Case study
Logistics & E-commerce
A Shopify app that brings Flash Courier's shipping and tracking into every store
Flash Courier, a Brazilian courier, wanted stores on Shopify to offer its delivery at checkout without manual work. We designed, built and run a free Shopify app that quotes the real price and delivery time for each order and sends the tracking code to the customer automatically.
- Client
- Flash Courier
- Platform
- Shopify App Store
- Industry
- Logistics & E-commerce
- Launched
- 2024
The challenge
Stores that shipped with Flash Courier had no direct integration with Shopify. They charged flat or table-based shipping, customers only saw the delivery time after paying, and staff copied tracking codes into each order by hand.
What we built
A native Shopify app, written in Rust, that connects each store to Flash Courier's official shipping calculators. Free on the Shopify App Store; stores need a Shopify plan with carrier-calculated shipping and a contract with Flash Courier.
Live shipping at checkout
When the customer enters the address, Shopify asks the app for rates. The app quotes Flash Courier with the destination postcode and the total weight and returns each delivery option with its price and delivery time. It works with API keys for São Paulo and Rio de Janeiro.
Automatic tracking
When an order shipped with Flash Courier is fulfilled, the app saves the tracking code and link to it, and Shopify emails the customer. The code prefix is configurable, with a live preview.
Self-explanatory admin
Built with Shopify's own Polaris components: a 3-step checklist, help on every field, a FAQ, Shopify's save bar and a clear warning when the store's plan lacks carrier-calculated shipping.
A checkout that never breaks
Every step has a time limit. If Flash Courier is slow or down, Shopify shows the store's backup rates, so the customer never runs out of delivery options because of the app.
Ready for Shopify's new rules
The app already uses the expiring access tokens that Shopify will require from public apps in January 2027, renewed automatically, and it verifies the signature of every message from Shopify.
A website with a 3D mode
A public site presents the app, with an "Explore in 3D" island where a Flash Courier truck follows an order from the store to the customer. It scores 100 on Lighthouse and loads in 0.9 s.
Engineering results
Measured in production in September 2026. Quote time is the typical end-to-end time, not a contractual guarantee.
- Kubernetes with two app instances, and PostgreSQL with a primary and two read replicas
- Real-time error monitoring with Honeybadger on quotes, tracking and token renewal
- LGPD-compliant: no data about the stores' customers is stored
- Tracking is retried until Shopify confirms it, so no order loses its code
Technology
- Rust
- Shopify Carrier Service
- Shopify Webhooks
- Polaris
- PostgreSQL
- Kubernetes
- Honeybadger
- three.js
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