You can kick the tires of Sync Gateway by downloading it and just running "./sync_gateway" with no arguments. This will start up a little in-memory database and serve it at
http://localhost:4985/sync_gateway/ .
Then you can build a minimal Couchbase Lite demo app like Grocery Sync, set the remote db URL to the above, and try it out.
(The more complex demo apps require a sync function to be configured in the gateway; these apps should come with a JSON file for configuring the gateway. You can set up the gateway for these by editing the config file and changing the "server": definition to
"server": "walrus:",
(to make it use the simple in-memory db instead of Couchbase Server) and then starting sync_gateway with the config file as the argument.
—Jens