+9Design a rate limiterSystem designDesign a service that limits how many requests each API client can make. It sits in front of every API endpoint at high traffic.
Reported by 1 member · Last asked Oct 2026
#rate limiting
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Rate-limited Wikipedia crawler built with an AI assistantCodingWorking with an AI coding assistant (required in this round), build a crawler for Wikipedia that respects a rate limit. Its order follows a coverage rule: pages whose title starts…Last asked Sep 2026
+4Design a notification systemSystem designA shared service other teams call to send push, email and SMS notifications: templates, user preferences, retries, deduplication and rate limits.Last asked Sep 2026
+2Rate-limited event loggerCodingBuild a logger that rate-limits repeated events in a stream. Each event has a string name and an integer timestamp in seconds. Timestamps arrive in non-decreasing order, and…Last asked Sep 2026
Build and test a rate limiter with an AI assistantCodingIn a round where AI coding assistants are allowed, design and build a rate limiter from scratch. You choose the algorithm and the interface, use the assistant as you like, and…Last asked Sep 2026- Per-key fixed-window cost limiterCodingBuild a rate limiter that meters cost rather than request count. Each key may spend at most limit units in each fixed window of window seconds, with windows aligned to multiples…Last asked Sep 2026
+4Design a distributed rate limiterSystem designDesign a rate limiter that enforces a token-bucket limit per client across a fleet of servers. Cover where the limiter sits, where the bucket state lives (a shared store, local…Last asked Aug 2026- Design an ad frequency capping serviceSystem designDesign the service that decides, at ad-serving time, whether a user may see another ad from a campaign, so that caps like "at most 3 per user per day" or "exactly once" hold…Last asked Aug 2026
- Tiered rate limiter with limits that change at runtimeCodingBuild a rate-limiting service in Python. Each client belongs to a tier (for example free, pro, enterprise), and each tier has its own limit. A request arrives with a client id…Last asked Aug 2026
Design a token-based rate limiter for AI agentsSystem designAI agents call paid services, and each call spends billing tokens. Design a limiter that caps how many tokens each agent or customer can spend over time, enforces the cap across…Last asked Aug 2026
Design a to-do list service: CRUD, auth, rate limits, caching, versioningSystem designDesign the backend for a to-do list app: create, read, update and delete tasks, user authentication, rate limiting, caching, and versioning the API as it changes. Only the title…Last asked Jun 2026- +3Design a quota serviceSystem designTrack and enforce how much of each resource (API calls, storage, compute) every tenant may use, with fast checks and limits that stay accurate across regions.Last asked May 2026
Design per-user model usage quotas for a mobile appSystem designDesign how a mobile app enforces per-user quotas on model usage: how usage is counted, where the limit is enforced, what the app shows the user as they approach and reach it, and…Last asked May 2026- Per-user token bucket limiter with interval refillsCodingBuild a per-user token rate limiter for an AI API. Every user has their own policy, and one user's traffic never affects another's. A policy has three positive integers: -…Last asked Apr 2026
+1Pluggable hierarchical rate limiterCodingDesign a rate limiter with hierarchical limits (user, team, global) whose limit rules are pluggable without changing the core. Reported on 1point3acres' Cursor bank; reconstructed…Last asked Feb 2026
Design an AI gatewayAI system designDesign a gateway that sits between a company's services and the language-model providers they call. Cover routing requests across providers and models, failover, rate limits and…Last asked Feb 2026- Per-domain sliding-window rate limiterCodingA gateway receives requests one at a time, at most one per second. Each request names a domain. Build a rate limiter that keeps its state between calls and decides, for each…
+3Design a VM bandwidth rate limiterSystem designCap the network bandwidth each virtual machine in a cloud region may use, enforcing per-tenant limits across many hosts without adding latency to packets.