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Engineering Lab

Free · No account · Open source

A map of engineering knowledge you learn by doing. It is free, it needs no account, and PrepHike built it.

What it is

Engineering Lab takes the mechanisms engineers get asked about, the event loop, TCP, database indexes, closures and caching, and teaches each one the same way. The problem it solves first. The constraint that makes the problem hard. Then the mechanism, what it costs, and how it fails.

You do not read a definition and move on. You step a program through the call stack and the microtask queue and watch which one drains first. You drop a packet on a simulated link and see the sender work out that it went missing. You write the code, it runs in your browser, and the tests say whether you were right.

Why this sits next to PrepHike

PrepHike is about the search: the rounds you sit, what each one showed, and where you keep losing. It reads a debrief you wrote and tells you what it found.

What it will not do is teach you the thing you got wrong. Say a round went badly because you could not explain why a timer set to zero does not fire in zero milliseconds. No amount of tracking fixes that. Engineering Lab is where that part happens.

What it costs

Nothing. There is no account, no sign in and no payment. Open it and start.

Where your progress lives

In your browser, and nowhere else. Engineering Lab has no backend and no server to send anything to. Your answers, your scores and the topics you worked through sit in the browser's own storage on the machine you used. Clear that storage and they are gone, so there is a button that writes a backup file you keep.

That also means progress does not follow you between devices. That is a limit, not a feature. It is the price of having nothing to leak.

The code

Engineering Lab is open source under the MIT licence. You can read every line or run it yourself. You can also write your own topics for it. It reads learning packs written as JSON, and it builds the prompt that asks a model to write one.