API Architecture

Document: 19-api-architecture.md
Version: 1.0.0

Purpose

This document defines the API architecture and integration standards used across all Rundown projects.

APIs provide communication between the frontend, Payload CMS, external services, and other application components. A consistent API architecture improves maintainability, security, scalability, and developer experience.

This document establishes how APIs should be designed, consumed, and maintained throughout Rundown applications.

API Philosophy

APIs represent business capabilities, not database tables.

Every endpoint should expose meaningful business functionality rather than simply mirroring the underlying database structure.

Well-designed APIs remain stable even when internal implementation changes.

Responsibilities

The API layer owns:

Data exchange
Business operations
Request validation
Response formatting
Authentication
Authorization
Error handling

Non-Responsibilities

The API layer should not own:

UI rendering
Database implementation details
Presentation logic
Infrastructure configuration

The API acts as a contract between systems rather than a user interface.

API Types

Rundown applications may use:

Payload Local API

Preferred when the frontend and Payload are part of the same application.

Benefits:

No HTTP overhead
Strong TypeScript support
Better performance
Simpler architecture

REST API

Preferred for:

Third-party integrations
Public APIs
Mobile applications
External services

REST endpoints should remain resource-oriented and predictable.

GraphQL

Supported only when project requirements justify it.

GraphQL should not be introduced solely because it is available.

Endpoint Design

Endpoints should represent business resources.

Examples:

/api/products

/api/orders

/api/contact

/api/newsletter

Avoid exposing internal implementation details.

Examples to avoid:

/api/getProducts

/api/updateTable

/api/databaseQuery

Request Validation

Every request should validate:

Required fields
Data types
Input format
Authorization
Business rules

Validation should occur before processing.

Response Structure

Responses should be:

Predictable
Consistent
Well-defined
Easy to consume

Every response should clearly indicate:

Success
Failure
Relevant data
Error details (where appropriate)

Sensitive implementation details should never be exposed.

Error Handling

Errors should be meaningful and consistent.

Typical categories include:

Validation errors
Authentication failures
Authorization failures
Missing resources
Server errors

Appropriate HTTP status codes should always be returned.

Authentication

Protected endpoints should require authentication before processing requests.

Authentication should be handled consistently across all protected resources.

Authorization

Every protected operation should verify permissions before executing business logic.

Never assume that authenticated users are authorized to perform every action.

Versioning

API versioning should only be introduced when maintaining multiple public API versions.

Internal APIs within a single application generally do not require versioning.

Avoid premature versioning strategies.

External Integrations

Integrations with third-party services should be isolated within dedicated service modules.

Examples include:

Payment gateways
Email providers
CRM platforms
Shipping providers
Analytics services

Frontend components should not communicate directly with third-party APIs unless explicitly required.

Performance

API performance should prioritize:

Efficient queries
Minimal payload sizes
Server-side caching where appropriate
Predictable response times

Avoid unnecessary requests and duplicated data retrieval.

Security

Every API should:

Validate input
Enforce authorization
Protect sensitive data
Use HTTPS
Sanitize user input
Limit exposed information

Security should be implemented consistently across all endpoints.

Documentation

Every externally consumed API should document:

Endpoints
Request format
Response format
Authentication requirements
Error responses

API documentation should remain synchronized with implementation.

Engineering Decision

API Strategy

Status: Accepted

Decision

Rundown applications should prefer Payload's Local API for internal communication and REST APIs for external integrations.

Reasoning

This approach:

Reduces unnecessary network overhead.
Improves TypeScript integration.
Simplifies architecture.
Supports scalable external integrations.
Avoids maintaining duplicate communication layers.

API Checklist

Before exposing a new endpoint, verify:

Does it represent a business capability?
Is input validated?
Is authentication required?
Is authorization enforced?
Are responses consistent?
Are errors handled appropriately?
Is documentation updated?

Summary

The API layer provides structured communication between application components and external systems.

By treating APIs as stable business contracts rather than simple database access points, Rundown applications remain secure, maintainable, and adaptable as business requirements evolve.

ADR-001: Repository Structure