Mehbub

Platform and backend work: async job workers, subscription billing, real-time integrations, secure webhooks, and AWS/Turborepo/Bun tooling.

• Wrote async job workers with BullMQ + Redis using lease-lock heartbeat coordination and exponential backoff, bringing duplicate job executions to zero across restarts.
• Shipped a subscription state machine covering coupon-reserved renewals, scheduled plan changes, and cancellation-at-period-end, cutting billing escalations by ~40%.
• Wired up real-time market data via Fyers WebSocket with protobuf decoding and auto-reconnect, tracking 200+ symbols live and closing trade calls within <100ms of a target/stop-loss hit.
• Added timing-safe HMAC verification and a DB-backed replay guard to webhook ingestion, eliminating replay-based double-charges from Digio and KRA in production.
• Built coupon dispatch over AWS SES and WhatsApp (WATI) with row-level locking and DB check constraints, hitting 97%+ delivery success and ruling out duplicate sends.
• Set up a Bun + Turborepo monorepo with branch-based CI/CD and blue/green container switching, cutting deployment time by ~50% over the old shell-script workflow.

Greenfield product: Next.js UI, eKYC/e-sign integrations, Node/PostgreSQL APIs, AWS ECS, and Telegram notifications.

• Built a mutual fund platform from scratch using Next.js (TypeScript), Tailwind CSS, and ShadCN UI, delivering a modern and responsive user interface.
• Implemented smooth user onboarding, integrating eKYC and e-sign workflows with third-party vendors (CAMS, Digio), increasing user retention by 30%.
• Developed backend APIs using Node.js and PostgreSQL, ensuring secure and scalable data handling for portfolios, transactions, and fund search.
• Deployed the platform on AWS using ECS Fargate and S3 for storage, with a fully Dockerized deployment and automated scripts, improving deployment speed by 60%.
• Integrated a Telegram bot for automated notifications and user interactions, handling API rate-limiting and ensuring 99% uptime.

Open-source program coordination and code review across multiple repositories.

• Reviewed 60+ PRs and maintained project-wide coding standards across multiple repositories.
• Co-ordinated with contributors from diverse backgrounds, ensuring smooth collaboration in an asynchronous environment.