6 Tips from a System Design Expert: How Twilio Builds for Scale

These six design themes draw on Mark Gilbert’s account in a 2022 webinar about Twilio, where he discussed his experience as a former VP of Product Management. The organizational details and workload figures describe that historical account. The exercises below use its themes to practice reasoning about capacity, dependencies, service boundaries, and change.

The recurring question is practical: when does adding capacity solve the problem, and when must the architecture or dependency contract change?

Twilio and its systems

Twilio is a Communications Platform as a Service (CPaaS) company that enables businesses to easily communicate with customers and others via text messages, emails, and calls.

The company is well-known for providing programmable communication tools on various communication channels using web service APIs. During his tenure, Mark Gilbert oversaw the Twilio Super Network and onboarding of phone numbers.

The Super Network connects Twilio’s software to carrier networks for communications such as voice and messaging. Twilio’s broader product portfolio also includes services such as email; do not assume every channel uses the same carrier path.