Backend & APIs
Getting the service right comes before getting it fast. I care about clean contracts and knowing how things break before they do.
- Go
- Node.js / TypeScript
- Python
- Protocol Buffers
- REST APIs
- Microservices
I'm Sarthak Agrawal. Backend-heavy, full-stack — I build LLM tooling, real-time pipelines, and the infrastructure that keeps AI features dependable in production. I also ship the products that run on top.
// how i think
Most of the job isn't the code that works first try. It's the request that times out, the queue that backs up, the dependency that goes down. That's what I build for.
// selected work
Four projects from my day jobs — what the problem was, what I built, and what changed.
pytorch · webassembly · webgpu · browser
A small GPT (~0.8M params, byte-level) written from scratch in three layers — a PyTorch reference, a hand-derived C++/WASM implementation, and a full WebGPU training loop — running entirely in a browser tab. Every layer's backward pass was finite-difference checked before being trusted.
embeddings · vector search · ranking
A home feed that actually learns what you like. Content gets embedded with BERT, ranked by similarity in Milvus, and the user vector keeps updating from live events. Engagement went up 40%.
streaming · protobuf · fan-out
The streaming backbone of a fintech social app. Go services push live market data through Kafka to clients in real time — and it held up while daily users went from 15k to 200k.
retrieval · openai · moderation
A set of RAG chatbots — support, learning, assistant — built on OpenAI APIs and grounded in real product docs. The support one cut human replies by 90%.
temporal · reliability · go
Financial planning can't run on workflows that quietly break. Moving them to Temporal killed 90% of the random failures and gave the team back about three hours a day.
// open source
A few favourites, pulled out of 100-plus public repos.
Hand it a topic and it writes the script, makes the images, records a voiceover and renders the video.
Stitches a few video feeds into one panorama using SIFT feature matching and homography.
I loaded 10M rows into ClickHouse and Elasticsearch three ways each, just to see what’s actually faster.
Caches a subreddit and gives you AI summaries of it, with links back to the posts they came from.
A status-page API built for multiple tenants — roles, auth, and live updates over websockets.
The backend for a dating app: matching, chat, notifications and cron jobs, on Redis and Prisma.
// expertise
From the API down to storage, plus the AI parts that sit on top.
Getting the service right comes before getting it fast. I care about clean contracts and knowing how things break before they do.
Streaming pipelines, durable workflows, real-time delivery — the parts that decide whether a product survives getting popular.
Personalized feeds, retrieval pipelines, agents. The goal is AI that holds up in production, not just in a demo.
Pick storage for how the data actually gets read and written. Then cache the slow paths until they stop being slow.
// trajectory
A short version. The longer story lives on the about page.
Feb 2025 — Present
Backend services and reliability infrastructure for a wealth-management platform — financial planning, durable workflows, and the systems they run on.
Jan 2022 — Jan 2025
Backend and data infrastructure for a fast-growing fintech social product — real-time market data, personalized feeds, and the AI systems layered on top.