Ashwin Gopalsamy
Hey! I'm Ashwin. I build the infrastructure behind global payments.
I work from home; on a countryside region wrapped in coconut groves, close enough to the Western Ghats that the weather has opinions.
I'm a Staff Engineer at Pismo, a Visa company working on sub-second high-throughput distributed systems. Previously, built core-banking stuff.
This fall I start my Masters in AI at UT Austin alongside my work.
Off the clock, I'm happiest around good machinery and cars, or absorbed in technology, anthropology, old history, and long-form work of almost any kind. Here's the library of stuff I love, photos I take and cafes I try and more.
— latest notes
- Designing Rate Limiters for Payment SystemsWhy payment rate limits can't treat false rejects like a normal API, and how to design for authorization ingress.
- Understanding ISO 8583 Bitmap ParsingHow ISO 8583 bitmaps declare which data elements are present — and how to parse them at authorization ingress.
- Go Error Wrapping PatternsThe fmt.Errorf %w pattern and the nuances of wrapping, unwrapping, and adding context to Go errors.
— selected craft
- UUIDCheckZero-dependency Go utility for validating and identifying UUID formats across RFC 4122 and RFC 9562 versions.
- Claude Code ThemeVS Code theme system with 12 variants, programmatic compilation pipeline, and WCAG-validated contrast ratios. Published on the Marketplace.
- Pismo ZonesTimezone tool used daily across Pismo's distributed offices
— contact
Staff Software EngineerVisa (Pismo)2025 - present
Previously
- Core-BankingSolaris SE2022 - 2025
- IT ServicesHexaware Technologies2021 - 2022
- Cloud, open sourceMicrosoft4 months
Working on payments infrastructure, AI, or something else entirely?
— connect
Pollachi, Tamil Nadu
Map couldn’t load — coordinates below
10.657°N 76.956°E
— a line worth keeping
"A good plan violently executed now is better than a perfect plan executed next week."