I worked at Efficio part-time
Very good company to work for. Steep learning curve, but given a lot of responsibility out of the gate. Very good training and support system.
Long working hours, although this should be expected for a consulting company.
First step was an online test, then a phone screen, asked standard questions plus a few about procurement experience, then day long interview process where you had two separate interviews with two people each and an excel test. The first interview they asked some short brain teasers where you had to showcase your mental math ability and some basic questions. The second was a short case interview with some fit questions. The excel test wasn't too difficult if you know some basic functions, you don't really even need pivots.