From microservices to monolith

Hello, 👋

This is the last issue in 2025. We'll take a short break over Christmas to recharge and will be back on the first Monday in January. Thank you so much for your support and your lovely feedback. I have a lot to go through from the survey and figure out what to bring into the newsletter.

Lastly, I'd like to ask you to share the newsletter with your tech friends and colleagues. It helps heaps.

Twilio's migration from microservices to monolith
14 minutes by Alexandra Noonan

Twilio Segment moved from microservices to a monolithic architecture for their customer data pipeline. Their microservice setup initially solved performance issues by isolating destinations from each other. However, managing over 140 separate services became overwhelming. The team spent most of their time maintaining systems rather than developing features. They consolidated everything into a single service and repository, which dramatically improved developer productivity and reduced operational overhead.

Bring Order to Engineering Chaos
sponsored by Zencoder

Zenflow turns shipping software into a structured, spec-driven workflow: clear requirements, AI-generated plans, verification and multi-agent execution with parallel execution that keeps teams aligned from start to finish. If you’re tired of rework and endless Slack threads, Zenflow is the operating system your team has been missing.

Full unicode search at 50× ICU speed with AVX‑512
29 minutes by Ash Vardanian

ICU gets Unicode right but it's costly. In this post Ash shows a different approach. He developed a fast UTF-8 search library that dramatically speeds up Unicode text processing. Instead of using the slow traditional approach of converting everything to lowercase first it finds "fold-safe windows" in search patterns and uses specialized SIMD kernels for different script families like Latin, Cyrillic, and Greek.

Engineering dogmas it's time to retire
7 minutes by Anton Zaides

Anton covers five common software engineering practices and why he thinks they are worth reconsidering. According to him using external packages isn't always better since dependencies can break unexpectedly and create security risks. Mandatory code reviews slow down development, and trusted engineers should be able to merge their own code. Traditional sprints with strict timelines can drain creativity from development work. Feature flags often multiply out of control and make codebases harder to manage. Finally, comments in code are actually helpful and can save future developers time.

Modernizing Reddit's comment backend infrastructure
8 minutes by Katie Shannon

Reddit migrated their comment system from a legacy Python service to a modern Go microservice. Comments are Reddit's largest model with the highest write volume, making it a challenging first migration. The team used tap compare testing for safe migration, creating separate sister databases to test writes without corrupting production data. The migration cut latency in half and completed with no user disruption.

What does a database for SSDs look like?
8 minutes by Marc Brooker

Marc explores how databases should be redesigned for modern SSDs, cloud infrastructure, and global applications. He explains why old design choices made for slow disks no longer fit today’s fast storage and networks. Marc suggests keeping relational databases and SQL, but moving durability, scaling, and recovery to distributed systems optimized for SSDs, low latency, and high availability.

And the most popular article from the last issue was:

• 21 lessons from 14 years at Google

Happy holidays!
Jakub