The "build vs. buy" question is a common consideration in technology development. In the case of adding realtime features to an online learning platform, evaluating third-party vendors like Ably can be crucial for time and cost efficiency. Key factors to consider when choosing a vendor include scalability, integration capabilities, security measures, data compliance, and pricing plans. By using a platform like Ably, businesses can avoid the complexities of building their own realtime solution while benefiting from its fault-tolerant infrastructure, global edge network, and support for various protocols and APIs.