Recently updated to v1.6.1, the KSP Trajectory Optimization Tool (KSP TOT) is a piece of MATLAB-based software written to help plan and execute space missions. 

It's functions are many:

Using a Lambert solver, generate "porkchop plots" that assist with determining proper departure and arrival times of interplanetary transfer orbits.

Determine an optimal hyperbolic departure orbit and compute the burn magnitude and direction (that is, the delta-v vector) as well as the burn location in the initial orbit about the departure planet.

Compute optimal planetary flybys to cheaply get to those hard-to-reach destinations (Moho, Eeloo, etc).

Generate delta-v optimal rendevzous maneuvers to another spacecraft.

Find the optimal two-burn orbit change maneuvers to adjust your orbit cheaply!

Fully sequence a mission from start to finish, including coasts, burns, aerobraking, and more.  

Click here to get it!