Bablu Kumar Singh
Backend Developer & AI/Agentic Engineer
Full stack developer working across backend, frontend, and, these days, a fair amount of generative and agentic AI. Most of the day-to-day is Node.js, Express, PostgreSQL, and MongoDB: schema design, API architecture, and whatever shows up once real traffic hits. Built ROI Spectrum, a multi-tenant SaaS platform with Stripe subscriptions and audit logging, shipped 200+ REST APIs along the way, and cut average query response times by about 30% through a database indexing pass. Redis and RabbitMQ handle caching and background jobs; React, Next.js, and React Native cover the frontend and mobile side. On the AI side, built and published AgentCore, a TypeScript SDK for multi-provider LLM agents with memory and guardrails, and is now building Memorybook, a self-hosted hybrid-RAG app.
Development Philosophy
Readable now, debuggable later
I'd rather spend an extra ten minutes naming things clearly than leave a mess for whoever debugs this next — often me, six months on.
Assume it fails somewhere
Retry logic, input validation, a plan for the webhook that doesn't arrive — not glamorous, but it's what keeps a SaaS platform running unattended.
Check before you optimize
An EXPLAIN ANALYZE output is worth more than a guess. I've been wrong about which query was slow often enough to stop assuming.
Career Journey
Full Stack Developer @ Dextrous Infosolution
Mar 2026 – Present- Full Stack Developer, working across backend and frontend.
Full Stack Developer @ X-Strategy Services LLP
Sept 2024 – Mar 2026- Took end-to-end ownership of application development across backend systems and frontend interfaces, ensuring scalable architecture and timely delivery.
- Architected and developed ROI Spectrum, a multi-tenant SaaS platform with subscription workflows, service tracking, audit logs, and user-facing dashboards.
- Implemented payment gateway integrations with subscription lifecycle handling, webhook automation, and billing workflows.
- Designed and delivered 200+ RESTful APIs with validation, versioning, and error handling across production systems.
- Optimized APIs and database queries using indexing and aggregation strategies, reducing response time by 30%.
- Implemented role-based access control (RBAC) systems with hierarchical permissions across multiple user roles.
Daily DSA Journey
A running habit more than a project — mostly medium-difficulty problems, the kind that show up in interviews and, every so often, in an actual query-optimization problem.
Academic Foundations
Master of Computer Applications (MCA)
2022 – 2024A.N. College, Patna | 8.3 CGPA – Rank #1
B.Sc. Mathematics
2019 – 2022S.G.D.M. College, Patna
Current Focus & Learning Roadmap
Generative & Agentic AI
Shipped AgentCore, a TypeScript SDK for multi-provider AI agents with memory and guardrails, and currently building Memorybook, a self-hosted hybrid-RAG app — more on the Agentic AI page.
System Design Patterns
Reading up on what happens once a system has more than one service talking to itself — eventual consistency, CQRS, the usual CAP theorem trade-offs.
Mobile Apps (React Native)
The newest area. Expo, local SQLite storage, and figuring out what "offline-first" actually requires once sync conflicts show up.
Rust & WebAssembly
Not urgent, but curious about writing something fast and memory-safe outside the usual Node.js comfort zone.
Beyond the IDE
Outside of APIs and query plans: chess puzzles, history books, and more opinions about hardware than anyone's asked for.