System Design Capstones

Why this module exists

You learn system design by building and critiquing real systems. These capstones are full designs with explicit trade‑offs and measurable decisions.

Capstone 1: Global News Feed

Focus:

• Fanout models (write vs read)
• Cache strategy for hot feeds
• Consistency vs freshness

Key question: What happens when a user with 10M followers posts?

Capstone 2: Real‑Time Ride Dispatch

Focus:

• Geo indexing + matching
• Latency budgets for dispatch
• Surge handling

Key question: What is the matching latency at peak traffic?

Capstone 3: Video Streaming Platform

Focus:

• CDN + edge caching
• Storage tiers
• Multi‑bitrate encoding

Key question: Which tier absorbs sudden traffic spikes?

Capstone 4: Analytics Pipeline

Focus:

• Stream vs batch
• Exactly‑once trade‑offs
• Backfill and reprocessing

Key question: How do you correct bad data after the fact?

How to Use These

For each capstone:

1. Write requirements + constraints.
2. Draw a 1‑page architecture.
3. Identify top 3 failure modes.
4. Re‑design for scale.