Inside Our Event-Driven Architecture Migration: Timeline, Budget, and Lessons

We built a custom dashboard that tracks the metrics that actually matter to our team. Vanity metrics like total page views were replaced with actionable signals: time-to-first-meaningful-interaction, error budget burn rate, and deployment frequency per team.

Accessibility improvements delivered unexpected business value. After making our checkout flow screen-reader compatible, we saw a 12% increase in completion rates across all users — the clearer interaction patterns helped everyone, not just assistive technology users.

Monitoring Setup

We stopped doing quarterly planning and switched to six-week cycles with two-week cooldowns. The cooldowns are for tech debt, experiments, and developer-chosen projects. Team satisfaction scores jumped 30% and, counterintuitively, feature delivery actually accelerated.

Post-mortems without action items are just storytelling. We implemented a strict follow-up process: every post-mortem produces at most three concrete action items, each assigned to a specific person with a deadline. Items that don’t get done within two sprints get escalated or explicitly deprioritized.

Our cost optimization effort started with the boring stuff: right-sizing instances, cleaning up orphaned resources, and switching to reserved capacity for predictable workloads. These unglamorous changes saved more than any architectural redesign would have.

Error handling deserves as much design attention as the happy path. We created a taxonomy of error types — retryable, user-fixable, operator-fixable, and fatal — and built standard handling patterns for each. Support tickets dropped by half because users finally got actionable error messages instead of generic 500 pages.

We started this project with a clear hypothesis: the existing approach was costing us more in maintenance time than the migration would cost upfront. Three months later, the data confirmed we were right — but the journey was far bumpier than expected.

What worked for us won’t work for everyone. Context matters enormously. But we hope sharing our experience saves someone else from repeating our more expensive mistakes.