CSP/INSCR Coup Data
http://www.systemicpeace.org/inscrdata.html (Scroll down to find the link to the codebook and data)
It codes not only successful coups but also failed coups and alleged coup plots in countries with population more than 50,000 for 1946-2014.
Powell, Jonathan & Clayton Thyne. 2011. "Global Instances of Coups from 1950-Present." Journal of Peace Research 48(2):249-259
The data has been updated "near-real time". Used by Erik Meyersson's working paper (as of 2015) entitled "Political Man on Horseback: Military Coups and Development".
Coup D'état Project (CDP) by The Cline Center for Democracy
Compiled by the "Big Data" method (see this page for detail).
McGowan (2003) "African military coups d’etat, 1956-2001: frequency, trends and distribution," Journal of Modern African Studies, 41:3, pp. 339–370
For African countries, Patrick J. McGowan has compiled detailed information on every successful and unsuccessful coup and every coup plot from 1955 through 2006 (with sources of information explicitly mentioned).