About fivenines

Why this exists

fivenines was built by engineers coming from companies like Uber and Redis. We spent years working on systems that handled millions of requests per second: distributed caches, real-time pipelines, infrastructure that had to stay up. The work taught us something most learning resources still miss: real understanding comes from building the mechanism, not just reading the explanation.

When we looked at what was available to engineers who wanted that understanding faster, we found the same problems everywhere: materials that were either too shallow to be useful, too narrow to give you the full picture, or entirely passive. Read this. Watch that. None of it forces you to model the runtime path yourself.

The best way to learn technical content is to try to apply it yourself. That is not a novel insight — it is how every engineer we have respected actually learned. But there was no product that took that principle seriously end-to-end: short theory, practice checks, D2 modeling, and feedback on what your model gets right or misses.

fivenines is that product. We started with Build Your Own Redis because Redis is both approachable and deep: command execution, protocol parsing, event loops, persistence, replication, failover, and cluster sharding all show up in one real technology.

Why this matters now

The role of AI in software development is changing fast. Copilot and its successors are genuinely good at generating boilerplate, CRUD, and syntax — the commodity layer of engineering. That layer is getting thinner.

What AI cannot do for you is build the mental model underneath the abstraction you use every day. You still need to know why an event loop stays responsive, why replication can lose recent writes, why a hash table resize can hurt latency, and what a cluster redirect really means.

The engineers who will thrive are the ones who understand what is happening underneath the abstractions they rely on. fivenines is designed to build that understanding through structured practice, not passive consumption.

We built fivenines because we believe the next decade of software will reward engineers who can reason from first principles, debug across layers of the stack, and make decisions that AI tools cannot make for them. The curriculum reflects that philosophy: depth over breadth, practice over passive learning, and real feedback over generic explanations.

The team

fivenines is built by a small team with deep experience in distributed systems and infrastructure at scale.

The company

fivenines is operated by Firebrick Labs EOOD, a software company registered in Bulgaria. We are a small team that believes in building focused tools that do one thing extremely well. Rather than chasing feature sprawl, we focus on depth: the tutorials, practice checks, and D2 modeling problems on this platform are designed to build real understanding, not surface-level familiarity.

Our name comes from the “five nines” (99.999%) availability target that many infrastructure teams aim for — a reminder that the systems we teach about are not theoretical. They are the same systems that power the services you use every day, and the same tradeoffs that engineers at Uber, Redis, and similar companies face.

Firebrick Labs EOOD
UIC / BULSTAT: 208431638
31 Alexander Malinov Blvd., Mladost 1A
Mladost District, Sofia 1729, Bulgaria

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Email: team@firebricklabs.com

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