Most people using BarterGrid will never think about any of this, and that's the point — the technology should stay invisible. But if you're the kind of person who wants to know what's actually running under the hood, here's the honest rundown.
The app itself
Built in Flutter, so the same codebase runs on iPhone, Android, and the web instead of maintaining three separate apps. It's what lets a small team ship changes to everyone at once.
The backend
Runs on Kubernetes on Google Cloud — a setup that scales up automatically when there's more traffic and scales back down when there isn't, so we're not paying for capacity we don't need. Behind that are a handful of focused services: one for user profiles, one for matching, one for handling trades, one for notifications, and one for processing photos.
The matching engine
This is the part covered in more detail in how we match you with a trading partner — short version, it runs on Google's Vertex AI, trained on real trade outcomes so it gets better at predicting good matches over time.
Photo tagging
When you upload a photo of something you're trading, Google's Cloud Vision looks at it, figures out what it is, pulls any text out of it, and suggests tags — so listing something takes seconds instead of minutes of manual categorizing.
The reputation ledger
Covered in full in how your reputation stays yours — the short version is that we use Hedera Hashgraph, a distributed ledger, to record trade outcomes in a way that can't be quietly altered later, not even by us. We chose it over alternatives like Ethereum mainly for speed and cost: transactions finalize in a few seconds for a fraction of a cent, which matters when you're recording potentially millions of trades.
Keeping things running and secure
Standard, unglamorous stuff: encrypted traffic and storage, automated testing on every code change, monitoring that pages someone if something breaks, and infrastructure defined as code so changes are reviewed the same way we review app code.
None of this is meant to impress — it's meant to stay out of your way. If you're trading a spare bike for guitar lessons, you shouldn't have to think about any of it.
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