Design a Component Library / Design System
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Interview answer templates and key talking points. Switch the mode in the header to change your experience.
Step 1 — Constraints
500+ engineers across 30 teams. Web, mobile, and documentation. Multiple products. How do you maintain consistency?
Step 2 — Decision: Monorepo vs Distributed repos
| Approach | Consistency | Autonomy | Friction |
|---|---|---|---|
| Monorepo (one source of truth) | High | Low | Low |
| Distributed (each team owns) | Low | High | High |
Winner: Monorepo. 30 teams need one source of truth.
Step 3 — Versioning strategy
Use semantic versioning: Major.Minor.Patch
Breaking changes = Major version bump. Document migration guide. Give 3 months notice.
Step 4 — Adoption metrics
Track: % of teams using latest version, time to migrate, bug reports per component.
If adoption is stuck, the component is probably not meeting needs. Invest in feedback.
Step 5 — Gotchas
Breaking changes without notice: Teams can't upgrade, fall behind.
No versioning: Chaos. Which version of Button does this team use?
Perfect design upfront: Teams don't use it because it doesn't match their needs.
Step 6 — Anti-patterns
Junior: Design in isolation from users. Result: Nobody uses it.
Mid: Try to make one component fit everyone. Result: Over-engineered.
Senior: Optimize naming before measuring adoption. Result: Premature.
Step 7 — 30-minute interview
0–5 min: "500 engineers, 30 teams, multiple products?"
5–15 min: Monorepo structure. Semantic versioning. Storybook docs.
15–30 min: "How do you drive adoption? Handle breaking changes?"
Step 8 — Interview simulation
Interviewer: "Design system for 500 engineers"
You: "Monorepo for one source of truth. Semantic versioning. Document each component: props, states, a11y, design tokens. Provide Storybook and migration guides. Track adoption: % using latest version, time to migrate. For major upgrades, provide codemods to reduce friction."
Interviewer: "Team wants to customize Button. What do you do?"
You: "Ask why. Might be a gap in the design system. Either add variants to Button, or document how to create a custom button using design tokens. Make customization possible, not the default."
Interviewer: "How do you prevent breakage?"
You: "Deprecate before removing. Announce 3 months before removal. Provide codemod for migration. Use feature flags in teams to control rollout."
Step 9 — Tiered answer
| Level | Time | What You Say |
|---|---|---|
| Junior (15 min) | Shared components, Storybook docs | |
| Mid (25 min) | Monorepo, versioning, migration guides | |
| Senior (30 min) | Adoption metrics, deprecation strategy, codemods |
Step 10 — Final checklist
| Issue | Solution |
|---|---|
| Consistency | Monorepo, semantic versioning |
| Documentation | Storybook, design tokens |
| Adoption | Track metrics, gather feedback |
| Breaking changes | Deprecate 3 months before, provide codemods |
| Customization | Design tokens first, custom components last |
| Governance | Design review for new components |
| Performance | Tree-shake unused components |
"Monorepo with semantic versioning. Document each component in Storybook with props, states, and design tokens. Track adoption: % of teams using latest version, time to migrate. For major upgrades, provide codemods and 3 months notice. For customization, use design tokens first—make it possible but not the default."