What is an API gateway?

An API gateway is a server that sits between clients and backend services, acting as the single entry point for all API requests. Instead of clients calling ten different services at ten different URLs with ten different authentication methods, they call one gateway. The gateway handles routing, authentication, rate limiting, request transformation, and response aggregation.

If backend services are departments in a company, the API gateway is the front desk. Every visitor (request) checks in at the front desk. The front desk verifies their identity, directs them to the right department, and ensures no single visitor overwhelms any department with too many requests. Unlike generic AI automation posts, this guide shows real CodeWords workflows — not just theory.

Kong, one of the most widely deployed API gateways, reports processing billions of API transactions monthly. Gartner's 2025 API Management report identified API gateways as critical infrastructure for organizations with more than 50 internal and external APIs. As the number of APIs grows — the average enterprise now manages 15,000+ APIs according to Salt Security — gateways become essential for maintaining order.

Related: API authentication methods explained, REST API vs GraphQL, what is a workflow engine, microservices vs monolith explained, OAuth 2.0 flow explained, CodeWords integrations, CodeWords templates.

What an API gateway does

An API gateway handles several cross-cutting concerns that would otherwise need to be implemented in every backend service.

Request routing. The gateway reads the incoming request (URL path, headers, query parameters) and forwards it to the appropriate backend service. /api/users goes to the user service, /api/payments goes to the payment service. Clients don't need to know where services live or how many instances are running.

Authentication and authorization. The gateway validates API keys, JWT tokens, or OAuth 2.0 credentials before the request reaches any backend service. Invalid credentials get rejected at the gate — backend services never see unauthenticated requests.

Rate limiting. The gateway enforces request quotas — 100 requests per minute per API key, for example. This protects backend services from being overwhelmed by a single misbehaving client. Rate limiting at the gateway is more efficient than implementing it in every service individually.

Request/response transformation. The gateway can modify requests before forwarding (add headers, transform body format) and responses before returning to the client (filter fields, aggregate from multiple services). This enables API versioning without changing backend code.

Load balancing. When a backend service runs multiple instances, the gateway distributes requests across them. Round-robin, least-connections, and weighted strategies are common.

API gateways and automation platforms

Every automation platform is, at some level, an API gateway for your workflows. When CodeWords receives a webhook or scheduled trigger, it routes the request to the correct workflow, handles authentication, and manages execution. The gateway pattern is embedded in the platform's architecture.

For builders, API gateways matter in two scenarios:

Consuming APIs. When your workflow calls external APIs (Stripe, Salesforce, Google APIs), the target service likely sits behind an API gateway. Understanding this helps you debug issues — a 429 (rate limited) response comes from the gateway, not the service. Retry with exponential backoff. CodeWords handles retries automatically for its 500+ integrations.

Exposing APIs. If your automation needs to receive requests from external systems (webhooks, custom API endpoints), CodeWords generates FastAPI endpoints that serve as lightweight gateways — validating incoming data, routing to workflow logic, and returning structured responses.

Popular API gateways

Cloud-native gateways like AWS API Gateway, Google Cloud API Gateway, and Azure API Management integrate tightly with their respective cloud ecosystems. They offer managed scaling, built-in monitoring, and IAM integration. Best when your services already run on that cloud provider.

Open-source gateways like Kong, Traefik, and APISIX run anywhere — cloud, on-premises, or containers. Kong offers a plugin ecosystem for custom authentication, transformation, and logging. Traefik excels in Kubernetes environments.

Automation-embedded gateways within platforms like Zapier, Make, and n8n abstract gateway functionality behind visual builders. You don't configure rate limits or routing rules — the platform handles it. CodeWords provides gateway functionality within its serverless execution layer, giving you the benefits without the infrastructure management.

When you need an API gateway vs. when you don't

You need one when: you have multiple backend services, you need centralized auth and rate limiting, you want API versioning without backend changes, or you're exposing APIs to external consumers who need a stable interface.

You don't need one when: you have a single backend service, you're building internal-only tools, or your automation platform already handles routing and auth for you. Most builders on CodeWords never need to deploy a separate API gateway — the platform's webhook endpoints and integration layer serve that role.

Build API-powered workflows at codewords.agemo.ai — check templates for common patterns and pricing for execution costs.