Open to opportunities

Sami Ullah

@samiullah

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Senior full-stack engineer improving mobile performance, APIs, and retention across iOS and Android.

United States

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What I'm looking for

I’m looking to lead mobile and full-stack builds with strong CI/CD, scalability, and product collaboration—where I can improve performance, reliability, and user retention with measurable results.

I’m a Senior Mobile & Full-Stack Engineer with 10+ years in software development across mobile and web platforms. I deliver measurable business impact by improving app performance and retention through mobile performance profiling and optimizations, including increasing engagement by 18%.

I build scalable REST APIs and GraphQL services with Express.js and NestJS, integrating secure authentication methods like JWT and OAuth. From Nexa Solutions to Puzzle HR, I’ve architected onboarding and API layers, reduced latency and auth errors, improved conversion and retention, and shipped faster releases with CI/CD-driven delivery—while partnering closely with product managers and designers using Agile/Scrum.

Experience

Work history, roles, and key accomplishments

Current

Senior Software Engineer

Current

Nexa Solutions

Feb 2024 - Present (2 years 3 months)

Architected a React Native onboarding flow with Redux and TypeScript, reducing time-to-first-action and increasing new-user conversion by 23% across iOS and Android. Built a NestJS GraphQL gateway and CI/CD pipelines, consolidating services, cutting client payloads by 48%, and reducing release cycle time to 6 hours.

React Native Redux TypeScript NestJS GraphQL JWT OAuth CI CD

Senior Software Engineer

Puzzle HR

Jul 2018 - Dec 2023 (5 years 5 months)

Designed offline-capable React Native HR features with TypeScript and MobX, increasing daily active users by 27% and session length by 22%. Implemented NestJS microservices with Prisma and GraphQL resolvers, reducing query latency by 55% and improving payroll API throughput while meeting compliance SLAs.

React Native TypeScript MobX NestJS Prisma GraphQL PostgreSQL CI CD JWT OAuth

Software Engineer

Cargo Express Freight

Jul 2016 - Jun 2018 (1 year 11 months)

Built a React.js logistics dashboard with Redux and TypeScript, improving dispatcher efficiency and reducing average resolution time by 38%. Developed Express.js APIs with MongoDB/Mongoose and optimized PostgreSQL data models, improving ETA accuracy by 21% and cutting report generation time by 72%.

React Redux TypeScript MongoDB Mongoose PostgreSQL REST APIs Docker

Software Engineer

FinEdge Labs

Jul 2015 - Jun 2016 (11 months)

Developed a React Native prototype and React.js admin portal integrating REST APIs, achieving 2 pilot clients and a 46% prototype adoption rate. Secured financial endpoints with Express.js, JWT authentication, and PostgreSQL/Sequelize schemas, reducing unauthorized access incidents by 54% and improving startup time and crash rates.

React Native React REST APIs JWT PostgreSQL Sequelize Jest Performance Profiling