Twilio PM: a scenario plan for API limits across customer, platform and upstream-provider sides

You are a product manager for Twilio's communications APIs. How would you deal with the limits on your API? Describe the scenarios that can come up on the customer side, the technology side and the supplier side, and how you would address each. ```hint Sort the limits by where they come from Before listing fixes, separate the limits you choose to set, the limits your own systems run into and the limits placed on you from upstream; each kind needs a different response. ``` ### Clarifying Questions - Which API do you have in mind: messaging, voice or another product? The limits that matter differ by channel. - By "API limits", do you mean the request and throughput caps we place on customers, the capacity ceilings of our own systems, the caps upstream networks place on us, or all of these? - Is something prompting this, such as customers complaining about throttling or an expected traffic surge, or is it a general review of our limit policy? - When the goals conflict, which comes first: platform reliability, customer growth or cost to serve? ### What a Strong Answer Covers - Which limits are in scope, where each one comes from and why it exists - Concrete scenarios on the customer, technology and supplier sides, with who is affected and how badly - A response for each scenario across product, policy, engineering and communication levers, with its trade-offs - What a customer experiences before, at and after hitting a limit - A prioritized plan and the signals that show limits are hurting customers or the platform ### Follow-up Questions - A large customer wants to send a one-time burst far above its limit next week. How do you decide whether and how to support it? - An upstream network suddenly lowers the throughput it accepts on a route many customers use. What do you change, and what do you tell those customers? - Should higher limits be something customers pay for? What could go wrong if they are?