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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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 gift cards 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.

Key Impact

10+

Years of Experience

99.9%

Uptime on Critical Infrastructure

$200K+

Transactions Processed / Month

5+

Payment Providers Integrated

Case Studies

Real problems, technical decisions, and measurable outcomes

Monolith to Distributed Infrastructure Migration

Context

Gift cards 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 gift cards 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

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

Let's Work Together

Available for full-time remote opportunities

Download Resume +57 304 358 1365 LinkedIn GitHub