Definition
An API gateway is a single entry point that sits in front of your APIs. Every request comes to the gateway first, and it handles the shared work: checking who is calling, enforcing limits, and routing the request to the right service behind it. Instead of every service handling these chores on its own, the gateway does them once, for everyone, at the front door.
API gateways matter because modern systems are often made of many small services, and exposing each one directly would be messy and risky. A gateway gives you one controlled place to manage access, security, and traffic. This page explains what an API gateway does, how it works, the jobs it takes on, where it can become a bottleneck, and how it fits alongside the rest of your infrastructure.
What an API gateway does
An API gateway is the managed doorway to your APIs. Rather than letting callers reach each service directly, you point them at the gateway, and it decides what happens next: verify the caller, apply limits, then forward the request to the correct service.
Think of it like the front desk of a large building. Visitors do not wander straight to any office. They check in at one desk that confirms who they are and directs them to the right place. The gateway is that front desk for your APIs.
How a request flows through a gateway
When a request arrives, the gateway runs a series of checks before passing it on. It confirms the caller is allowed, applies rate limits, and may log the request and add or strip information. Then it routes the request to whichever service handles that job and passes the response back.
Because all traffic flows through one place, the gateway is also where teams add cross-cutting features once, like authentication or monitoring, instead of rebuilding them in every service. That central control is the main reason gateways exist.
The jobs a gateway takes on
Routing, sending each request to the right service behind the scenes.
Authentication, checking that the caller is who they claim to be.
Rate limiting, capping how often callers can hit your services.
Monitoring and logging, recording traffic so you can see what is happening.
Why teams put a gateway in place
A gateway simplifies a complex system. Instead of every service handling security, limits, and logging on its own, the gateway does it once at the entry point. That means less duplicated work, more consistency, and a single place to enforce the rules.
It also makes change safer. You can reorganize the services behind the gateway without callers noticing, because they only ever talk to the stable front door. That freedom to change the inside while keeping the outside steady is valuable as a system grows.
When the front door becomes a bottleneck
Because all traffic passes through it, a gateway is a single point that everything depends on. If it slows down or fails, every API behind it is affected. Teams address this by running gateways with redundancy so one failure does not take everything down.
A gateway can also grow into a tangle if too much logic is piled into it. Keeping it focused on shared concerns, rather than business rules that belong in the services, keeps it fast and maintainable.
API gateway vs load balancer
These two both sit in front of services, so they get confused, but they do different jobs. A load balancer spreads incoming traffic across copies of a service to handle volume and avoid overload. An API gateway is smarter about each request: it authenticates callers, enforces limits, and routes based on what the request is asking for. Many systems use both, with a load balancer handling raw traffic distribution and a gateway handling the per-request control.
Explaining infrastructure to technical buyers
Several companies Infrasity works with build API and infrastructure tools where concepts like gateways are everyday building blocks. Their buyers are technical and want to understand exactly how a tool fits into their setup.
Content that explains a concept like an API gateway in plain terms, and shows where a product fits in the flow, helps these companies reach the engineers who make adoption decisions, and builds trust through clarity.
Frequently asked questions
What is the difference between an API gateway and a load balancer?
A load balancer spreads traffic across copies of a service to handle volume. An API gateway controls each request, checking the caller, applying limits, and routing based on what is asked. They are often used together, handling different parts of the job.
Why not let callers reach services directly?
Because every service would then have to handle security, limits, and logging on its own, which is messy and error-prone. A gateway does that shared work once, at one controlled entry point, and lets you change the services behind it without affecting callers.
Is an API gateway a single point of failure?
It can be, since all traffic flows through it. Teams reduce that risk by running gateways with redundancy, so one failure does not take everything down. Kept focused and well-run, the benefits of central control outweigh the risk.
Related terms
API (Application Programming Interface), Rate Limiting, Authentication (Auth), Microservices, Provisioning