Public health · 2020

A contact-tracing app,
donated, not invoiced.

A privacy-preserving, Bluetooth-based contact-tracing platform for Panama's COVID-19 response — architected, shipped, open-sourced, and donated. Modelled on Singapore, Germany and the UK; engineered to run on older phones without draining the battery.

Client
Public health initiative · Panama
Year
2020
Role
Architecture, mobile (iOS/Android), cloud
Model
Donated · Open source · Pro-bono
  • 2020
    built during Panama's first pandemic wave
  • 15m
    effective BLE proximity range
  • 0
    GPS, personal data, or central identifiers
  • $0
    invoiced — full source handed over
The problem

A pandemic does not wait for procurement.

In March 2020 Panama needed digital contact tracing in days, not quarters. Standard government IT timelines — RFPs, vendor evaluation, staged pilots — were going to miss the curve entirely. Manual tracing didn't scale; GPS-based apps raised privacy and sovereignty concerns.

The constraint set was brutal: work on older low-cost phones, minimise battery drain, collect no personally identifiable data, and leave behind code the state could audit and maintain without us.

The approach

Privacy by design. Bluetooth, not GPS.

We studied the Singapore, German and UK models and landed on a decentralised, BLE-based architecture with rolling encrypted identifiers. Devices matched exposures locally; no location data ever left the phone. Positive cases uploaded anonymous broadcast IDs only after entering a health-authority verification code.

  • Mobile — React Native for iOS and Android with a custom BLE stack; local SQLite store, AES-256 encryption at rest, rolling identifiers rotating every 15–20 minutes.
  • Back-end — Ruby on Rails and Node.js on Postgres, Docker-packaged, JWT-authenticated, designed for millions of concurrent devices on modest infrastructure.
  • Privacy architecture — no PII, no GPS, no central identity graph; signal-attenuation modelling to reduce false positives across device manufacturers.
  • Handoff — full source open-sourced, runbooks and infra-as-code donated. No lock-in, no recurring fees, no ongoing dependency on us.
  • React Native
  • BLE
  • Ruby on Rails
  • Node.js
  • Postgres
  • Docker
  • SQLite
  • AES-256
Outcome

Handed it over. Walked away.

The platform was validated in controlled testing and covered in national media (La Prensa, TVN, Vida Digital). It was one of the earliest privacy-preserving contact-tracing implementations in Latin America, and contributed to the regional playbook for decentralised exposure notification.

The importance of using the simplest effective technology was the real lesson.— Team retrospective, 2021

For us, Cerco settled a principle that still shapes our client selection today: when the work matters enough, the senior team shows up for free — and leaves no invoice, no lock-in, and nothing you can't run yourself.

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