Sai Sushanth Thakkalapally
Backend engineer with four years at Amazon building distributed systems and high-throughput services. I care about clean APIs, observable systems, and code the next person can actually read. Currently open to senior backend roles and select freelance work.
About
I'm a backend engineer who genuinely enjoys thinking about how systems fail — not pessimistically, but because if I can picture every way something breaks, I can build it so it doesn't. That was the job for four years at Amazon, across FinTech and Worldwide Returns.
Day to day that meant distributed services handling millions of requests, APIs other teams actually wanted to use, and the occasional 2am staring contest with a dashboard over a latency spike.
Outside of work I build to scratch my own itch. GoKV exists because I wanted to know how a database really works under the hood; ContractLens grew out of agreeing to one too many terms and conditions without ever reading them. These days I'm taking on select freelance work — backend architecture, API design, and systems consulting for teams that need things to scale reliably.
Working with
Hyderabad, India
Selected Work
04 projects
Storage engine
2026
An LSM-tree key-value store written from scratch in Go.
A persistent key-value store built to understand how modern databases work end to end: a write-ahead log for durability, a concurrent skip-list memtable, SSTables with bloom filters, and background compaction. Instrumented with Prometheus metrics — benchmarks on an M1 reach ~104K writes/s and ~4.5M memtable reads/s.
AI product
2026
AI contract analysis that extracts clauses, flags risks, and summarizes legal docs.
Upload a contract and get back the clauses that matter, the risks worth a second look, and a plain-language summary. Semantic search runs on Jina AI embeddings backed by a Pinecone vector store, with a FastAPI service handling PDF parsing and classification. Live in production.
Full-stack app
2026
A booking and management system for a farmhouse rental.
End-to-end booking platform built for a friend's farmhouse. Postgres exclusion constraints make double-booking impossible at the database level; role-based access separates owner and caretaker; a night-based availability calendar and per-event WhatsApp notifications round it out. Next.js on Vercel, Supabase for data and auth.
Backend service
2026
A dispute-resolution intelligence API built for a timed technical challenge.
A backend service for triaging and scoring payment disputes, designed and shipped under a strict time box. Built on Java 21 and Spring Boot with Supabase as the datastore, with clean REST contracts and a focus on readable, testable structure.
Experience
2024 — 2026
Amazon · FinTech · Worldwide Returns
Owned backend platforms across global tax compliance and returns, end-to-end from design through live-site operations. Shipped DAC7 / Inform Act compliance for 670K+ tax identities across 25+ countries, consolidated five partner endpoints into a single unified API handling 30K+ calls/month, led a zero-downtime JDK 17 migration across 90+ downstream clients, and built a multi-agent LangGraph + RAG incident-triage system that cut MTTR from ~45 to ~15 minutes. Two-time Reliability Award winner and OE Champion.
2022 — 2024
Amazon · FinTech
Built and operated backend services for tax and identity systems in Java and Go. Delivered a first-of-its-kind non-withholding compliance solution serving 100K+ payees across 75 workflows, and carried full on-call ownership for core services.
2022
Amazon · FinTech
Six-month internship building a proof-of-concept service that was adopted by the team and converted into a full-time offer.
What's next
Open to senior backend roles and select freelance projects — backend architecture, API design, and systems consulting. If you've got an interesting problem, my inbox is open.
saisushantht@gmail.com→