Uppsala Conflict Data Program
The Uppsala Conflict Data Program (UCDP) includes several datasets on conflict and peace-building, with most updated annually. The UCDP Conflict Encyclopedia (UCDP database) provides descriptions of conflicts, peace agreements and related material, covering the period since the end of World War II.
Stockholm International Peace Research Institute (SIPRI)
Includes datasets on arms transfers, military expenditures, arms production, and peace operations. Publishes an annual yearbook.
Armed Conflict Location & Event Data Project
Focuses on political violence in developing states, especially in Africa. Details the types of events, locations, dates, deaths, and groups involved for a range of types of political violence. Covers governments, rebels, and protestors, and includes recruitment activities. Constantly updated.
Peace Research Institute Oslo (PRIO)
Includes data on armed conflict, the arms trade, governance, international trade, and houses the replication datasets for the Journal of Peace Research. Also includes a bibliography of references of specific conflict events.