Engineering notes

Things we have learned, written down

Practical notes from real engagements, including the mistakes and the parts that surprised us.

All topics Engineering4 AI & Data2 Business Technology3 Security2 Company1

Engineering3 min read

Idempotency is the difference between a payment system and a payment problem

Retries are not an edge case, they are the normal operating condition of any distributed system. Here is the design that keeps a duplicate request from becoming a duplicate charge.

#Payments#Distributed Systems#API Design

Arjun Nair · 31 Aug 2026

Security2 min read

Rate limiting is a product decision before it is a technical one

Where you set the limits determines whether you stop attackers or annoy customers. The technical part is the easy part.

#API Design#Security#Rate Limiting

Ishita Roy · 6 Jul 2026