Backend Services

Overview

Web App projects include a Python FastAPI backend. The AI agent creates API endpoints, handles database operations, and manages server-side logic.

Backend Tab

The Backend tab has three sub-tabs:

• Logs — the backend's live output: Python stdout and stderr, FastAPI request lines, traceback frames. The server keeps the last 1000 lines; older output loads on demand rather than all at once
• API — the endpoints the backend exposes, with its schemas and services
• Database — the database browser for this project

Migrations live here too: the agent's schema changes appear as versioned migrations you can run or roll back, and seed data can be applied from the same place.

The backend runs on port 8080 inside the workspace.

API Proxy

The frontend proxy configuration routes /api/ requests to the backend automatically. No manual CORS setup needed.

What the AI Creates

When you describe backend features, the AI generates:

• FastAPI route handlers with proper HTTP methods
• Pydantic models for request/response validation
• Database models and migration files (when PostgreSQL is enabled)
• Error handling and logging
• Environment variable usage for configuration

Environment Variables

Backend environment variables are managed in the Environment tab:

• Set different values for Dev and Prod
• DATABASE_URL is automatically injected when PostgreSQL is enabled
• Custom variables are available via os.getenv() in Python code

Publishing the Backend

When you publish a Web App, the backend is deployed as a managed service. It's available at yourname.xaeio.app/api/ with automatic scaling.