Does Netflix use an API?

Yes. Netflix runs almost entirely on APIs. Hundreds of internal microservices talk to each other through them. Every device reaches the backend through an edge gateway. Partner hardware integrates through private APIs.

This answer covers the APIs inside Netflix and how they evolved. If you want to know whether you can build an app on a public Netflix API, see Is there any API for Netflix? instead. The short version is that the public API was retired and there is no open replacement.

The API layers at Netflix

Layer	What it does	Who calls it
Edge gateway	Routes, authenticates, and shapes every incoming request	Phones, TVs, browsers, consoles
Service to service	Carries calls between internal microservices	Netflix services only
Device and partner	Lets TV makers and consoles embed the app	Approved hardware partners
Open Connect	Controls how video files are placed and served	Netflix and partner ISPs

The API redesign that made Netflix famous

Netflix started with one generic REST API. Every device called the same endpoints and got the same resource shaped responses.

That design created a problem the Netflix engineering team named chattiness. Building one home screen took many separate calls. Each call returned only a small slice of what the screen needed. A TV with a slow connection paid for every round trip.

The team rewrote the API. Device teams could now define what one screen needed and fetch it in a single request. Instead of the API dictating the shape, each client described its own shape. That idea later became public as Falcor, and the same problem is what GraphQL was built to solve.

This history is worth knowing, because it is the clearest real world example of a general lesson. A resource shaped API is easy to design and hard on clients with many screens and slow networks.

The edge gateway

Every request from a device hits a gateway before it reaches any service. Netflix built Zuul for this job, then rewrote it as Zuul 2 on a non blocking design that holds far more concurrent connections per instance.

The gateway does the work that should not be repeated in every service:

Routing. It maps a request to the service that can answer it.
Authentication. It checks the caller before the request goes deeper.
Traffic shaping. It applies rate limits, retries, and load shedding.
Failure isolation. It can fail one route without taking the app down.

For the detail on the gateway itself, see Which API gateway does Netflix use?.

Service to service APIs

Behind the gateway sit hundreds of services, each owning one job: user profiles, recommendations, playback authorisation, billing, search, viewing history.

They call each other through APIs rather than sharing a database. That boundary is what lets a team deploy its service without coordinating with everyone else. It is also what makes contracts matter so much. A field removed without warning breaks the callers, not the owner.

Netflix uses REST widely for these calls, alongside gRPC for paths where a strict schema and a binary format pay off.

What happens when a service fails

A request that crosses ten services can fail in ten places. Netflix made failure handling part of the API layer rather than a per team afterthought.

Two ideas do most of the work.

Circuit breakers. A caller tracks how often a downstream service fails. Once failures cross a threshold, the caller stops sending requests for a while and fails fast instead. This stops one sick service from tying up threads across the whole system. Netflix built Hystrix for this, and the pattern outlived the library.

Fallbacks. When a call fails, the caller returns something useful rather than an error. If the recommendation service is down, the app shows a generic popular list. The screen still renders. Most users never notice.

Design an API so a fallback is possible. An endpoint that returns one all or nothing blob leaves the client no choice but to show an error page.

From Falcor to federated GraphQL

Falcor solved the shape problem for one client at a time. It did not solve the next one, which is that many teams each own a slice of the same screen.

Netflix later moved to a federated GraphQL layer. Federation means each team publishes the part of the schema it owns, and a gateway stitches those parts into one schema for clients. A device asks for a screen. The gateway splits that into calls to the owning services and assembles the answer.

The pattern is worth naming in an interview. It is what you reach for when many teams serve one screen and you do not want a shared team owning the whole contract.

Device and partner integration

Netflix ships on thousands of device models: smart TVs, streaming sticks, consoles, phones, browsers. Each one runs a client that talks to the same backend through private APIs.

Backward compatibility is treated seriously for one reason: those clients. A television bought years ago may never be updated again. If the API changes the shape of a response, that device stops working, and the owner has no fix available.

This is the single best example to reach for when an interviewer asks why versioning matters.

Open Connect and delivery

Video bytes do not come from the same place as the metadata. Netflix built Open Connect, its own content delivery network, and places appliances inside internet service provider networks.

APIs decide which copy of a file a device streams, and from which appliance. Adaptive bitrate streaming then adjusts the quality as the network changes, so playback continues instead of stopping to buffer.

What interviewers take from this

Netflix comes up in interviews as the setting for four separate questions.

Gateway design. What belongs at the edge, and what belongs in the service.
Response shaping. How to serve many device types without many round trips.
Backward compatibility. How to change an API when some clients never update.
Delivery. How the metadata path and the video path differ.

Naming which of the four you are answering is usually worth more than the answer itself.

Frequently asked questions

Does Netflix use REST APIs?

Yes, widely, for internal service to service calls and for device traffic. It also uses gRPC where a strict schema and a binary format pay off. And it built Falcor so a client could request the exact shape a screen needs.

What API gateway does Netflix use?

Zuul, and its rewrite Zuul 2. The gateway handles routing, authentication, rate limiting, and failure isolation for every request that enters the system.

Why did Netflix redesign its API?

The original generic REST API forced devices to make many calls to build one screen. That was slow on televisions and slow connections. The redesign let each device team define what one screen needed and fetch it in a single request.

Can I use the Netflix API in my own app?

No. The public API was retired, and access now goes through partnership agreements. Third party catalogue sources are the usual alternative for hobby projects.

How does Netflix keep old devices working?

By treating backward compatibility as a hard requirement. Fields are added, not removed or renamed, and old response shapes stay supported, because a television bought years ago may never receive another update.

Is Netflix a microservices architecture?

Yes. Hundreds of independent services each own one job and communicate through APIs rather than a shared database, which lets teams deploy on their own schedule.

How to prepare

Practice the design, not the trivia. Interviewers use companies like Netflix as the setting for an API design question, not a quiz. Grokking Modern API Design Interview covers the same ground as a design problem: gateways, partner contracts, versioning and backward compatibility, and rate limits.

Get the distributed systems background. Grokking the System Design Interview covers the caching, replication, and delivery pieces that sit under all of this.