Practice series
Abuse, rate limits & policy control
Rate limits, bot mitigation, fraud, moderation, policy enforcement, and scoped access.
- 01Preview
AI Agent System
Design a production AI agent application platform that accepts user goals, manages context and memory, calls tools safely, pauses for human review when needed,...
Practice bank - 02Preview
Coupons and Deals Platform
Design a coupons and deals platform where users browse and search a large, frequently changing catalog of deals and redeem coupon codes exactly once per limit,...
Practice bank - 03Preview
Flash Sale
Design a flash sale system where a limited quantity of a hot item goes on sale at a fixed instant and receives a 1000x traffic spike in seconds — inventory must...
Practice bank - 04Preview
Moderation Service
Design a content moderation pipeline that screens user-submitted posts/media for policy violations, balancing posting latency against review accuracy at platfor...
LinkedIn - 05Preview
Spend Management System
Design a corporate spend management platform like Brex or Ramp — every card swipe must be authorized or declined against a live policy engine in under two secon...
Brex - 06Preview
Ticketmaster (General Admission)
Design Ticketmaster for general-admission events — there is no seat map, only a fixed capacity count per ticket tier, and the system must sell tickets correctly...
Ticketmaster - 07Preview
Webhook
Design a webhook delivery platform (Stripe-webhooks-style) that reliably delivers event notifications to thousands of third-party consumer endpoints under retry...
Stripe - 08Preview
MCP Tool Gateway
Design an MCP-style tool gateway that lets AI agents discover and invoke enterprise tools (CRM writes, ticketing, internal APIs) safely, with per-user authoriza...
Anthropic - 09Free
- 10Preview
- 11Preview
Fraud Detection
Design a real-time ML fraud/risk scoring system that scores payment transactions in under 100 ms.
Stripe - 12Preview
LLM Guardrails Pipeline
Design a guardrails pipeline that wraps an LLM application with layered input and output safety.
NVIDIA / Meta - 13Preview
Online Judge
Design a LeetCode-style online judge that safely runs untrusted user code at scale.
Google / Amazon