Regardless of the sport, Fantasy Pros is a must-visit for preparing for your draft. They do a really nice job here. While they can be a bit expensive, you're really getting a lot of tools for that price across multiple sports.
The MLB and NBA daily projections that are used with the optimizer and all corresponding DFS tools are created in-house. NFL weekly projections are aggregated from several trusted sources, such as CBS, numberFire and STATS to name a few.