Third-party web APIs are becoming ever more popular as the API economy continues to grow. Software developers often integrate them into their own applications. The issue is that even if a developer thoroughly tests that their application works properly with the third-party web API, the owner of that API can completely change the code at any time, or take the API offline altogether, either temporarily or permanently. This makes for potentially less stable or reliable applications. This report attempts to determine what some of the factors are that most influence software developers’ trust in any given third party Web API. To do this, 42 individuals involved with software development were surveyed. Documentation and reliability came through as the strongest factors influencing their trust, but there is no general consensus on other factors. Further work could be done to confirm that these two factors are what influence developer trust the most, as well as work to determine which factor sought to influence developers’ trust in any given third-party web API, and thus work towards more reliable applications being developed as the API economy continues to grow.