Devntech client · Belgium · Co-livingLive

Colochousing

A Belgian co-living platform with 16K+ users, moving from a legacy Rails app to a new multi-tenant TypeScript platform. I was part of the team behind the move, and I built across the new platform, the Coloc resident app and the Rails side that kept both in step.

Role
Full-stack engineer, web and mobile
Client
Colochousing, Belgium
At
Devntech, Nov 2025 to 2026
Platforms
Web, iOS, Android
Stack
TypeScript, Fastify then Hono, oRPC, TanStack Start, Drizzle, PostgreSQL, React Native, Rails 7
The Coloc resident app, live on the App Store and Google Play. Select any screen to view at full size.
16K+users on the platform
24K+rental applications
65houses in 8 cities
400+residents on the Coloc app
01

The product

Colochousing is a co-living company in Belgium with 65 houses in 8 cities. Its platform serves 16K+ users and has handled more than 24,000 rental applications, and residents use the Coloc app for events, tasks, split bills and rent.

The web platform and the API behind the app ran on a long-running Rails app. While I was at Devntech, the team was moving them onto a new multi-tenant TypeScript platform, one part at a time, with the Rails app still live behind it.

02

The new platform

legacyRails 7 appWeb app, REST API, Sidekiq
new platformMulti-tenant TypeScriptHono, oRPC, TanStack Start, Drizzle
marketplace data synced nightly · resident pages moving over one by one

The new platform is a modular TypeScript monorepo with its own apps for admins, the public marketplace and residents. The Rails app stays live behind it while each part moves over.

  • An API that started on Fastify and moved to Hono, with oRPC procedures that also publish an OpenAPI spec
  • TanStack Start apps for the admin dashboard, the public marketplace and the resident community
  • Modules for properties, rentals, billing, the marketplace and the migration itself
  • PostgreSQL through Drizzle, and background jobs on BullMQ
  • Organizations for multi-tenancy, and sign-in with passkeys, magic links and two-factor authentication
  • A nightly sync from the Rails app that skips listings whose checksum has not changed
03

What I built

Platform

Moving to multi-tenant TypeScript

I built pieces on both sides of the move: the Rails APIs the new platform syncs from, marketplace pages on the new stack, and access control scoped to each organization.

  • Rails sync APIs that the nightly job pulls marketplace data from
  • Marketplace pages rebuilt in TanStack Start
  • Access checked against the active organization, its membership and the member's role
  • TypeScript
  • Fastify
  • Hono
  • oRPC
  • TanStack Start
  • Drizzle
Mobile

The Coloc resident app

I built features across the React Native app, live on the App Store and Google Play for 400+ residents, and shipped them through EAS.

  • Events and tasks
  • Split bills and rent payments
  • Push notifications
  • EAS releases to both stores
  • React Native
  • Expo
  • TypeScript
  • EAS
Legacy

The Rails app during the move

I also worked on the Rails 7 app and its REST API, with React on Rails, ERB and Sidekiq, while it stayed live during the move.

  • Rails 7
  • React on Rails
  • Sidekiq
  • PostgreSQL
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