> For the complete documentation index, see [llms.txt](https://faisalaffan.gitbook.io/design-system/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://faisalaffan.gitbook.io/design-system/readme.md).

# README

<div align="center"><img src="/files/hhCCg5k9DAJl4ZPVUfUy" alt="banner" width="800"></div>

<div align="center"><img src="/files/XfteSDBwoVLCNhA6b8OG" alt="logo" width="200"></div>

Go monorepo implementing all 12 system design problems from Alex Xu's *System Design Interview* (2nd Ed), backed by theory from Kleppmann's *Designing Data-Intensive Applications*.

**100 tests | 44 packages | 12 services | 2 shared packages**

## What's Inside

| #  | Service             | Port | Core Pattern                  |
| -- | ------------------- | ---- | ----------------------------- |
| 1  | url-shortener       | 8080 | Base62 + collision retry      |
| 2  | rate-limiter        | 8081 | Sliding window + token bucket |
| 3  | chat-system         | 8082 | WebSocket rooms + broadcast   |
| 4  | notification-system | 8083 | Pub/sub + multi-channel       |
| 5  | unique-id-generator | 8084 | Snowflake 64-bit              |
| 6  | key-value-store     | 8085 | Consistent hashing sharding   |
| 7  | search-autocomplete | 8086 | Trie + top-K frequency        |
| 8  | news-feed           | 8087 | Fan-out on write              |
| 9  | web-crawler         | 8088 | BFS + politeness + dedup      |
| 10 | youtube             | 8089 | Metadata + search + transcode |
| 11 | google-drive        | 8090 | Files + folders + versioning  |

## Quick Start

```bash
go run ./services/url-shortener     # Pick any service
go test ./...              # 100 tests
go build ./...             # Build all
```