YOUR BRIEF
What to work through
Work through youTube as a spoken system design interview. Start by clarifying the scope, sketch a working design and explain the trade-offs behind your choices.
- Upload a video
- Stream a video on web, mobile and smart TVs
- Switch video quality as the network changes
- Resume an upload that was cut off
BEFORE YOU START
Constraints to discuss
- Uploads of tens of GB
- Playback starts fast, even on low bandwidth
- About 1 million uploads and 100 million views a day (Hello Interview)
- Availability over consistency
- Low delivery cost: CDN bills at about $0.02 per GB (Alex Xu)
Need a starting point?
Watch for these common gaps as you prepare:
- Uploading the whole file in one request with no way to resume
- Storing only the original and streaming it as is
- Serving video bytes from the API servers instead of a CDN
- Forgetting that transcoding is slow and must be asynchronous
Why this question is in the collection
These sources connect the problem to company interview reports or preparation guides. They do not guarantee what a company will ask you.
- Amazon: Fourth on Hello Interview’s list of the system design questions most asked at Amazon SDE II.
- Google: Aced’s Google guide lists "Design a video distribution service" and a Google-scale product such as YouTube among reported questions.
- Uber: Prepfully lists a recent Uber report: a video streaming architecture that handles varying network speeds.