The peculiar cruelty of web application architecture mistakes is the delay between cause and consequence. A poor architectural decision made in week two doesn't cause problems in week three. It causes problems in month eight, when growth demands something the architecture wasn't designed to support.

Mistake 1 — Mixing Frontend and Backend Logic

In a Bubble application built without discipline, business logic accumulates in the frontend. The principle: business logic belongs in the backend — Supabase functions, database constraints, row-level security policies. The frontend is responsible for presentation and user interaction. This separation means adding a mobile frontend later doesn't require rebuilding business logic.

Mistake 2 — Choosing a Backend for the Wrong Reasons

The right criteria: supports your data structure, scales to your eventual load, gives control and portability, accessible to your team, replaceable if necessary. Supabase addresses all of these: PostgreSQL handles complex data structures, scales to significant volumes, is open-source (portable), has a developer-friendly interface, and can be accessed directly by developers working outside the Bubble layer.

Mistake 3 — Ignoring Authentication from Day One

Authentication shapes data model decisions. Supabase's built-in authentication integrates directly with its row-level security system — access control enforced at the database level, not the application level. Set this up from day one and design the data model with user-level security in mind.

Mistake 4 — Building Without an API Layer

Without a clean API layer, each new client (mobile app, third-party integration, admin tool) requires understanding the internals of the original application. Using Supabase's auto-generated API means adding new clients is additive rather than architectural.

Mistake 5 — Treating the Database as a Detail

Database design is the foundation on which everything else is built. For PostgreSQL in Supabase: define foreign key relationships explicitly, use appropriate data types, index frequently queried fields, design the schema to support upcoming features. Spend a week on schema design before touching the application.

Mistake 6 — No Strategy for Automation and Integration

n8n provides a single, visible home for all automation and integration logic. Every workflow is documented. Failures are logged and alertable. New workflows can be added without touching the application layer. The principle: automation belongs in n8n, not in the application.