Open to opportunities

Rafael Hashimoto

@rafaelhashimoto

Message

Senior full-stack engineer (Ruby on Rails) delivering reliable B2B SaaS features that boost growth.

Brazil

Message

What I'm looking for

I’m looking for a dedicated team where I can apply senior-level technical expertise and innovation to solve hard problems—improving reliability, performance, and developer experience while driving complex cross-functional initiatives.

I’m a Senior Software Engineer with 10+ years of experience building and scaling B2B SaaS products. I focus on delivering high-impact software with strong attention to reliability, performance, and developer experience, using the tools and practices that make systems easier to ship and safer to run.

In my recent work, I’ve driven measurable outcomes like a 12% checkout conversion lift through a React/TypeScript + Ruby on Rails redesign, and I’ve reduced incident response time by 90% by defining SLIs and SLOs with Nobl9 and aligning service-level metrics to business SLAs. Earlier I cut HABITE-SE document generation time by ~99% (from 7 days to ~30 minutes) using REST APIs and streamlined inter-department data exchange, and built a caching layer in front of an 8M-report/month PDF rendering service that avoided ~1.6M duplicate renders per month (~20% cache hit rate). I’m comfortable owning core systems end-to-end — feature flags and safer rollouts (Flagsmith), resilient releases (GitHub Actions + AWS ECS), and scalable monolith-to-microservice extraction — while mentoring engineers and collaborating across functions.

Experience

Work history, roles, and key accomplishments

Current

Senior Software Engineer

Current

Remotely.works

Sep 2024 - Present (1 year 10 months)

Owned and evolved core systems for a B2B pet compliance and risk assessment SaaS using Ruby on Rails and React/TypeScript. Delivered a full-stack checkout redesign and implemented safer feature flag rollouts and release management via GitHub Actions and AWS ECS.

Ruby on Rails React TypeScript REST APIs PostgreSQL Redis Flagsmith Feature Flagged Releases GitHub Actions AWS ECS

Senior Software Engineer

FullStack Labs

May 2021 - Sep 2024 (3 years 4 months)

Worked on a B2B enterprise construction management SaaS, focusing on scaling PDF report processing and migrating template/rendering functionality into microservices. Maintained front-end components and supported a production reliability approach during service extraction.

Ruby on Rails REST APIs PostgreSQL Redis Sidekiq AWS EC2 AWS S3 AWS Cloudwatch AWS RDS React TypeScript Redux ArgoCD Microservices Caching Eventual Consistency

Full Stack Engineer

Jobsity

Jun 2020 - May 2021 (11 months)

Built full-stack solutions for a Germany-based mobility SaaS offering a standardized API platform for public transport data and ticketing integrations. Implemented a railway traffic visualization platform and a GTFS import pipeline for ingesting and updating datasets.

Ruby on Rails React Docker Docker Compose PostgreSQL PostGIS GTF API Integration

Full Stack Engineer

Secretaria Municipal de Finanças

Jul 2018 - Jun 2020 (1 year 11 months)

Developed and improved systems for the city of Fortaleza’s tax administration and financial systems. Increased test coverage with RSpec/TDD, built REST APIs and a Python Flask tax prediction API, and created a geospatial React-based visualization tool.

TDD RSpec Ruby on Rails REST APIs Sidekiq Redis Flask API Docker Docker Compose React Redux Geoserver OpenLayers

Ruby on Rails developer

Intersol

Jan 2018 - Jun 2018 (5 months)

Contributed to a system for managing town hall taxes and bidding processes, including developing API integrations and administering a PostgreSQL database.

Ruby on Rails API Integration PostgreSQL