Tutorials System Design Tutorial
API Gateway Patterns — Complete Guide
API Gateway Patterns — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of System Design Tutorial on Toolliyo Academy.
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System Design Tutorial · Lesson 43 of 100
API Gateway Patterns
Basics ✓ → Scale → Interview
Scale · 2 — Distributed · ~6 min · Module 5: Microservices and Event-Driven Systems
What is this?
Gateway patterns include BFF (backend-for-frontend), aggregation, auth offload, and per-channel gateways for mobile vs web.
Why should you care?
ShopNest mobile may need fatter aggregated responses than the website without forcing every microservice to know mobile quirks.
See it live — copy this example
Sketch the architecture on paper. These lessons focus on concepts and trade-offs.
Mobile BFF: /m/home aggregates catalog + banners + cart count
Web BFF: thinner pages
Both still call domain services underneath
Do not hide a 10-service orchestration nightmare in one gateway method foreverRun Example »
This lesson uses terminal or setup steps. Run commands on your computer — the live editor appears on coding lessons.
What happened?
- BFFs tailor payloads per client.
- Aggregation reduces chattiness.
- Keep domain rules in domain services; BFFs adapt presentation.
Practice next
- Sketch a ShopNest mobile BFF endpoint.
- List which services it calls.
- Keep payment confirmation in Order/Payment domains.
- Split public vs partner gateways.
- Measure BFF fan-out latency budget.
Remember
BFF adapts clients. Domains keep the rules. Aggregate carefully.
Mobile home BFF
ShopNest app home uses one aggregated call.
Outcome: Fewer round trips on slow mobile networks.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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