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maruf billah

@marufbillah

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Lead Software Engineer at Echologyx Ltd who shipped 1,500+ A/B experiments and built a double-entry wallet.

Bangladesh

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At Echologyx Ltd, I lead 10 engineers and built ABTestLab, an open-source A/B testing CLI now used company-wide. For a global luxury group, I shipped 1,500+ experiments across 20+ e-commerce brands.

On eHRMS, I contributed heavily to the React front end and delivered the KPI module end to end, including its UI, API, permissions, and dashboards. I also added Microsoft Entra ID SSO and partner APIs for leave data.

For a travel and hospitality group, I designed and built the API for a nine-vertical travel super-app, including a double-entry wallet and crash-recoverable checkout. Earlier, at Nexkraft Limited, I developed Android applications in Java, including a transport-management app for BRAC.

Experience

Work history, roles, and key accomplishments

Current

Lead Full-Stack Engineer

Current

Travel and hospitality group (confidential)

Jan 2024 - Present (2 years 9 months)

Designed and built the API for a 9-vertical travel super-app as a NestJS modular monolith with 70 data models and ~236 endpoints. Built a double-entry ledger and wallet with idempotent checkout saga.

NestJS PostgreSQL React EC2 Docker

Current

Lead Full-Stack Engineer

Current

Echologyx Ltd

Jan 2023 - Present (3 years 9 months)

Joint top contributor to the React front end of the company's employee-management platform, delivering the KPI module end to end and adding Microsoft Entra ID SSO. Built a serverless API on AWS Lambda with CI/CD.

React TypeScript Redux Saga MUI NestJS TypeORM PostgreSQL AWS Lambda S3 GitHub Actions

Current

Lead Software Engineer

Current

Echologyx Ltd

Jan 2022 - Present (4 years 9 months)

Lead a team of 10 engineers, handling technical design, code review, estimates, mentoring, and client communication. Built ABTestLab and ABTestPilot, the team's standard A/B testing tooling.

JavaScript TypeScript React Next.js NodeJS NestJS PostgreSQL AWS Azure CI CD A B Testing VWO AB Tasty Dynamic Yield Kameleoon GitHub Actions

Full-Stack Engineer

Echologyx Ltd

Jan 2025 - Dec 2026 (1 year 11 months)

Built a QA and performance-analytics platform almost single-handedly, including a NestJS API with 59 data models and a React 19 front end. Engineered a Jira-to-PostgreSQL sync engine and a configurable KPI system.

NestJS Prisma PostgreSQL Socket.IO React TanStack EC2 Lambda GitHub Actions

Front-End Engineer

Echologyx Ltd

Jan 2022 - Dec 2025 (3 years 11 months)

Built and shipped 1,500+ A/B/n experiments across 20+ luxury e-commerce brands, working daily with the client's optimisation team in France. Delivered product finders, size guides, checkout redesigns, and animated campaigns.

JavaScript SCSS GSAP VWO AB Tasty Dynamic Yield Kameleoon GitHub Actions