a library but use an old version of it at runtime. Typically, this happens with Java runtime library itself, when a Jar is compiled against a later version of JRE than it is then run on.

Getting Involved

Your contributions of any kind, be it a bug report, idea or even code contribution, are greatly appreciated. You can get in touch on the following places:




GitHub issues


start here


@[email protected]




Mailing list

[email protected]