Metrics Toolkit
Metrics Toolkit is a resource for researchers and evaluators that provides guidance for demonstrating and evaluating claims of research impact. It provides guidance on available metrics, what they mean, how they are calculated, and whether they are a good match for your impact need.
Selected Traditional & Alternative Metrics Compared
Utrecht LIbrary provides a useful comparison of Traditional & Alternative Metric Tools The chart below is used with their permission via a Creative Commons License. 
Notes:
a Only items/persons/users included in the system (depends on data collected/uploaded by the users)
b Paid services: Mendeley Institutional Edition / Altmetric Institutional Edition / Altmetric Explorer
c With restrictions/limitations
d Article level metrics (Mendeley, Altmetric) and author profiles (ImpactStory) free to view