Headline

Senior Backend Engineer | Node.js, Python, AWS, Cloudflare | Scaling APIs to 4M+ Requests/Day | Payments (Stripe/Razorpay) & API Performance

About

I build and run backend systems for SaaS at scale. At Whydonate, a European fundraising platform, I'm the backend engineer, responsible for infrastructure that handles 4M+ API requests/day and processes significant monthly payment volume. The problems I spend my time on: API performance (cut response times 70% on a system serving 60k+ users), payment infrastructure (Stripe, Razorpay, webhooks, failed-payment recovery), and scaling data systems (PostgreSQL, Redis, Elasticsearch, AWS, Cloudflare Workers). Lately, a lot of production RAG and LLM API work too

Location

Bengaluru

AI stack

claude code

codex

grok

n8n

openai

OpenRouter

Work experience

Senior Backend Developer at Whydonate: Crowdfunding & Fundraising Platform, Oct 2024 - Present · 1 yr 11 mos, India, • Re-architected the authentication system, fixing long-standing reliability and security issues • Cut database CPU usage to a steady ~10% through query optimization, indexing, memory tuning, and read replicas, eliminating performance degradation at peak load • Self-hosted Typesense search infrastructure with 99.9% uptime and zero data loss, including automated backfill triggers for recovery • Built AI integrations into the core product (LLM APIs, retrieval pipelines) • Platform monthly turnover grew ~35x during this period, backend reliability, payment infrastructure, and restored checkout were among the contributing factors • Established logging, monitoring, and alerting across services, cutting time-to-detection for production issue

Backend Developer at Whydonate: Crowdfunding & Fundraising Platform, Oct 2022 - Oct 2024 · 2 yrs 1 mo, Bengaluru, • Achieved a 70% reduction in API response time, driving a 20% increase in user engagement • Scaled backend infrastructure to support 60K+ users • Developed a Python ETL pipeline with PostgreSQL and Elasticsearch for real-time data synchronization • Implemented security hardening across backend services • Built and optimized scheduled jobs (cron) for core backend processes

Software Developer at Seezil Tech - A revolution brewing in your Tea Cup., Apr 2021 - Sep 2021 · 6 mos, Guwahati, Assam, India

Software Developer at Blue Bell, Jan 2020 - Mar 2021 · 1 yr 3 mos, Guwahati, Assam, India

Education

Bachelor of Technology (B.Tech.), Computer Science and Engineering, Assam Don Bosco University, Guwahati

Higher Secondary, Science, Tinsukia English Academy

Public links

github: https://github.com/sarmaasis