Traditionally, the impact of research articles has been measured by the publication journal. But a more informative view is one that examines the overall performance and reach of the articles themselves. Article-Level Metrics (ALM) capture the manifold ways in which research is disseminated and used.
From: Fenner M, Lin J (2013). Altmetrics in Evolution: Defining & Redefining the Ontology of Article-Level Metrics. http://doi.org/10.3789/isqv25no2.2013.04.
The collection of metrics shouldn't be limited to journal articles, but should include all relevant research outputs, e.g. datasets (data-level metrics) and software (software-level metrics).
Lagotto is an Open Source application started in March 2009 by the Open Access publisher Public Library of Science (PLOS). Lagotto retrieves data from a wide set of services (sources). Some of these sources represent the actual channels where users are directly viewing, sharing, discussing, citing, recommending the works (e.g., Twitter and Mendeley). Others are third-party vendors which provide this information (e.g., CrossRef for citations).
The following organizations are using Lagotto (live status information available here):
Users can access the data via the API, or via one of the client applications: