Building a Multi-Tenant SaaS with Rails 8

Rails 8 brings incredible defaults for building multi-tenant applications. Let's walk through the architecture.

Why Rails 8?

• Solid Queue replaces Sidekiq — no Redis needed
• Solid Cache for database-backed caching
• Solid Cable for WebSockets
• Built-in authentication generator

Tenant Isolation

There are two main approaches:

1. Shared database, separate schemas — using apartment or ros-apartment
2. Row-level isolation — with a tenant_id on every table

For most micro SaaS products, row-level isolation is simpler and more performant.

class ApplicationController < ActionController::Base
  include CurrentTenant

  before_action :set_tenant
end

Key Considerations

• Always scope queries to the current tenant
• Use database-level constraints for safety
• Cache per-tenant to avoid cross-tenant leaks

Rails 8's defaults let you focus on your product instead of infrastructure.