Hi, I'm José Alejandro Berrío
Lead Software Engineer | Backend Specialist | Fintech Expert
9+ years building scalable fintech platforms across LATAM. I lead teams, architect distributed systems, and deliver measurable impact — from launching payment solutions processing 1M+ monthly transactions to building loyalty platforms serving 700+ businesses.
About Me
I'm a Lead Software Engineer with 9+ years of experience building fintech and B2B platforms across Latin America. I've led teams of up to 9 engineers at companies like Mercado Libre, Rappi, and Leal — delivering systems that process millions of transactions and serve hundreds of thousands of users.
I'm passionate about backend engineering, distributed systems, and mentoring teams to deliver high-impact products. I thrive in fast-paced environments where technology directly drives business outcomes.
Languages I speak:
Spanish
Native
English
Fluent (C2)
Portuguese
Intermediate
Career Highlights
Key projects that showcase my leadership and technical impact
Mercado Pago — QR Payments
Spearheaded a cross-functional team of 9 engineers to architect and deploy a QR-based payment solution for Buenos Aires, achieving rapid market adoption and scaling to process over 1M transactions monthly within months of launch.
Impact & Leadership
- •Coordinated iOS, Android, and Backend teams through complete product development cycle
- •Designed robust payment infrastructure capable of handling 1M+ monthly transactions
- •Achieved and maintained 100% SLA compliance for over 12 consecutive months
- •Developed secure encryption and QR signing mechanisms for transaction integrity
Leal — Loyalty Platform
Orchestrated a 7-member engineering team to architect and expand a comprehensive loyalty and rewards ecosystem serving over 1M users and 700+ partner businesses throughout 8 Latin American markets.
Impact & Leadership
- •Designed backend systems using Go and Node.js while overseeing Flutter-based frontend
- •Expanded platform reach to 700+ businesses across 8 countries in Latin America
- •Enhanced transaction reconciliation performance by 30% for co-branded credit card integration
- •Coached engineers and implemented best practices for distributed system architecture
RappiPay — Financial Products
Pioneered RappiPay's financial services platform, delivering Colombia's first co-branded credit card partnership with Davivienda and a digital savings account that attracted over 100K users across Latin America.
Impact & Leadership
- •Designed and implemented backend systems for money transfers, credit cards, and savings accounts
- •Established strategic co-branded credit card partnership with leading Colombian financial institution
- •Grew savings account user base to 100K+ active customers throughout LATAM
- •Established technical foundation enabling Rappi's strategic expansion into financial technology
Work Experience
Project Leader
Mercado Libre - Mercado Pago
2024 – Present
Buenos Aires/São Paulo/Medellín
- •Directed a 9-engineer team (5 iOS, 4 Android) delivering key payment features for millions of users
- •Launched QR payment solution in 2 months, scaling to 300K+ transactions in the first month and over 1M monthly later
- •Eliminated multi-year technical debt and sustained SLA "Above" rating with 100% compliance for 12+ months
- •Implemented encryption and QR signing algorithms; led hiring, mentoring, PR reviews, and career plans
Technical Leader
Leal
2022 – 2024
Bogotá
- •Led 7 engineers designing a loyalty platform with 1M+ users and 700+ businesses across 8 countries
- •Architected backend (Go, Node.js) and coordinated Flutter frontend to accelerate product delivery
- •Maintained and enhanced co-branded credit card system with Davivienda, improving transaction reconciliation speed by 30%
Senior Principal Software Engineer
Prodigious (Publicis Global Delivery)
2021 – 2022
Paris, France
- •Developed backend services in Node.js, Java, React, and Azure, supporting international clients
- •Spearheaded internal frameworks (Knex, Spring Boot) and conducted 20+ interviews for senior Node.js engineers
Software Development Engineer
Baires Dev
2021
San Francisco, USA
- •Built Node.js backend for Instructure LMS used by thousands of educators
- •Delivered backend & DevOps for Waitr App, optimizing CI/CD pipelines and cloud deployments
Software Engineer
Rapicredit
2020 – 2021
Bogotá
- •Developed APIs with Java Spring Boot and Drools rule engine for automated credit risk scoring
- •Implemented Angular components, reducing frontend defect rate by 15%
Intermediate Backend Developer
Rappi
2018 – 2020
Bogotá
- •Co-created RappiPay: enabled money transfers, launched first co-branded credit card with Davivienda, and savings account adopted by 100K+ users
Development Consultant
SETI / SURA
2016 – 2020
Medellín
- •Engineered proposal management platform (Angular, Java EE, Oracle) improving sales efficiency by 25%
- •Delivered insurance quoting/sales system (GuideWire, Angular, Scala) handling thousands of monthly policies
Skills & Technologies
Core competencies and tools I work with daily
Backend & APIs
Node.js
Server-side JavaScript runtime for scalable applications
TypeScript/JavaScript
Type-safe JavaScript for robust codebases
PHP
Web applications and APIs
Java
Enterprise applications and microservices
Go
Enthusiast in high-performance concurrent systems
Python
Enthusiast in data processing and scripting
Cloud & DevOps
AWS
Cloud infrastructure and services
Kubernetes
Container orchestration platform
Docker
Application containerization
Terraform
Infrastructure as code
Kafka
Distributed event streaming
Databases & Storage
PostgreSQL
Relational database for complex queries
MySQL
Popular open-source relational database
DynamoDB
NoSQL database for high-scale applications
Redis
In-memory data store for caching
MariaDB
MySQL-compatible relational database
Frontend & Mobile
React
UI library for web applications
Angular
Full-featured web framework
Vue
Progressive JavaScript framework
Next.js
React framework for production
Tools & Practices
Git
Version control and collaboration
Jira
Project management and tracking
Datadog
Monitoring and observability
Jest
JavaScript testing framework
Projects & Open-Source
Featured repositories showcasing my technical breadth and problem-solving approach
Inventario Suite
Full-stack inventory + store demo with modular architecture and multiple frontend frameworks
- •Angular storefront (Tienda), React/Next.js admin (Inventario)
- •NestJS and Koa backend services with Docker orchestration
- •Demonstrates end-to-end delivery and framework flexibility
Nest Events
Event management app with NestJS backend and Vue/Tailwind frontend
- •Clean scripts for dev/prod/test environments
- •Lightweight component-driven UI with Tailwind CSS
- •Full API + UI integration example
Coordinadora API Tracking
Lightweight integration to query and normalize Coordinadora shipment tracking
- •Normalizes carrier responses into consistent domain model
- •Useful for e-commerce backends and logistics dashboards
- •Clean TypeScript SDK with comprehensive tests
Fuleo
Angular scaffold with unit/e2e testing demonstrating front-end test discipline
- •CLI scaffolding with testing commands
- •Clear folder structure for scalable applications
- •Karma and Protractor test setup
Memoization in Node.js
Tiny, readable memoization utility using closures for performance optimization
- •Simple code with strong clarity
- •Demonstrates attention to performance basics
- •Practical utility for caching expensive computations
LeetCode Practice
Hundreds of data structures and algorithms solutions demonstrating consistency and breadth
- •Coverage: arrays, trees, DP, graphs, scheduling, and more
- •Strong signal for problem-solving and pattern recognition
- •Years of consistent practice and learning
Personal Site
Monorepo for my public portfolio site (alejo86a.com)
- •Fast static delivery with GitHub Pages
- •Professional branding and contact links
- •Responsive design with modern stack
Production case studies (Mercado Pago QR, RappiPay, Leal) available on request; code is private.
Professional Case Studies
Private codebases with measurable business impact
Mercado Pago — QR Payments
Led 9-engineer team; launched in 2 months; scaled from ~300K to 1M+ monthly transactions; 100% SLA year-long.
RappiPay — Cards & Savings
Co-branded credit card and savings account with Davivienda; backend processes in regulated fintech context.
Leal — Loyalty Platform
Led 7-person team; 1M+ users / 700+ businesses in 8 countries; improvements to transaction reconciliation.
Education & Achievements
Education
Systems Engineering
Metropolitan Institute of Technology (ITM)
Medellín, Colombia
2024
Diploma in Cloud Computing Fundamentals
Metropolitan Institute of Technology (ITM)
Medellín, Colombia
2024
Diploma: Leadership in an Age of Disruption
California State University, Northridge
Los Angeles, California
2022
Diploma in Advanced Architecture with Microservices
University of Antioquia (UdeA)
Medellín, Colombia
2018
Systems Engineering
University of Antioquia
Medellín, Colombia
2012 – 2016
Systems Technique
SENA
Medellín, Colombia
2011
Career Achievements
Mercado Pago: QR payments scaling from 0 to 1M+ monthly transactions
RappiPay: Launched first co-branded credit card and savings account adopted by 100K+ users
Leal: Loyalty platform with 1M+ users and 700+ businesses in 8 countries
Hackathons: Startup Weekend Medellín (IoT, Fintech Challenge), Apps.co finalist
Founder: Peiname.co MVP (Android/iOS), marketing & customer discovery
Let's Connect
Interested in collaborating, hiring, or discussing a potential opportunity? I'd love to connect — let's talk!
Location
Medellín, Colombia
GitHub
github.com/alejo86a© 2025 José Alejandro Berrío Marín. Built with Next.js and deployed on GitHub Pages.
My Development Setup
Want to build a setup like mine? Here are the tools and gear I use daily for coding, streaming, and productivity. All products are tested and recommended based on my real-world experience.
EPOMAKER RT100
Retro mechanical keyboard with 97 keys, three-mode connectivity (BT5.0/2.4G/USB-C), hot-swappable switches, RGB backlight, and smart display with knob.
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EMEET PIXY 4K
AI-powered 4K PTZ dual-camera with AI tracking, PDAF auto-focus, Sony sensor, 3 built-in microphones, and gesture control — ideal for video calls and streaming.
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DeltaHub Carpio 2.0
Ergonomic wrist rest for mouse — provides carpal tunnel support, pain relief, anti-fatigue comfort, and easy-glide design for long coding sessions.
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ARZOPA 17.3" Portable Monitor
17.3" 1080P FHD portable monitor with 103% sRGB IPS panel, built-in stand, HDMI and USB-C — extends your workspace anywhere.
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UGREEN 5-Port Gigabit Switch
Compact 5-port Gigabit Ethernet switch — plug-and-play, unmanaged, with LED indicators for reliable wired connections at home or office.
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NerdEthos 4K HDMI Switch
4K@60Hz HDMI switch with 4 inputs and 1 output, remote control, HDR10, and HDCP 2.2 — easily switch between PC, PS4, Xbox, and streaming devices.
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Luonanava 8-in-1 USB-C Hub
8-in-1 USB-C hub with 4K HDMI, Gigabit Ethernet RJ45, 100W PD charging, USB 3.0 ports, SD/TF card reader — perfect for MacBook, Dell, and HP laptops.
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JSAUX 8K HDMI 2.1 Cable
Ultra high-speed 8K HDMI 2.1 cable (10ft, 2-pack) supporting 48Gbps, 8K@60Hz, 4K@120Hz, eARC, HDR10, and HDCP 2.2/2.3 for flawless display connections.
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M-Audio BX4 Studio Monitors
4.5" 120W studio monitor speakers (pair) delivering professional-grade, reference-flat audio for music production, mixing, and everyday listening.
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UGREEN Bluetooth 5.1 Receiver
Hi-Res audio Bluetooth 5.1 receiver with LDAC support, low latency, RCA and 3.5mm aux outputs — upgrades any wired home stereo or speakers to wireless.
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Fromann L-Shaped Standing Desk
L-shaped electric standing desk frame with triple motor, 3-leg design, height and width adjustable sit-stand base — transforms any desk into an ergonomic workstation.
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BYMECOST Under-Desk Laptop Mount
Metal under-desk laptop mount that stores your MacBook or laptop out of sight, freeing desk space — fits devices up to 1.37" thick.
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VIKTOR JURGEN Shiatsu Massager
Deep-tissue kneading 3D Shiatsu massage pillow with heat — relieves back, neck, shoulder, and leg pain after long coding sessions. A must for any home office.
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