Is this a video course?

No. This is an interactive, slide-based learning platform. Each lesson has rich text, animated diagrams, live code editors, and quizzes. You learn by reading, interacting, and doing, not by watching videos passively.

How long do I have access?

Forever. Both pricing tiers are one-time payments with lifetime access. This includes all current 766 lessons and any future content we add.

What level of experience do I need?

None. We start from absolute basics like 'What is latency?' and build up to distributed consensus protocols. The Foundation level assumes zero prior knowledge of system design.

How much does the system design course cost?

7.99 US dollars for lifetime access globally, or 499 Indian rupees for lifetime access in India. One-time payment, no subscription, no hidden fees. 11 lessons are free with no signup required.

What technologies are covered?

Everything from DNS and load balancers to Kubernetes, Kafka, distributed databases, consensus protocols, stream processing, security architecture, and observability. We cover principles and real-world implementations used at Netflix, Google, Amazon, Uber, Stripe, and more.

Is this useful for system design interview preparation?

Yes. The lessons are structured around the exact topics asked in system design interviews at FAANG and top-tier companies. Interactive diagrams help you practice whiteboard-style explanations. Covers everything from URL shortener design to distributed payment systems.

How is this different from ByteByteGo or Educative?

766 interactive lessons (4x more than most competitors), 16 different diagram types that build step by step, real production examples from Netflix, Google, Amazon, Uber, and Stripe, and lifetime access for a one-time payment of $7.99 instead of annual subscriptions costing 100 to 200 dollars per year.

What happens when a request arrives during the refresh window in refresh-ahead caching?

The request gets the current (slightly stale) data immediately, and a background refresh is triggered, The defining characteristic of refresh-ahead is that the user never waits. The current cached data (still within its TTL) is returned immediately, while the cache asynchronously fetches fresh data in the background. The next request gets the refreshed data.

Why doesn't refresh-ahead refresh ALL cached keys proactively?

It only refreshes keys that are accessed during the refresh window, cold data expires naturally without wasting database queries, Refresh-ahead is demand-driven. A refresh is only triggered when a key is read during the refresh window. If nobody reads a key during that window, it simply expires. This is critical for efficiency, most caches contain thousands of keys, but only a small fraction are actively hot.

The HTTP Cache-Control directive 'stale-while-revalidate' is conceptually equivalent to:

Refresh-ahead caching, stale-while-revalidate tells the CDN or browser: 'serve the stale cached response immediately, and refresh from the origin in the background.' This is what refresh-ahead does, serve current data instantly while asynchronously fetching fresh data. CDNs like Cloudflare and Fastly use this extensively.

Refresh-Ahead Cache

Name: System Design Masterclass
Availability: InStock

in Caching Strategies

This lesson is part of the full System Design Masterclass. Unlock it along with 765 other lessons for a one-time payment.

One-time payment. Lifetime access. No subscription.

Global

$19.99$7.99/lifetime

One-time payment via PayPal

Get Lifetime Access

Foundation lessons free, try before you buy

Founders price, locked for the first 10,000 customers

India Special

India

₹999₹499/lifetime

One-time via UPI, cards, or net banking

Get Lifetime Access

Foundation lessons free, try before you buy

Founders price, locked for the first 10,000 customers

“The interactive diagrams alone are worth way more than the price.”

Anish K., Senior Engineer at a Bengaluru startup

All 766 interactive lessons

Step-by-step animated diagrams

Live code editors with real execution

Quizzes with instant feedback

Completion certificates per level

Lifetime access, all future content included

The first 5 Foundation lessons are free, no payment needed. Try them now