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BELGIUM · PROPTECH · WEB SAAS

AssetXtoken — PropTech tokenization across two markets

AssetXtoken is a Belgian PropTech startup enabling fractional ownership of real estate assets through blockchain tokenization. Our founding engineer led the technical build across both the investor-facing platform and the asset management backend.

Next.jsNode.jsTypeScriptPostgreSQLEthereum / ERC-20StripeAWS
2Markets served (BE + EU)
ERC-20Token standard implemented
< 8 wksFirst production deployment

The problem

Real estate investment in Belgium has traditionally required large capital commitments, locking most retail investors out of the asset class entirely. AssetXtoken's founding team wanted to change that by enabling fractional ownership: investors could buy tokenized shares of a property, receive proportional rental yield, and exit via a secondary market.

The technical challenge was significant. The platform needed four distinct systems working as one:

·A regulated investor onboarding flow (KYC/AML)
·A blockchain layer for token issuance and transfer
·A fiat payment rail connected to on-chain state
·A property management backend for the asset side

All of it had to comply with Belgian financial regulations and remain extensible to broader EU markets — MiCA regulation was on the horizon at the time of the build.

The architecture

Investor portal
Next.js (App Router, TypeScript)
Admin backend
Next.js + tRPC
Database
PostgreSQL (Supabase)
Token layer
Ethereum (ERC-20) + Hardhat
KYC/AML
Sumsub integration
Payments
Stripe (fiat on/off-ramp)
Blockchain bridge
Custom Node.js event listener
Deploy
Vercel (frontend) + AWS ECS (backend)

The most architecturally complex element was the bridge between Stripe payment events and on-chain token issuance. When an investor completes a fiat payment, the system must verify the payment, check KYC clearance, compute the correct token quantity, issue tokens to the investor's wallet, and update the PostgreSQL ledger — atomically, with full rollback on any failure.

We designed this as an event-driven pipeline with idempotency keys at every step, ensuring no double-issuance even on network failure or a retried Stripe webhook.

The outcome

AssetXtoken launched to Belgian investors within eight weeks of engagement start. The first property was tokenized and funded within two weeks of launch. The investor onboarding flow — KYC, fiat payment, token receipt — takes under ten minutes end to end.

The architecture was reviewed by AssetXtoken's legal counsel as part of their MiCA compliance preparation. The event log and audit trail design was cited as aligned with the regulation's record-keeping requirements.

What we'd do differently next time

KYC integration was underscoped in the initial discovery. Sumsub has substantial edge-case behaviour around document rejection and re-submission flows that is not apparent from their API documentation. We would allocate a full sprint to KYC flows in future regulated builds.

We would also start on a Layer 2 — Polygon or Arbitrum — rather than Ethereum mainnet. Gas cost predictability matters more to a PropTech user than mainnet credibility, and an L2 bridge migration is far harder than an upfront L2 decision.

Building in a regulated market?

We have shipped production software across five regulatory environments. Talk to us about your compliance requirements before writing a line of code.

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