A primary concern when utilizing third-party APIs is the risk of security vulnerabilities. Since these APIs often involve sensitive data transfer, improper implementation can expose applications to threats like data breaches and unauthorized access. Developers must also be wary of dependency on third-party systems, which can lead to issues if those services become unavailable or slow down. Additionally, the use of third-party APIs can complicate compliance with data protection regulations. Therefore, it's essential to assess the credibility and reliability of API providers and implement best practices for security.