Just finished Day 15 of FBSweat.

It was a bodyweight HIIT routine that kicked my butt and had me sweating! I had to take a few extra small breaks, but was glad to see that I didn't have to modify much at all and was able to keep up with a 4/5 difficulty HIIT workout.

32 minutes total and felt like I got a great workout.
If I'm feeling up to it later I may do the extra credit routine for today, which is a 20 minute long lower body/pilates/barre routine. Depends on how I feel later though.
Here is a link to the workout, no equipment needed except yourself!

Not for beginners but she does offer modifications throughout the routine:
Bodyweight HIIT Workout: