Open to opportunities

Lucas Krämer de Sousa

@lucaskrmerdesousa

Message

Senior Backend Engineer and API architect delivering scalable cloud-native SaaS solutions.

Brazil

Message

What I'm looking for

I seek backend or full-stack roles where I can architect cloud-native systems, solve high-scale integration challenges, mentor teams, and expand into new industries and React development.

I am a Senior Backend Engineer and API architect with over a decade building SaaS platforms, cloud-native services, and scalable integrations.

I specialize in Python (Django, FastAPI, Pydantic), Node.js/TypeScript (Express, GraphQL), and databases such as PostgreSQL, MongoDB, Redis, and DynamoDB. I design solutions that handle high-rate webhooks and complex user management (ABAC).

I architect and implement AWS-based systems (Lambda, SQS, SNS, RDS, API Gateway, ECS), lead migrations, and deliver measurable business outcomes as a consultant across industries.

I mentor aspiring developers, collaborate with cross-functional teams, and am open to Full Stack opportunities to grow my React skills while applying my backend expertise to new domains.

Experience

Work history, roles, and key accomplishments

Current

Senior Back-End Developer

Current

Loka

Oct 2023 - Present (1 year 11 months)

Design and deliver custom backend solutions using FastAPI and Pydantic, and architect cloud-native systems on AWS (SQS, SNS, Lambda, API Gateway) to ensure scalability for diverse clients.

Python fastAPI Pydantic AWS Lambda SQS SNS API Gateway Cloud Architecture

Youth Mentor

Prototipando a Quebrada

Sep 2024 - May 2025 (8 months)

Guided young people in programming fundamentals and real-world software development practices, fostering problem-solving and hands-on project experience.

Mentoring Teaching Curriculum Development Python Project Based Learning Youth Engagement

Senior Software Engineer

Engefoto - Engenharia e Aerolevantamentos S.A.

Jun 2023 - Oct 2023 (4 months)

Developed geospatial data sampling and analysis software using Ruby on Rails and PostGIS, implementing complex spatial queries and data processing workflows in PostgreSQL.

Ruby on Rails PostGIS PostgreSQL Geospatial Data Processing Spatial Analysis

Backend Engineer

REISift - Real Estate Sales and Marketing Ninjas

Apr 2021 - Jan 2023 (1 year 9 months)

Built and scaled a Real Estate Investing CRM using Django REST Framework and AWS serverless components, integrating payments (Stripe), HubSpot, and high-rate webhooks (~30 rps with Aircall).

Django REST Framework Python AWS Serverless Stripe HubSpot Webhooks Scalability PostgreSQL

Backend Engineer

Octadesk.com

Oct 2019 - Apr 2021 (1 year 6 months)

Designed Node.js microservices for an omnichannel digital marketing platform, improved back-office integrations with HubSpot and payments, and migrated accounts/users from MongoDB to PostgreSQL.

Node Express Microservices MongoDB PostgreSQL HubSpot Payments Data Migration

Backend Developer

SmartMEI

Jan 2019 - Oct 2019 (9 months)

Built payment and billing infrastructure for a financial mobile app serving 10,000+ customers using Node.js/TypeScript, GraphQL, and Firebase architecture.

Node TypeScript GraphQL Firebase Payments Billing Scalability

Software Engineer

Resultados Digitais

May 2016 - Jan 2019 (2 years 8 months)

Developed core features for a marketing SaaS used by 5,000+ businesses and improved performance using MongoDB, Redis, and PostgreSQL within AWS/Heroku environments.

MongoDB Redis PostgreSQL AWS Heroku Performance Optimization SaaS Development

Full Stack Developer Intern

Resultados Digitais

Jan 2015 - May 2016 (1 year 4 months)

Built and tested features for a Ruby on Rails marketing platform, progressed from intern to software engineer, and led technical support efforts to convert manual tasks into scalable features.

Ruby on Rails Testing Agile Technical Support

Application Tester

INCoD - Instituto Nacional para Convergência Digital

Jul 2012 - Jan 2015 (2 years 6 months)

Conducted black-box testing for a healthcare platform tracking toxicological cases, identifying and documenting defects to ensure medical data integrity and system reliability.

Black Box Testing QA Test Case Documentation Healthcare Software Test Reporting

Education

Degrees, certifications, and relevant coursework

UniCesumar

Bachelor's Degree, Software Engineering

2020 - 2023

Bachelor's degree in Software Engineering completed at UniCesumar with coursework and projects focused on software development and engineering practices.