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Juan Sebastian Pérez Londoño

@juansebastianprezlon

Senior Ruby on Rails Engineer at Buk, taking payroll incidents from 30 a month to zero in a mature, multi-country codebase.

Colombia

Message

At Buk, I work on the payroll calculation engine used in five Latin American countries, where every rule change reaches real paychecks. I took recurring production incidents from 30 a month to zero by tracing root causes, improving observability and clarifying service boundaries, and redesigned core workflows as event-driven services on RabbitMQ.

I'm also building HeroClose, an AI sales agent for small businesses in Latin America on the WhatsApp Cloud API, with CRM, sales funnel and Google Calendar integration. Earlier, at Talenta 365, I built WhatsApp bot flows and candidate features; at DevPenguin, I built Rails products, including UPICK, and a native Android medical infusion calculator that won Shark Tank Colombia.

Experience

Work history, roles, and key accomplishments

Current

Senior Software Engineer, Backend

Current

Buk

Apr 2022 - Present (4 years 6 months)

Took recurring production incidents from 30 a month to 0 by tracing root causes, improving observability, and clarifying service boundaries. Delivered a multi-country engine change with Claude Code and redesigned core workflows as event-driven services on RabbitMQ, increasing throughput 4.9x.

Ruby on Rails RabbitMQ Event Driven Architecture Observability Root Cause Analysis CI CD Non Regression Tests Claude Code

Current

Founder and Lead Engineer

Current

HeroClose

Building an AI sales agent for small businesses in Latin America on the WhatsApp Cloud API, with CRM, sales funnel, and Google Calendar integration. App approved by Meta as a Tech Provider.

AI WhatsApp Cloud API CRM Google Calendar API SaaS

Technical Lead

Talenta 365

Jan 2020 - Mar 2022 (2 years 2 months)

Built WhatsApp bot flows, candidate registration, and video interview features in Ruby on Rails and React, covered by unit and integration tests. Led cross-functional teams and mentored mid-level and junior engineers.

Ruby on Rails React REST GraphQL SOAP Unit Testing Integration Testing Team Leadership Mentorship

Founder and Software Engineer

DevPenguin

May 2014 - Dec 2019 (5 years 7 months)

Built Ruby on Rails products end to end, from concept to production, leading small development teams. Built UPICK, a Rails platform for construction budgeting, and a native Android medical infusion calculator that won Shark Tank Colombia.

Ruby on Rails Android PayU Drive API Capistrano Team Leadership

Full Stack Developer

Coontigo

Oct 2015 - Jul 2016 (9 months)

Built a Moodle plugin and web service that fed an e-learning system's data into a Rails application for analysis and charts, working remotely on Spain's schedule.

Moodle Ruby on Rails Web Services Remote Work