oson,

http://stackoverflow.com/questions/3459795/how-to-choose-between-jersey-apache-wink-and-jboss-resteasy JAX-RS Implementations

Jersey

Reference Implementation
Usually the most cutting edge
Supports true asynchronous (ie web sockets etc...) connections through either Atmosphere or 2.0 version.
Has support for Spring and standard injection containers (ie @Inject).
Glassfish bundles it.
Does not require a servlet container.
Its much more modular than the other JAX-RS projects.
It has a kick ass URI Builder
Does not necessarily require servlet container.
Grizzly support
Netty support (very early).
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Restlet

Very powerful but very complicated
Provides some low-level REST support
Does not require a servlet container

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