Third-party APIs are crucial to software systems, and their performance can significantly impact user experience, necessitating robust monitoring similar to that applied to internal code and platforms. Using tools like Dynatrace Real User Monitoring (RUM), organizations can effectively track the performance and impact of these APIs, as demonstrated in a case involving a financial sector customer who used Dynatrace to monitor a self-service portal for insurance agents. By configuring Dynatrace to monitor both internal and external access points of the portal, the team identified a spike in HTTP 500 errors linked to an internal third-party API managed by a different team, which was affecting both internal and external users. This proactive monitoring allowed the team to address the issue before it led to widespread user complaints or support calls, highlighting the value of real-time alerts and insights in maintaining software reliability. Additionally, Dynatrace offers integrations with tools like Slack and Jira for automated problem notifications, further enhancing its utility in managing API-related issues.