Saifullah Shahen
AI-Focused Software Engineer
Specialized in architecting production-ready systems using Python (Django, FastAPI) and modern frontends (Next.js, Vue.js). Currently focused on the end-to-end integration of AI-driven logic and automated data workflows into scalable web applications. Expert in clean architecture and structured data modeling, bridging the gap between sophisticated data science and robust software delivery.
About
Backend engineer with 2+ years of experience building and maintaining production systems. Worked on real-world platforms including recruitment and pharmaceutical ordering systems, focusing on scalable architecture, performance, and reliability. Take ownership of backend components from design to deployment, while collaborating closely with product and frontend teams.
How I contribute
- End-to-end features: scalable APIs/schemas + integrated frontends (Nextjs, Vuejs)
- Designed REST APIs, relational database schemas, and backend architecture
- Improved system performance using query optimization, indexing, caching, and background tasks
- Implemented RBAC, permission systems, and workflow-driven backend logic
- Owned backend features end-to-end, from design and implementation to deployment and maintenance
- Contributed across the stack when needed using Next.js and Vue.js
Open to Working Student/Junior Backend or Full-Stack Software developer roles in Germany
Skills
Backend
Databases & Search
DevOps
Frontend (collaboration)
Experience
- Led backend development for multiple production-grade web platforms using Django and Django REST Framework
- Improved API response time by approximately 30–45% through PostgreSQL query optimization and indexing strategies
- Reduced heavy synchronous processing time by 50% by introducing Celery-based background task handling
- Implemented Redis caching and search patterns, reducing repeated database hits and improving lookup speed significantly
- Integrated Elasticsearch for advanced search, improving search accuracy and filtering efficiency for large datasets
- Designed and maintained scalable relational database schemas supporting complex business workflows
- Implemented role-based access control (RBAC) and multi-stage approval/review systems
- Contributed to upgrading and refactoring core ordering modules, improving maintainability and reducing technical debt
- Participated in legacy production data migration and ensured financial/data consistency validation
- Improved system reliability by adding structured error handling and backend test cases
- Took ownership of sprint-based delivery cycles (weekly), ensuring feature completion aligned with roadmap
- Led sprint planning discussions and actively participated in PR reviews and architecture decisions
- Contributed to product brainstorming sessions, proposing feature enhancements and long-term scalability improvements
- Guided and supported junior developers in backend architecture and implementation practices
Projects
An AI-assisted online learning platform designed for Bangladeshi students from elementary to high school. The platform combines structured lessons, practice exercises, animated explanatory videos, and real tutor-led classes. It also includes parental access to monitor student progress weekly and monthly. The system is designed to make education more accessible, engaging, and scalable.
Duration: Feb 2026 – Present
Role: Full-Stack Developer, System Architect & Product Owner (personal project)
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- Defined product vision and created user stories for students, tutors, and parents
- Designed system architecture for scalable course delivery, progress tracking, and tutor workflows
- Researched and designed AI-assisted learning support using structured practice and explanatory video content
- Built frontend using Next.js, TypeScript, and shadcn/ui with modular, scalable component architecture
- Developed backend using Django and Django REST Framework with clean API boundaries
- Designed relational database schema for users, courses, lessons, tutor sessions, and progress tracking
- Implemented parent access model to monitor children's weekly and monthly learning progress
- Designed tutor workflow system where real tutors conduct classes based on structured learning plans
- Deployed early production version and configured domain, hosting, and environment
- Addresses real educational challenges in Bangladesh with scalable digital learning infrastructure
- Demonstrates full product ownership from idea, user research, architecture, and implementation
- Designed to support large-scale student learning with AI-assisted educational workflows
- Improves transparency and trust through parental progress tracking
An end-to-end recruitment platform where HR teams manage the full hiring pipeline: job posts, candidate screening, multi-stage reviews, scoring, and decisions. HR can assign office staff as reviewers, run an initial screening test with auto-evaluation, and onboard staff via Excel with permission control.
Duration: Apr 2023 – Dec 2024
Role: Backend Team Lead (built from scratch, led delivery)
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- Started the backend from scratch and designed the core relational database schema
- Defined API boundaries and review workflow states (screening → review → shortlist/reject) with consistent rules
- Implemented RBAC + granular permissions for owner/admin/reviewer roles
- Built candidate scoring and filtering so HR/reviewers can rank and shortlist efficiently
- Implemented Excel bulk onboarding to create staff accounts and assign permissions
- Used Redis-based search patterns for fast candidate/staff lookup
- Integrated Twilio/SMS and ensured email notifications for candidate updates
- Led sprint planning, task delegation, PR reviews/merges, and weekly client demos; mentored 2–4 backend devs under pressure
- Reduced manual coordination by centralizing hiring stages, reviews, and decisions in one system
- Enabled scalable team hiring by allowing HR to assign reviewers and compare scores across reviewers
- Improved onboarding speed via Excel import and permission templates
A high-traffic B2B pharmaceutical platform in Bangladesh with e-commerce, delivery tracking, and operational workflows. The main challenge: unify three different order sources into one ordering workflow and migrate legacy orders while keeping finance dashboards consistent.
Duration: May 2024 – Mar 2025
Role: Backend Lead
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- Led Order V2 upgrade to unify three order types into one consistent flow
- Implemented ordering logic across multiple sources (deliveryman orders, call orders, website orders)
- Planned and executed legacy data migration for orders and related entities
- Synced order updates with delivery tracking data to keep operations aligned
- Worked closely with finance-related logic to keep dashboard numbers consistent after migration
- Integrated SMS notifications for key order events and multi-person order handling
- Unified order handling reduced downstream complexity and duplicated logic
- Migration preserved business continuity while modernizing core ordering workflows
- Improved reliability of finance/operations views by keeping order + delivery data in sync
A B2C pharmaceutical e-commerce platform (shop to end-customer), built in parallel to the broader pharma ecosystem. The project was discontinued due to budget constraints.
Duration: Dec 2022 – Jan 2023
Role: Backend Developer (early-stage build)
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- Implemented core backend APIs required for B2C shopping flows
- Added Redis-based search for fast product lookup
- Integrated SMS notifications for key customer events
- Supported Dockerized environment and collaborated with frontend on API contracts
- Enabled a B2C channel foundation reusing pharma domain knowledge and workflows
- Provided a scalable backend base (even though the product stopped early)
A B2B furniture platform serving Nordic countries. I contributed on a sprint basis, implementing backend features assigned by the team lead.
Duration: Jan 2024 – Jun 2024
Role: Backend Developer (sprint delivery)
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- Implemented API endpoints within sprint scope for business workflows
- Improved performance by optimizing slow PostgreSQL queries
- Collaborated in sprint planning/reviews and aligned changes with team standards
- Delivered features predictably in sprints for an international B2B product
- Improved responsiveness in critical paths via query optimization
Education
Research / Publication
Contact
If you’re hiring for backend roles (Werkstudent / Junior), I’m happy to share details or walk through my projects.