Available for remote work
Gian Barboza

Gian Barboza

Senior Backend Engineer

Senior Backend Engineer with 10+ years building distributed systems, payments infrastructure (Stripe, PayPal, DLocal, Shift4), and AI-powered automation. Ex-CTO who ships production-first solutions.

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📈

Key Impact

⏱
10+

Years of Experience

📈
99.9%

Uptime on Critical Infrastructure

💰
$200K+

Transactions Processed / Month

💳
5+

Payment Providers Integrated

🧭

Journey

From junior developer to CTO and senior backend on payments platforms

  1. Nov 2023 — Present

    Senior Backend Engineer

    Hablax Inc. · 100% Remote

    Leading AI-driven initiatives on the giftcards and top-up platform: AI-generated programmatic SEO, fraud detection engine with extensible rules, gateways to modernize legacy services, and a multi-channel notification orchestrator.

  2. Apr 2023 — Nov 2023

    Full Stack Engineer · Freelance

    Independent clients · Remote

    Built an end-to-end digital-goods e-commerce with a modern stack: Next.js, TypeScript, Clean Architecture, Vitest, and GitHub Actions CI/CD. Full Stripe and PayPal integration, delivery automation, and custom admin system.

  3. Dec 2017 — Apr 2023

    Full Stack Developer → CTO

    Hablax Inc. · 100% Remote

    Grew from developer into CTO leading a team of 4 developers. Designed the migration from monolith to an 8-server distributed infrastructure on DigitalOcean, integrated the core payment processors (PayPal, Payeezy, DLocal), and built the multi-provider product engine with automatic failover.

  4. Jan 2016 — Mar 2017

    Java Software Developer

    Fermat.org · 100% Remote

    Built P2P Android apps on top of cryptocurrencies (taxi, e-commerce) where payments landed directly in the provider's wallet with no intermediaries. First exposure to decentralized systems and 100% remote work.

🛠️

Technical Expertise

⚙️ Backend & Architecture

Node.js TypeScript Next.js PHP Java REST API Gateway Pattern Design Patterns Clean Architecture

🏗️ Infrastructure

Linux HAProxy Nginx MySQL Replication DigitalOcean Cronjobs CI/CD

💳 Payments & Risk

Stripe PayPal DLocal Shift4 Payeezy Payment Routing Fraud Rule Engines Device Fingerprinting PCI Compliance

🤖 Automation & AI

n8n LLM Integration AI-Assisted Fraud Programmatic SEO Content Automation Web Scraping
💼

Case Studies

Real problems, technical decisions, and measurable outcomes

⚡

Monolith to Distributed Infrastructure Migration

📍 Context

Giftcards and top-up platform processing ~1,000 transactions/day and $100K–$300K in monthly volume, running on a single server.

⚠️ Problem

Recurring ~3-hour outages during traffic spikes (Mother's Day, New Year's Eve) because the calling system consumed all resources. Direct revenue loss on the most lucrative days of the year.

🧩 Technical Decision

Migrated to DigitalOcean with 8 servers separating concerns (web, database, dev). HTTP load balancing with HAProxy, MySQL master-slave replication for high availability, node-level failover, automated backups and recovery runbooks. Executed manually over Linux due to legacy-stack constraints, leading a team of 4 developers.

HAProxy MySQL Replication Linux DigitalOcean Nginx Apache
99.9% uptime sustained since 2019 · Zero outages during peak dates over the last ~5 years
🚀

Programmatic SEO with AI at Scale

📍 Context

Thousands of dollars in monthly paid-ad spend, with a catalog of 1,600+ products per provider multiplied across multiple countries and services.

⚠️ Problem

Reduce paid-ad dependency without hurting acquisition. Generating content at human scale for thousands of country/service/product combinations was unfeasible.

🧩 Technical Decision

Hierarchical generation pipeline across 3 tiers (country → country/service → country/service/product), populating thousands of combinations via ChatGPT-4o with prompts curated per vertical. Automatic trigger: when a new product lands, affected landings are regenerated with zero manual intervention.

ChatGPT-4o Node.js AI Content Gen Programmatic SEO PHP
Significant replacement of ad spend with organic traffic · Better new-client ratio than the paid channel · Scales autonomously with the catalog
🛡️

Fraud Detection with Extensible Rule Engine

📍 Context

Payments platform exposed to two fraud vectors: transactional (stolen cards, suspicious patterns) and access-level (multi-accounts, account-takeover attempts).

⚠️ Problem

Need to add new rules frequently without touching the central pipeline, and to detect suspicious account/device patterns without degrading the experience for legitimate users.

🧩 Technical Decision

Rule engine based on Factory + Single Responsibility: each rule self-registers and receives normalized context, allowing extension without modifying the evaluator. Separate access-fraud layer using device fingerprinting. Explored contextual LLM evaluation via n8n to mimic support agents' decisions; it worked at small scale but was shelved due to prohibitive model costs.

Design Patterns Factory SRP Device Fingerprinting n8n LLM
Significant reduction in manual review load · Technical foundation to ship new rules in hours instead of weeks
💳

Multi-Gateway Payments Integration with Failover

📍 Context

Global giftcards and top-up operation where relying on a single gateway leaves gaps in geography, conversion, and availability.

⚠️ Problem

Different gateways cover different countries and fees; any one of them can go down or start rejecting more. We needed continuous coverage and commercial flexibility to optimize per country and method.

🧩 Technical Decision

Abstraction where the admin configures the active gateway and priorities per product. On failure or rejection from the active provider, automatic failover to the next in the chain. 5 processors integrated (PayPal, Payeezy, DLocal, Stripe, Shift4) with full features: 3DS, refunds, voids, Apple Pay, Google Pay, and in-house card tokenization.

Stripe PayPal DLocal Shift4 Payeezy 3DS Apple Pay Google Pay Tokenization
Continuous payment availability during provider incidents · Routing optimized for cost and conversion · 5 gateways in production
🎯

Leadership & Focus

Leadership Experience

  1. Former CTO with end-to-end product ownership

  2. Led a team of 4 developers through critical infrastructure migrations

  3. Production-first engineering culture focused on high availability

  4. Technical strategy, system design, and architecture decisions

What I'm Looking For

  • Senior Backend / Platform Engineering roles
  • Remote-first opportunities
  • Challenges in distributed systems, payments, or critical infrastructure
  • Teams that value ownership & craft
✉️

Let's Work Together

Available for full-time remote opportunities

Download Resume +57 304 358 1365 LinkedIn GitHub