The SDK, or Software Development Kit, allows developers to easily extend the features and capabilities of the ActiveWorlds software. ActiveWorlds, Inc. provides extensive documentation on the SDK.
The ActiveWorlds SDK is free to download and use, with some limitations. Testing SDK apps in ActiveWorlds requires at least one bot space on your account. New accounts created on or after June 14, 2013 may not have at least one bot space. Bot spaces cost 210 AW Credits (about $21 USD) and can be purchased here.