No we do not limit monthly bandwidth in anyway. We allow you to fully utilize the network and burst traffic without limits.

But do you throttle traffic, so that when it reaches a certain amount within a certain time period, it drops to a slower speed?

We do not throttle bandwidth or traffic after a certain amount. From time to time you may speed different bandwidth speeds depending on internet conditions, load on your droplet, or the system as a whole.

Do you guarantee any speed, and what is upper limit for one Droplet?

@creating.www: All droplets are on 1Gbps ports.