System Design Interview
1. System Design Primer.
2. High Scalability Blog.
3. Book: Designing Data Intensive Applications.
4. Github Repository – System Design Interview.
Mock Interviews
1. Pramp – Peer to peer video calling with interview questions platform.
Data Structures & Algorithms
1. To help with visualization, VisuAlgo can be a great help.
Official Interview Preparation Guides
Know some other reliable resources (preferably free, open source)? Put them in the comments below and I will add it to the list for the community.