Backend concept

Rate Limiting & Backpressure

Token buckets, quotas, fair usage, cost-based limits, retry storms, and abuse protection.

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Key takeaway

Token buckets, quotas, fair usage, cost-based limits, retry storms, and abuse protection. Start with the related games below when you want to turn the definition into practice.

Why this matters

Good limits protect shared backend resources without punishing normal users.

How to practice

Choose the limiting key that matches the expensive resource: IP, account, endpoint, job, or dependency.

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Learning objectives

Match rate limits to the resource being protected.
Distinguish per-IP, per-user, per-account, cost-based, and concurrency limits.
Use Retry-After, backoff, jitter, and circuit breakers to reduce overload.
Keep accepted work within bounded capacity.
Separate liveness from traffic readiness.
Reserve capacity for critical work during overload.

Common mistakes to avoid

Using only per-IP limits for authenticated or account-level abuse.
Applying the same raw request limit to cheap and expensive operations.
Relying on client-side debounce as the only protection.
Letting retries synchronize into a retry storm.
Using unbounded queues.
Failing liveness for dependency outages.

Games for Rate Limiting & Backpressure

Start with the first game, then use local review history to revisit missed decisions.

Scaling Intermediate

Rate Limit Architect

Choose rate limiting designs for realistic backend traffic patterns, from public APIs and login endpoints to queues, webhooks, and retry storms.

Time: 6-9 minutes
Concept: Rate limiting, fairness, backpressure, and abuse protection

Play Rate Limit Architect

Reliability Advanced

Overload Control Room

Control queue growth, adaptive concurrency, health probes, and priority-aware load shedding during overload.

Time: 9-12 minutes
Concept: Backpressure and overload control

Play Overload Control Room

Scaling Intermediate

Load Balancer Challenge

Route simulated traffic across backend servers using round robin, weighted round robin, least connections, and random strategies.

Time: 6-10 minutes
Concept: Load balancing strategies

Play Load Balancer Challenge

APIs Intermediate

Webhook Signature Forensics

Investigate webhook requests and choose safe handling for signatures, replay windows, retries, idempotency, and durable acknowledgement.

Time: 6-9 minutes
Concept: Webhook verification, replay protection, idempotency, and retry-safe processing

Play Webhook Signature Forensics