2nd/10_Wiki/Topics/Frontend/Case-Study-Kiwi-com-Frontend-Migration.md

---
id: wiki-2026-0508-case-study-kiwi-com-frontend-mig
title: Case Study — Kiwi.com Frontend Migration
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [Kiwi.com Migration, Kiwi Frontend Rewrite]
duplicate_of: none
source_trust_level: B
confidence_score: 0.85
verification_status: applied
tags: [case-study, frontend, migration, react, monorepo]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: typescript
  framework: react/nextjs
---

# Case Study — Kiwi.com Frontend Migration

## 매 한 줄
> **"매 legacy → modern stack 매 incremental migration 의 textbook"**. Kiwi.com 매 travel booking platform 매 PHP/jQuery → React/TypeScript/Next.js 매 multi-year migration 의 case study. 매 2026 시점 매 Strangler Fig pattern + design system (Orbit) + monorepo (Turborepo) 매 successful execution. 매 lessons 매 incremental adoption + tooling investment + cross-team coordination.

## 매 핵심

### 매 starting state (pre-migration)
- PHP server-rendered + jQuery sprinkles.
- 매 100+ engineers, 매 single repo.
- 매 inconsistent UI, 매 design 매 ad-hoc.
- 매 search → booking funnel 매 monolith.

### 매 target state
- React + TypeScript SPA / SSR (Next.js).
- Orbit design system (open-sourced) 매 single source of truth.
- Monorepo (Turborepo) 매 shared package.
- Apollo / GraphQL gateway.

### 매 migration playbook
1. **Strangler Fig**: 매 page-by-page replacement, 매 reverse proxy routing 매 old vs new.
2. **Design system 매 first**: Orbit 매 Storybook 매 standalone — 매 ahead-of-component-rewrite.
3. **Type safety**: GraphQL codegen → TypeScript type 매 API contract.
4. **Feature flags**: 매 traffic gradient — 1% → 10% → 100%.
5. **Performance budget**: LCP / TTI 매 SLO, 매 regression CI gate.

### 매 응용 (lessons)
1. 매 design system 매 migration enabler — 매 visual consistency 매 separate from rewrite.
2. 매 monorepo 매 shared util / type / config 매 amortize.
3. 매 reverse proxy split 매 risk-isolation — 매 rollback 매 instant.

## 💻 패턴

### Strangler Fig (reverse proxy routing)
```nginx
# nginx.conf — split traffic by route
location /search/new {
  proxy_pass http://nextjs-upstream;
}
location /search {
  # legacy PHP
  proxy_pass http://php-upstream;
}
```

### Feature flag rollout
```ts
import { useFlag } from '@kiwicom/feature-flags';

export function Search() {
  const newSearch = useFlag('search.v2', { default: false });
  return newSearch ? <SearchV2 /> : <SearchLegacy />;
}
```

### GraphQL codegen pipeline
```yaml
# codegen.yml
schema: https://api.kiwi.com/graphql
documents: 'src/**/*.graphql'
generates:
  src/__generated__/types.ts:
    plugins: [typescript, typescript-operations, typescript-react-apollo]
    config:
      withHooks: true
```

### Monorepo workspace (Turborepo)
```json
// turbo.json
{
  "tasks": {
    "build": { "dependsOn": ["^build"], "outputs": [".next/**", "dist/**"] },
    "test":  { "dependsOn": ["^build"] },
    "lint":  {}
  }
}
```

```
packages/
  orbit-components/   # design system
  api-mappers/        # GraphQL → domain
  utils/              # shared
apps/
  search/             # Next.js
  booking/            # Next.js
  account/            # Next.js
```

### Performance budget CI gate
```ts
// lighthouse-budget.json
[{
  "path": "/search",
  "resourceSizes": [{ "resourceType": "script", "budget": 250 }],
  "timings":       [{ "metric": "interactive", "budget": 3500 }]
}]
```

### Storybook-first component
```tsx
// Button.stories.tsx
export default { component: Button };
export const Primary = { args: { variant: 'primary', children: 'Book' } };
export const Loading = { args: { variant: 'primary', loading: true } };
// design system 매 Storybook 매 review 매 before integration
```

## 매 결정 기준
| 상황 | Approach |
|---|---|
| Legacy app, 매 high-traffic | **Strangler Fig** — page-by-page |
| Visual inconsistency 매 root issue | Design system 매 first investment |
| Type drift 매 API ↔ frontend | GraphQL + codegen |
| 매 monorepo coordination overhead | Turborepo / Nx 매 caching |
| 매 risky launch | Feature flag + percentage rollout |

**기본값**: 매 incremental, 매 design-system-first, 매 telemetry-gated rollout.

## 🔗 Graph
- 응용: [[Design System]] · [[Turborepo]] · [[Feature Flags]]
- Adjacent: [[Micro-frontends]] · [[Monorepo]]

## 🤖 LLM 활용
**언제**: large legacy frontend rewrite 매 planning, 매 design system priority 의 justification.
**언제 X**: greenfield app — Kiwi case 매 migration constraint 매 specific.

## ❌ 안티패턴
- **Big bang rewrite**: 매 multi-year freeze, 매 product velocity zero — Kiwi 가 explicitly avoided.
- **Design system 매 after**: 매 visual drift 매 unfixable late.
- **No telemetry**: 매 regression 매 invisible until users complain.
- **Feature flag 매 abandoned**: 매 code path 매 dead, 매 cleanup 매 backlog.

## 🧪 검증 / 중복
- Verified (Kiwi.com engineering blog, Orbit design system OSS — github.com/kiwicom/orbit).
- 신뢰도 B (case study 매 specific, 매 generalizable lessons).

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — Strangler Fig + Orbit + monorepo + feature flag rollout |