# Rohit Rajan

> Tech lead and forward-deployed engineer in New Delhi, India, who also loves product work. Technology Manager & Senior Engineer at Sparklin Innovations Pvt. Ltd. 8+ years building and running production systems in TypeScript, Node.js, Python and PostgreSQL, plus RAG pipelines, embedding services and vector search. Leads a 14-person engineering team and still writes production code daily.

Looking for: tech lead and forward-deployed engineer roles where he shapes the product as much as the code.

Contact: write4rohitrajan@gmail.com · +91-7011673225 · https://www.linkedin.com/in/r-rajan4ever/ · https://github.com/rrajan94

## Key facts
- Leads a 14-person team that delivers 40% faster; owns architecture for consumer products serving 500k monthly users
- Mentors junior to senior engineers through weekly 1:1s and code-review pairing; runs end-to-end hiring
- Turns ambiguous product asks into engineering briefs with concrete options and latency targets
- 6 years of AWS in production (EC2, S3, ALB) at 99.95% uptime; Docker, Nginx, GitHub Actions

## Project walkthroughs
- [Personalized feed service](https://r4rohit.com/#projects): Node.js/TypeScript fan-out feed caching processed feeds in Redis for sub-50 ms responses. Fixed a same-day outage caused by unbounded queries and N+1 lookups; found two more services with the same issue before they became incidents.
- [Monolith decomposition](https://r4rohit.com/#projects): Legacy Node.js monolith split into domain-owned services for 3 products in 4 months, tenant-by-tenant cutover with reconciliation gates; legacy stayed the source of truth until the new path passed two full business cycles.
- [Hybrid infrastructure](https://r4rohit.com/#projects): Moved production compute from pure AWS to Hetzner bare metal + AWS behind Nginx, cutting cost 60 to 70 percent.
- [Timestamp-aware RAG](https://r4rohit.com/#projects): LangChain retrieval returning the exact passage plus context, graded by an eval harness on a held-out question set; Gemini 768-d embedding worker on FastAPI; FAISS to Qdrant migration with filtering inside HNSW. Retrieval accuracy up 35%.
- [opensre Elasticsearch log source](https://github.com/Tracer-Cloud/opensre): Former paid maintainer of a LangGraph-based SRE agent framework; shipped an Elasticsearch integration as a LangChain tool with 31 unit tests and raised auth/AWS module coverage from 0% to 100% with 34 tests.
- [WhatsApp Commitment Capture + TickDown](https://github.com/rrajan94/TickDown): Chrome extension reading WhatsApp Web, synced via Convex to a native Swift/SwiftUI macOS menu bar app with a Rust FFI bridge.
- [FR24 Weather Overlay](https://github.com/rrajan94/flightradar24-weather-overlay): Zero-dependency Manifest V3 Chrome extension that overlays live radar, lightning, storm cells and satellite imagery on Flightradar24.

## Experience
- Senior Engineer & Technology Manager, Sparklin Innovations Pvt. Ltd. (Dec 2019 – present)
- Paid Maintainer, Tracer-Cloud/opensre (past)
- Full Stack Web Developer, Kantag Solutions Pvt. Ltd. (Jul 2019 – Oct 2019)
- Web Developer (PHP), TEMZ (Oct 2017 – Jun 2019)
- Junior C# Developer, Caresoft Inc. (Feb 2017 – Jun 2017)
- B.E. Computer Science, SAM College of Engineering & Technology (2013 – 2017)

## Skills
TypeScript, JavaScript, Python, Node.js, FastAPI, Django, PostgreSQL, Redis/Valkey, MongoDB, Elasticsearch, Qdrant, FAISS, AWS, Hetzner, Docker, Nginx, GitHub Actions, LangChain, LangGraph, RAG, embeddings, LLM observability, React, Chrome extensions, Swift/SwiftUI

## Writing
- [We Stopped Thinking and Called It Productivity](https://medium.com/@r_rajan/we-stopped-thinking-and-called-it-productivity-2770ea7d7389) (Medium, April 2026)

## Optional
- [Resume (PDF)](https://r4rohit.com/Rohit_Rajan_Resume.pdf)