To run i2psnark's standalone mode make sure you have an i2p router running in the background, then run:

java -jar i2psnark.jar

I2PSnark web ui will be at http://127.0.0.1:8002/i2psnark/ 

Please note that http://127.0.0.1:8002/ will 404, to be fixed

I2PSnark is GPL'ed software, based on Snark (http://www.klomp.org/) to run on top of I2P
(https://geti2p.net/) within a webserver (such as the bundled Jetty from
https://www.eclipse.org/jetty/).  For more information about I2PSnark, get in touch
with the folks at http://forum.i2p2.de/