What Kind of Platform Is Netflix?

Netflix is a subscription video-on-demand platform, shortened to SVOD, delivered over the internet as a client-server system. Technically it is a distributed system that runs on Amazon Web Services, built from hundreds of microservices, with its own content delivery network called Open Connect that stores video inside internet providers' networks.

That one paragraph answers the three ways people ask this question. As a business, Netflix is an SVOD service. As a network type, it is client-server over HTTPS, not peer-to-peer and not broadcast. As a software system, it is a cloud-based microservice architecture with a private CDN.

Netflix as a type of platform

The media industry calls Netflix an over-the-top service, shortened to OTT, meaning video delivered over the open internet rather than through a cable or satellite operator. Within OTT it is SVOD: a flat monthly fee for unlimited viewing, with an advertising-supported tier added later. It is not a marketplace, a social network, or a live broadcaster, although it streams some live events.

Netflix is also a cloud service in the plain sense. It owns no data centers for streaming. Every part of the service other than video delivery runs on rented AWS capacity, which is why "is Netflix cloud based" has a simple yes as the answer.

The parts of the Netflix system

A distributed, cloud-based system

A distributed system is one whose parts run on many machines and talk over a network. Netflix runs across several AWS regions, so a failure in one region shifts traffic to another. The control plane, meaning everything that is not the video bytes, scales up and down with demand by adding or removing servers.

Netflix pioneered testing this by breaking it on purpose. Chaos Monkey turns off random servers in production during working hours so that engineers find weak points before an outage does.

A microservice architecture

A microservice architecture splits an application into small services that each own one job and are deployed on their own. Netflix's services handle sign-in, subscription state, the catalog, playback licensing, and the personalization that fills each row of your home screen.

Netflix deploys these services through Spinnaker, its open source delivery tool, and runs them in containers on Titus, its container platform that now runs on Amazon EKS. Service discovery, the way one service finds another, uses Eureka.

Video delivery through Open Connect

Video does not come from AWS. When you press play, the Netflix control plane picks the best Open Connect appliance for your connection and hands your device a list of URLs. Your device then downloads the video in small segments over HTTPS.

Netflix uses TCP, not UDP, and does not use WebRTC. Playback is adaptive: each title is stored at many quality levels, and the player switches between them every few seconds based on your measured bandwidth. That is why quality drops during congestion instead of the video stopping.

Netflix does not publish how many servers it runs. Open Connect appliances are placed at internet exchange points and inside individual internet providers, and Netflix offers them to providers at no charge because local delivery lowers both parties' costs.

How the recommendation system fits

Personalization is a separate set of services fed by the data pipeline. Viewing events flow through Kafka into Flink and Spark jobs, models are trained in Python, and the results are stored where the home-screen service can read them in a few milliseconds. The artwork shown for a title is also personalized, chosen per user from several options.

Why interviewers ask about Netflix

Netflix is the standard example for the split between a control plane on general cloud servers and a data plane on a CDN. When an interviewer asks you to design a streaming service, they expect you to separate those two, choose a database per access pattern, and explain adaptive bitrate. Netflix's public writing lets you check your answer against a real system.

How to Prepare

• Learn the building blocks first. Grokking System Design Fundamentals explains CDNs, caching, load balancers and database choices in order.
• Then practice the full streaming case. Grokking the System Design Interview walks through the trade-offs interviewers score.
• Work the Netflix design question step by step. See designing a Netflix-like streaming service.
• Read how the API layer works. See does Netflix use an API.
• Interviewing at Netflix? Start with Netflix's interview process for software engineers.