What obstacle database sources are used in ForeFlight's runway analysis?

AC 120-91A and the ICAO equivalent do not limit obstacle consideration to a specific set. Instead, it is encouraged to consider all obstacle data sources available. ForeFlight considers and continually updates obstacles included in the analysis. This includes close-in obstacles found near the airport and runway environment. In addition, the user has the ability to add obstacles manually, which is useful for temporary obstacle consideration provided via NOTAM.