The Scene A CTO of a small FinTech company had scheduled a meeting with me along with senior folks from his engineering team. CTO : (shares screen) "Look at this. Every 1st and 15th of month - 9:00 to 9:30 PM - Our p99 latency spikes from 50 ms to 800 ms. After 4 mins - back to normal. Surprisingly, no 5xx errors, …

What happens when senior leadership ships a "soft launch" to production without architectural review - and why every architect needs a battle-tested framework for saying no. Background A product company - has been building software for a industry that operates in highly regulated environment for more than …

Background This is the fifth post in a series on AI-augmented software engineering across the disciplines that matter most for production grade enterprise systems. The earlier posts covered ground that's probably more familiar with software engineering fraternity: Three Fintech Architecture Post-Mortems The GC Summary …

Background An older post on this blog covered the technical details of this incident - the GC types, the flags, the before-and-after metrics. This post covers something different: the process of how the investigation ran, where it lost time, and which decisions (with more structured approach) would have changed. The …

Background My earlier article on AI augmented Fintech post-mortem review walked through an Oracle JSON storage problem: a payment transaction table stored as JSON, a query that needed to filter on a nested field, and the chain of fixes - that the team eventually needed. Out of curiosity - a reasonable question came …

Background In Part 1, we established that access patterns & not entities should drive your design. In Part 2, we fixed the database by replacing brittle three-table JOINs with a covering index, reducing P99 on the listing query. The schema was right. The index was right. The listing API itself was fast. And then it …

Background My old article compared Virtual Thread based implementations of Spring Core Reactor and JDK 21, building on the comparative analysis before it. Both articles measured the usual things - total processing time, memory footprint, GC pauses, CPU time - and both relied on the summary report generated by GCEasy. …

Background In the first part we established the foundational principle that separates systems which survive scale from systems that collapse under it - design for access patterns, not for entities. In this second part we double click on the database design of the User Profile system and try to understand its impact …

Background Architecture decisions rarely break at design time. They break a year later, under double the load, when an unwritten assumption proves false. I’ve seen this play out in synchronous coupling, storage models, and service splits - while architecting and designing FinTech platforms. That’s why I now run every …

Background This multi part series walks through the real architectural decisions and real mistakes behind designing a globally distributed KYC User Profile system - a system that should be capable of serving billions of users at 10M+ RPD with sub-500 ms P99 latency. It's mainly about weighing trade-offs and making …