# Clients, APIs and services — System Design Interview Prep

Source: https://www.geekswithgeeks.com/en/system-design-interview/system-design-interview-06

> Use Clients, APIs and services to make a clear, evidence-based decision.

## Understand Clients, APIs and services

Start by naming the decision behind **Clients, APIs and services**. A strong answer explains the goal, the constraints, and the evidence you would use before acting. Do not treat a checklist as understanding: connect each step to the outcome it protects.

## Keep the workflow visible

Use this simple path while practising **Clients, APIs and services**: understand the situation, make one deliberate choice, then review the result.

![A four-stage workflow for Clients, APIs and services.](assets/figures/system-design-interview/section-2-map.svg) — Figure 2.1 — Decide, act, check and improve.

## A useful comparison

Think of **Clients, APIs and services** like planning a journey: a destination without a route is only a wish, while a route without a destination wastes effort.

Check the decision, not just the terminology.

**Quiz:** What is the most useful way to apply Clients, APIs and services?

- [x] State the goal, constraints and evidence before choosing an action.
- [ ] Copy a template without checking whether it fits.
- [ ] Use the most complex option first.

*Answer:* State the goal, constraints and evidence before choosing an action.. Good practice makes the reasoning visible, so you can review and improve it.