Lukasz Ren - Software Engineer

Q: Where is Lukasz based?

Lukasz is based in Popowo, Poland .

Q: What languages does Lukasz speak?

Lukasz speaks the following languages: English (Advanced), Vietnamese (Intermediate) .

Q: How many years of experience does Lukasz have?

Lukasz has at least 9 years of experience. During this time, Lukasz has worked in at least 4 different roles and for 4 different companies . The average length of individual experience is 2 years and 3 months . Note that Lukasz may not have shared all experience and actually has more experience.

Q: What is Lukasz's latest experience?

Lukasz's most recent position is Software Engineer at SoftTeco .

Q: What companies has Lukasz worked for in recent years?

In recent years, Lukasz has worked for SoftTeco and WarmElsa .

Q: Which industries is Lukasz most experienced in?

Lukasz is most experienced in industries like Information Technology (IT) and Banking and Finance .

Q: Which business areas is Lukasz most experienced in?

Lukasz is most experienced in business areas like Information Technology (IT) , Product Development , and Operations .

Q: Which industries has Lukasz worked in recently?

Lukasz has recently worked in industries like Information Technology (IT) and Banking and Finance .

Q: Which business areas has Lukasz worked in recently?

Lukasz has recently worked in business areas like Information Technology (IT) , Operations , and Product Development .

Recommended expert

Popowo, Poland

Experience

Jan 2024 - Jun 2025

1 year 6 months

Software Engineer

SoftTeco

Built Java Spring Boot microservices for real-time banking transactions and trading operations
Applied CQRS with MediatR-style patterns and event sourcing using EventStoreDB for consistency and auditability
Designed serverless, event-driven workflows using AWS Lambda, API Gateway, SQS/SNS, and DynamoDB, monitored via Datadog & CloudWatch
Developed REST, gRPC, and GraphQL endpoints with Spring Boot, handling high-concurrency transaction and reporting APIs
Implemented Spring AOP and custom annotations for cross-cutting concerns like logging, metrics, and auditing
Optimized PostgreSQL and Redis queries for low-latency access to transaction data; applied caching and indexing strategies
Integrated JWT, OAuth2, and AWS Cognito for secure RBAC-based authentication and authorization
Refactored Angular frontend using Reactive Forms, FormGroup/FormControl, patchValue/setValue, validators, and NgRx store with selectors, actions, and effects
Applied RxJS operators (combineLatest, pipe, map, filter) for reactive UI updates
Built background jobs and async processing pipelines with Spring Batch and Quartz for trade settlement and reporting
Deployed microservices to AWS ECS with Docker and Terraform, implementing blue/green deployments, auto-scaling, and high availability
Configured observability pipelines with ELK Stack, Datadog, and CloudWatch to monitor latency, errors, and throughput
Automated CI/CD pipelines with GitHub Actions and Jenkins, including linting, unit/integration tests, container builds, and rolling deployments
Wrote unit, integration, and E2E tests with JUnit, Mockito, and Karma/Jasmine, following TDD practices
Mentored junior developers, conducted code reviews, and collaborated across teams on API design and system architecture

Sep 2019 - Dec 2023

4 years 4 months

Full Stack Engineer

WarmElsa

Developed modern, responsive UIs using Angular (RxJS, NgRx) and TypeScript, integrated with APIs and third-party services
Built reusable Angular component libraries with Angular Material and SCSS, improving design consistency across apps
Designed and implemented RESTful and GraphQL APIs with Java (Spring Boot), serving high-traffic web applications
Integrated external services such as Stripe, Salesforce, and Twilio, enabling payments, CRM synchronization, and SMS/email notifications
Implemented AI-driven features like document summarization and semantic search using Java-based AI libraries and APIs
Built background job pipelines with Java (Spring Batch/Quartz) and Redis for asynchronous data processing and reporting
Deployed and scaled microservices on AWS ECS with Docker and Terraform, ensuring fault tolerance and auto-healing clusters
Implemented monitoring and logging with Datadog, ELK Stack, and AWS CloudWatch, enabling proactive incident response
Automated CI/CD workflows with GitHub Actions and Jenkins, adding linting, tests, and blue/green deployments
Optimized database queries in PostgreSQL using indexing and caching, reducing latency
Improved frontend performance through Angular lazy loading, route-based code splitting, and Lighthouse audits, boosting SEO rankings
Led code reviews and introduced TDD with JUnit, Mockito, and Jest, achieving 85%+ test coverage
Mentored junior developers and contributed to knowledge-sharing sessions, improving team delivery velocity

Jul 2017 - Aug 2019

2 years 2 months

Midle-level Full Stack Developer

Timspark

Built and maintained Angular frontends with NgRx and RxJS for complex state management
Developed backend services with Java (Spring Boot), exposing RESTful APIs
Implemented WebSockets and real-time APIs for chat, notifications, and collaborative tools
Designed PostgreSQL schemas with Hibernate/JPA ORM, optimizing queries for high-volume transactional workloads
Integrated OAuth2, JWT, and SAML authentication flows, enhancing platform security and compliance
Applied MFA and PKI encryption to sensitive data workflows, strengthening data protection
Containerized applications with Docker and deployed them in Kubernetes clusters, enabling horizontal scaling
Automated CI/CD pipelines with Jenkins and GitLab CI, including unit tests, integration tests, and container builds
Introduced Sentry and Prometheus for performance monitoring and error tracking
Integrated social media APIs (Facebook, LinkedIn) for analytics aggregation dashboards
Implemented blockchain-related features including Solidity smart contracts and wallet integrations (MetaMask, WalletConnect)
Developed mobile and desktop apps with Ionic and Electron, extending platform reach
Adopted TDD with JUnit, Mockito, and Jest, reducing regression bugs by 30%
Collaborated with Agile teams using Jira, Scrum ceremonies, and sprint planning, contributing to continuous delivery

Jun 2016 - Jun 2018

2 years 1 month

Back End Developer

uCloud

Developed backend services using Java (Spring Boot), with PostgreSQL and MySQL as primary databases
Built and maintained REST APIs for internal services and external client integrations
Containerized services with Docker and deployed to AWS Elastic Beanstalk
Collaborated with frontend teams to integrate APIs into interactive dashboards
Participated in Agile sprints, contributing to code reviews, testing, and documentation

Industries Experience

See where this freelancer has spent most of their professional time. Longer bars indicate deeper hands-on experience, while shorter ones reflect targeted or project-based work.

Experienced in Information Technology (7.5 years) and Banking and Finance (1.5 years).

Information Technology

Banking and Finance

Business Areas Experience

The graph below provides a cumulative view of the freelancer's experience across multiple business areas, calculated from completed and active engagements. It highlights the areas where the freelancer has most frequently contributed to planning, execution, and delivery of business outcomes.

Experienced in Information Technology (9 years), Product Development (7.5 years), and Operations (4.5 years).

Information Technology

Product Development

Operations

Summary

Full Stack Engineer with 8+ years of experience building cloud-native, secure, and scalable applications. Skilled in Java (Spring Boot), Angular, TypeScript, microservices, and real-time/event-driven systems. Experienced in AWS, CI/CD, observability, and TDD. Strong in performance optimization, domain-driven design, and mentoring agile teams.

Skills

Languages:

Java, Typescript, Javascript (Es6+), Sql, Html5, Css3, Scss, Bash, Yaml, Json

Backend Frameworks & Libraries:

Spring Boot, Spring Cloud, Spring Mvc, Hibernate/jpa, Quartz, Kafka, Jms, Amqp, Rest, Graphql, Soap, Websockets, Microservices, Event-driven Systems, Spring Aop, Custom Annotations

Frontend Frameworks & Libraries:

Angular, Angularjs, Angular Material, Ngrx, Rxjs, Reactive Forms, Custom Pipes, Custom Directives, Scss, Tailwind Css, Material Ui

Databases:

Postgresql, Mysql, Mariadb, Mongodb, Redis, Dynamodb, Orm/odm (Hibernate/jpa, Prisma, Sequelize, Mongoose)

Cloud & Devops:

Aws (Lambda, Ecs, Ec2, S3, Rds, Api Gateway, Cloudfront, Cloudwatch), Gcp (Cloud Functions, Pub/sub, Firestore, Bigquery), Azure Functions, Docker, Kubernetes, Terraform, Github Actions, Gitlab Ci/cd, Jenkins, Ci/cd Pipelines, Blue/green Deployments

Testing & Quality:

Junit, Mockito, Jest, Karma, Jasmine, Cypress, Playwright, Selenium, Postman, Swagger/openapi, Tdd/bdd, Sonarqube, Eslint, Prettier

Tools & Others:

Git, Github, Gitlab, Bitbucket, Jira, Confluence, Figma, Adobe Xd, Api Integrations (Stripe, Paypal, Twilio, Sendgrid, Firebase Auth, Auth0, Okta), Oauth2, Jwt, Sso, Agile/scrum, Domain-driven Design, System Architecture Design

Languages

English

Advanced

Vietnamese

Intermediate

Education

Oct 2012 - Jun 2016

Saigon International University

Bachelor’s degree · Computer Science · Ho Chi Minh City, Viet Nam

Profile

Created

November 2025

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Frequently asked questions

Do you have questions? Here you can find further information.

Where is Lukasz based?

Lukasz is based in Popowo, Poland.

What languages does Lukasz speak?

Lukasz speaks the following languages: English (Advanced), Vietnamese (Intermediate).

How many years of experience does Lukasz have?

Lukasz has at least 9 years of experience. During this time, Lukasz has worked in at least 4 different roles and for 4 different companies. The average length of individual experience is 2 years and 3 months. Note that Lukasz may not have shared all experience and actually has more experience.

What roles would Lukasz be best suited for?

Based on recent experience, Lukasz would be well-suited for roles such as: Software Engineer, Full Stack Engineer, Midle-level Full Stack Developer.

What is Lukasz's latest experience?

Lukasz's most recent position is Software Engineer at SoftTeco.

What companies has Lukasz worked for in recent years?

In recent years, Lukasz has worked for SoftTeco and WarmElsa.

Which industries is Lukasz most experienced in?

Lukasz is most experienced in industries like Information Technology (IT) and Banking and Finance.

Which business areas is Lukasz most experienced in?

Lukasz is most experienced in business areas like Information Technology (IT), Product Development, and Operations.

Which industries has Lukasz worked in recently?

Lukasz has recently worked in industries like Information Technology (IT) and Banking and Finance.

Which business areas has Lukasz worked in recently?

Lukasz has recently worked in business areas like Information Technology (IT), Operations, and Product Development.

What is Lukasz's education?

Lukasz holds a Bachelor in Computer Science from Saigon International University.

What is the availability of Lukasz?

Lukasz is immediately available full-time for suitable projects.

What is the rate of Lukasz?

Lukasz's rate depends on the specific project requirements. Please use the Meet button on the profile to schedule a meeting and discuss the details.