Hola, I'm Juan.I build the software behind conversations that sell.

Senior Product Engineer at charles, where brands run AI shopping agents on WhatsApp. I build the parts that let them try, test, and trust those agents before a customer ever writes in.

12+ years full stack
Medellín to Frankfurt

TypeScript
React
Vue
Next.js
Node
NestJS
Postgres
LLMs
WebRTC

I speak

Hola.Hello.Hallo.

ES Native
EN Full professional
DE B1, telc certified

JuanFrankfurt, usually online

Every reply here was written by hand. No AI in this chat, ironically.

Now

Making AI agents safe to launch

Senior Product Engineer (Fullstack) at charles, since March 2026

charles helps consumer brands sell and support customers on WhatsApp. Brands design their agents in a visual flow builder. I work across that builder, its backend, and Cowork, the AI copilot that builds and tests flows with you. Everything below is live on the platform.

Flow PreviewChat with a draft flow right on the canvas. The real engine runs, but no message goes out and no customer data changes.

Automated flow testingOne model writes test conversations from the flow, another plays the customer, and every run is scored on outcome and quality.

Cowork toolsTools that let the copilot run tests, explain a failure in plain words, and set up knowledge from chat.

Website knowledgePaste a URL. The site is crawled and turned into answers the agent can use.

The path so far

My career, drawn the way I draw flows

12+ years, two countries, nine stops. Mostly real-time communication, health products, and lately AI that talks to people.

Start2011 to 2016

Universidad Nacional de Colombia

Software and Informatics Engineering

Medellín. Where it started.

Step2013 to 2014

CTZEN.co

Engineer

Built the core web app in Ember.js, while still studying.

Step2014 to 2016

Innventto

Web and mobile engineer

Projects for Volkswagen France and several published iOS apps.

Step2017

Globant

Frontend Engineer

Analytics for J&J Pharmaceuticals and Southwest Airlines ETOPS.

Step2018

Sangoma

Software Engineer, remote

Multiparty video conferencing for an enterprise communications platform.

Step2019 to 2021

MindDoc by Schön Klinik

Full-stack web and mobile

Therapist booking for thousands of users, a UI redesign, and my first hiring loops. Moved to Germany.

Step2021 to 2023

Chintai

Senior, then Lead Engineer

Led an exchange platform end to end and built its KYC flow. The platform was regulated by the Monetary Authority of Singapore.

Docker containers 4GB to 500MB

Step2024 to 2026

Hero Journey Club

Senior Software Engineer, 4th engineering hire

Owned the real-time audio platform for 11,000+ users across mental health and education, including native audio on mobile.

AI replies 4s to 1.5s

Live2026 to now

charles

Senior Product Engineer (Fullstack)

Preview, testing, and Cowork for WhatsApp AI agents.

4s1.5s

AI reply time on Shadowlight at Hero Journey Club, after rebuilding the conversation engine with swappable speech and language models.

~~4GB~~500MB

Docker container size at Chintai, after folding 7 to 8 apps into one pnpm and Turborepo monorepo.

11,000+

People on the real-time audio platform I owned at Hero Journey Club: backend, web, and mobile.

~~4th~~8

Joined Hero Journey Club as the 4th engineer and helped grow the team to 8.

Lead

Led an exchange platform at Chintai end to end, managing 2 engineers and running 2 workshops on development practices.