Daniel J. - Senior Software Engineer

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Rzeszów, Poland

Experience

Feb 2020 - Present

5 years 9 months

Poland

Senior Software Engineer

Sii Poland

Built a microservices-based backend for Tracking system using Go (Golang), achieving sub-100ms response times.
Implemented gRPC for real-time communication between microservices, reducing latency by 40%.
Designed and optimized PostgreSQL schemas for transaction processing and user account management.
Set up Apache Kafka for event sourcing in a fraud detection system, enabling real-time transaction analysis.
Implemented serverless functions using AWS Lambda for processing transaction notifications.
Configured AWS RDS with read replicas for high availability and performance.
Designed and implemented a CI/CD pipeline using GitHub Actions, enabling frequent and reliable deployments.
Set up Prometheus and Grafana for monitoring transaction processing and system health.
Automated infrastructure provisioning using Terraform, reducing setup time by 60%.
Developed an event-driven notification system using Apache Kafka, processing 1M+ events daily.
Built a RESTful API for order management using Python Flask, ensuring seamless integration with mobile apps.
Implemented Redis for caching restaurant menus and order statuses, reducing database load.
Designed and optimized DynamoDB tables for storing real-time order data.
Set up RabbitMQ for asynchronous communication between order processing and delivery services.
Deployed the application on AWS ECS Fargate, ensuring scalability during peak hours.
Configured AWS SNS for sending push notifications to delivery partners and customers.
Implemented AWS Lambda for processing payment status updates and refunds.
Set up centralized logging using the ELK stack for troubleshooting and analytics.
Designed and implemented a disaster recovery plan using AWS Backup and cross-region replication.
Developed a microservices-based backend for a SaaS platform using Node.js and Express.js, ensuring scalability.
Implemented Redis for caching frequently accessed user data, reducing API response times.
Designed and optimized PostgreSQL schemas for storing user data and application settings.
Set up Apache Kafka for event-driven updates to user dashboards and notifications.
Deployed the application on Kubernetes (EKS) for high availability and scalability.
Configured AWS SNS for sending push notifications to users.
Implemented AWS Lambda for processing user uploads and transformations.
Set up centralized logging using the ELK stack for troubleshooting and analytics.
Designed and implemented a disaster recovery plan using AWS Backup and cross-region replication.
Configured Prometheus and Grafana for monitoring API performance and system health.

Oct 2014 - Dec 2019

5 years 3 months

Poland

Software Developer

Connected Digital Ltd

Developed backend microservices in Golang for image metadata management and user content feeds, leveraging Go’s high concurrency support.
Built a serverless image processing pipeline using AWS Lambda and S3 for a photo-sharing app.
Designed and optimized DynamoDB tables for storing media metadata and user interactions.
Set up Apache Kafka for event-driven updates to user feeds and notifications.
Deployed the application on Kubernetes (EKS) for high availability and scalability.
Configured AWS CloudFront for CDN to improve media delivery times for global users.
Implemented AWS Lambda for processing media uploads and transformations.
Set up centralized logging using the ELK stack for troubleshooting and analytics.
Built high-throughput APIs using Golang for real-time shipment tracking, replacing performance bottlenecks in legacy Python code.
Developed an event-driven architecture using AWS EventBridge and SQS for a logistics tracking system.
Built a RESTful API for shipment tracking using Python Flask, ensuring seamless integration with mobile apps.
Implemented Redis for caching frequently accessed shipment data, reducing database load.
Designed and optimized DynamoDB tables for storing real-time shipment data.
Set up RabbitMQ for asynchronous communication between shipment processing and tracking services.
Deployed the application on AWS ECS Fargate, ensuring scalability during peak hours.
Configured AWS SNS for sending push notifications to drivers and customers.
Implemented AWS Lambda for processing shipment status updates and notifications.
Set up centralized logging using the ELK stack for troubleshooting and analytics.
Designed and implemented a disaster recovery plan using AWS Backup and cross-region replication.

Sep 2011 - Oct 2014

3 years 2 months

Poland

Software Developer

University of Information Technology and Management

Developed a GraphQL API for a social media app, reducing over-fetching and improving client-side performance by 30%.
Implemented WebSocket-based real-time notifications for user interactions (likes, comments, messages).
Designed a microservices architecture using Go (Golang) for high-performance backend services.
Utilized Apache Kafka for event-driven updates to user feeds and notifications.
Set up MongoDB for storing user-generated content, ensuring scalability and flexibility.
Implemented OAuth2 and JWT-based authentication for secure user access.
Deployed the application on Kubernetes (EKS) for seamless scaling during peak traffic.
Configured Datadog for end-to-end observability, enabling quick troubleshooting of performance bottlenecks.
Developed a high-performance backend for a mobile gaming app using Go (Golang), achieving low-latency gameplay.
Implemented Redis for caching frequently accessed game data, reducing API response times.
Designed and optimized DynamoDB tables for storing real-time game data.
Set up Apache Kafka for event-driven updates to game state and player interactions.
Deployed the application on Kubernetes (EKS) for high availability and scalability.
Configured AWS CloudFront for CDN to improve game asset delivery times for global users.
Implemented AWS Lambda for processing in-game purchases and receipts.
Set up centralized logging using the ELK stack for troubleshooting and analytics.

Summary

Senior Backend Engineer with over 12 years of hands-on experience delivering robust backend systems and infrastructure for both startups and large-scale platforms.

Focused on building reliable, maintainable services using Go.

Skilled in architecting microservices and event-driven systems, with a strong emphasis on performance tuning and operational stability.

Experienced in DevOps practices including CI/CD pipelines, infrastructure provisioning, and cloud-native deployments on AWS.

Brings a systems-thinking mindset to backend engineering—designing solutions that are efficient, scalable, and easy to evolve.