# API Gateway Patterns

> Design and use API gateways effectively for routing, cross-cutting concerns, and backend aggregation. Use when introducing or evolving an API gateway, BFF, or edge layer.

- Skill: `itsual/api-gateway-patterns` (Agent Skill)
- Install (CLI): `npx skillmds@latest add itsual/api-gateway-patterns`
- Raw SKILL.md: https://api.skillmd.com/api/skills/itsual/api-gateway-patterns/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: itsual (https://skillmd.com/u/itsual)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/itsual/api-gateway-patterns

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# API Gateway Patterns

## Overview

An API gateway can centralize cross-cutting concerns (auth, rate limiting, routing, observability) but can also become a bottleneck or single point of failure if misused.

## When to Use

- Multiple backend services need a unified external API
- You want to apply consistent policies at the edge
- Implementing Backend-for-Frontend (BFF) patterns

## Common Responsibilities

- Routing and path rewriting
- Authentication / token validation
- Rate limiting and quotas
- Request/response transformation
- Aggregation of multiple backend calls
- TLS termination and basic security headers

## Principles

- Keep business logic out of the gateway when possible
- Make the gateway highly available and observable
- Avoid turning the gateway into a distributed monolith
- Prefer standard protocols and well-supported gateway products

## Verification

- Cross-cutting policies are consistently applied
- Gateway is not a development bottleneck
- Failure modes of the gateway are understood and mitigated