> 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="https://2983881313-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FvOipblGYsQsvw021PJZx%2Fuploads%2Fgit-blob-2472c18dcfc20f4259ed2e0a1d2d2178f72a9794%2F01_BANNER.png?alt=media" alt="banner" width="800"></div>

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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
```