Information presented here is intended to assist developers who are integrating Nxt with their existing sites (games, applications, exchanges, etc.) Currently, developers must implement solutions "from scratch"; however, several people are working on toolkits for easy site integration, and those will be linked here once they are available.
Guides linked from this page are written to use the high-level API for Nxt, which uses JSON. Once you get a feel for the API calls, you may prefer to implement your system using the low-level Java API. Javadoc documentation for this is available in the /doc subdirectory of the Nxt software distribution.
Wesley's guide has examples of how to handle Nxt deposits and withdrawals.
As toolkits are made available, they will be listed here.
Testing Your Implementation
For creating and testing your automated system, you can take advantage of the testnet server located at http://holms.cloudapp.net:6874, or run your own server, on port 6874, using holms.cloudapp.net as a peer. Once your system is up and running, you can move to your own server OR set up a new server on port 7874 to access Nxt's live network.
To get testNxt to use on the testnet, simply post your testNet address on the dedicated thread on the nxt forum or alternatively on the bitcointalk forum thread for Nxt. Developers who are constantly testing features will be able to send you some.