joseasantacruz

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Senior Full Stack Engineer | Ruby on Rails, React, TypeScript | SaaS Billing & Subscriptions (Stripe, Chargebee) | Remote
June 13, 1989

About Candidate

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Senior Ruby on Rails / Full Stack Engineer with 10+ years of experience building and scaling revenue-critical SaaS platforms for US-based companies.
Specialized in billing, subscriptions, invoicing, and payment workflows, working extensively with Stripe, Chargebee, and Salesforce, where correctness, performance, and reliability directly impact revenue and customer trust.

Backend-heavy engineer with strong full-stack ownership, delivering end-to-end features including data modeling, API/GraphQL design, background jobs, performance optimization, frontend development with React and TypeScript, automated testing, and production releases. Experienced working in high-traffic, multi-tenant SaaS systems and collaborating remotely with distributed, English-speaking teams.

Core strengths: Ruby on Rails, PostgreSQL, SaaS architecture & system design, billing & subscription systems, Stripe, Chargebee, Salesforce, performance optimization, background jobs, RSpec, Cypress, AWS.

Education

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Computer Engineering 2016
Universidad Nacional de Asunción

Work & Experience

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Senior Full Stack Engineer (Ruby on Rails, React, TypeScript) – US SaaS Client May 2022 - December 2025
BairesDev — US SaaS Client

Senior Full Stack Engineer on a high-traffic SaaS platform built with Ruby on Rails, PostgreSQL, React, and GraphQL.
Owned and scaled billing and subscription systems for a high-traffic, multi-tenant SaaS platform, supporting revenue-critical workflows.
Implemented and maintained Stripe and Chargebee billing, including subscription lifecycle, invoicing, payment reconciliation, and billing edge cases.
Designed backend services and data models in Ruby on Rails and PostgreSQL to ensure financial accuracy and data consistency.
Built and maintained GraphQL APIs consumed by React and TypeScript frontends for complex SaaS workflows.
Improved backend performance through query optimization, caching strategies, and background job processing, reducing latency and improving throughput.
Ensured production reliability with automated testing (RSpec, Cypress) and safe deployment practices.
Collaborated remotely with US-based product and engineering teams in a distributed environment.

Technical Skills: Ruby on Rails, PostgreSQL, React, TypeScript, GraphQL, Stripe, Chargebee, Salesforce, SaaS Architecture, Billing & Subscription Systems, Background Jobs, Performance Optimization, RSpec, Cypress, AWS.

S
Senior Backend / Full Stack Engineer (Ruby on Rails) – Fintech SaaS July 2020 - December 2022
GLASIR LABS S.A. — Fintech SaaS

Senior Backend / Full Stack Engineer on a crowdlending fintech SaaS platform built with Ruby on Rails, PostgreSQL, and AWS.
Designed and maintained backend services for a fintech SaaS platform handling high-volume financial transactions, ensuring scalability and reliability.
Built and optimized APIs and background processing systems in Ruby on Rails and PostgreSQL, ensuring data consistency and fault tolerance.
Integrated third-party payment and financial services supporting core lending and investment workflows.
Improved system performance and operational stability through database tuning, infrastructure optimization, and monitoring.
Collaborated closely with product and business stakeholders in a regulated fintech environment, delivering high-impact features.

Technical Skills: Ruby on Rails, PostgreSQL, AWS, Background Jobs, API Design & Optimization, Payment Gateway Integration, SaaS Architecture, Performance Optimization, Monitoring.

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Backend Engineer (Python / Django) July 2021 - April 2022
Flat.mx — Automation & Integrations

Backend Engineer focused on automation and integrations using Python, Django, PostgreSQL, Docker, and AWS.
Developed backend services and APIs supporting business-critical internal and customer-facing workflows.
Implemented integrations with HubSpot, Zapier, Trengo, and Customer.io to automate marketing and operations processes.
Improved system performance, reliability, and observability across internal services.
Worked closely with product, marketing, and operations teams in a remote-first environment, delivering reliable end-to-end solutions.
Technical Skills: Python, Django, PostgreSQL, Docker, AWS, API Development, Automation & Integrations, System Observability, Third-Party Integrations.

S
Software Engineer / Data & BI Engineer April 2011 - November 2019
TU Financiera S.A.E.C.A. — Banking Systems

Software Engineer working on banking systems and data platforms supporting home banking applications and financial reporting.
Designed and maintained data models, ETL pipelines, and data warehouse solutions using PostgreSQL, Oracle, and MySQL.
Built backend services and APIs using PL/SQL, PL/Python, SOAP, and REST.
Developed BI dashboards and regulatory reports using Oracle BI and Tableau.
Led a small development team for approximately two years, responsible for BI dashboards and reporting solutions.
Supported large-scale financial systems with strict requirements for accuracy, performance, and reliability.
Technical Skills: PostgreSQL, Oracle, MySQL, PL/SQL, PL/Python, SOAP, REST APIs, ETL, Data Warehousing, Oracle BI, Tableau, Team Leadership, Financial Systems.