Case study · 2025 · Blockchain · Web
Buying property abroad used to take six weeks of paperwork.Built a blockchain property platform. The whole purchase is one transaction, with proof of ownership stored on-chain forever.
Crypto Properties is a property marketplace on Ethereum: list, buy, sell, with an NFT ownership certificate moving to the new buyer atomically with payment. The studio shipped the smart contracts (Hardhat + Mocha test suite), the buyer / seller surfaces (Vite + TypeScript), and the indexer.
- Express
- Hardhat
- Mocha
- Vite
- TypeScript
Inside the build
Overview
- Atomic
- Payment + title transfer
- ERC-721
- Ownership certificate
- On-chain
- Provenance log
- Mocha
- Smart-contract tests
A platform to list, buy, and sell properties with Ethereum. Every sale comes with an NFT ownership certificate that proves who owns the property on-chain, and moves automatically to the new buyer.
What shipped
What it does
- Property catalogue with pricing
- Ethereum payments, integrated
- NFT ownership certificate per sale
- Ownership history on-chain
The problem
- Proving ownership is slow and paper-based
- Cross-border property buying is painful
- No transparent, tamper-proof registry
Why it matters
- Instant ownership transfer on-chain
- Ethereum payment from anywhere
- Ownership history can't be forged
How it shipped
- 01 · BRIEF
Title transfer is the bottleneck.
Cross-border title verification takes weeks of paper. Spec'd an atomic-swap pattern: payment + ERC-721 certificate transfer happen in a single Ethereum tx.
- 02 · BUILD
Hardhat contracts + Vite client + indexer.
Listing contract holds escrow + ERC-721, Mocha invariant suite covers the swap path. Express indexer mirrors on-chain state for fast catalogue queries · the marketplace UI never blocks on RPC.
- 03 · SHIP
Live on testnet · audit-ready paperwork.
Foundry-style coverage > 95%, threat model document, slither + mythril clean. Audit dossier handed back · production deploy is a customer call.
Stack
Contracts
Atomic listing + transfer
Single tx settles payment, escrow release, and ERC-721 transfer · partial-failure paths covered by tests.
Indexer
Express mirror of on-chain state
Off-chain catalogue queries hit the indexer, not the RPC · marketplace UI feels SaaS-fast despite running on-chain.
Provenance
On-chain ownership history
Every transfer is a public record · forging a paper trail isn't possible.
Tests
Mocha invariant suite + > 95% coverage
Suite covers the happy path, the partial-failure paths, and the adversarial paths · audit prep was light.
Case study
“Property transfers between countries used to take six weeks of paperwork. The studio built us a marketplace where the whole sale happens in one transaction, and the buyer gets a digital certificate on the blockchain that proves they own it, forever. The auditor signed off in a week. Buyers from outside the country can finally buy without flying in.”
More work
Next project
DField Lab