The push channel, built end to end on serverless.

A multichannel platform is only as good as its weakest channel. A brand composing a campaign does not want to think about whether push behaves differently from email - it should schedule, target, send and report the same way.

Push has its own awkwardness underneath that expectation. It runs through vendor infrastructure you do not control, it is subject to delivery mechanics that differ between web and mobile, and a broadcast means a very large number of sends in a very short window rather than a steady trickle.

I built the web and mobile push notification service end to end on AWS Serverless: the broadcast path that fans a campaign out to its audience, and the webhook handling that brings delivery and engagement signals back, both sized for the burst shape that broadcast traffic actually has.

Push vendors do not agree with one another, so I engineered multi-vendor configuration handling to keep those differences out of the rest of the system, along with scheduled template fetching so campaign content stayed current without a person triggering it.

For the mobile side I wrote a React Native SDK for FCM push, so the channel worked inside the Shopify mobile app rather than only on the web.

I also built a Lambda authorizer covering the REST and Lambda surface, so authorisation was enforced in one place rather than reimplemented per endpoint, and a tool that automated domain verification for email broadcast - a step that had been manual, slow and easy to get wrong during onboarding.

This was infrastructure work where the interesting failures are all operational rather than logical. I would build the delivery observability first next time: when a broadcast underperforms you want to know within minutes whether it was the audience, the vendor or the payload, and that is much harder to add afterwards.

The multi-vendor abstraction was also drawn after the second vendor rather than in anticipation of it, which is the right instinct but meant one migration that a slightly later abstraction would have avoided.