About
Why we built CastorPrep
Most engineers who sit the PE pass — and the ones who don't usually miss for fixable reasons: prep that re-teaches what they already know, and never makes them work problems under a closed-book clock. We're engineers; we built the prep we wish we'd had — around the one thing that actually moves a score.
So we built it. CastorPrep is AI-native prep built on exam-real problem reps with a grounded tutor on every problem — at a price built for self-study. Everything included, no hype.
What we believe
Reps are the point. You pass by working problems — so practice is the core, and teaching happens on the problem in front of you.
We're the practice layer, not the lecture hall. Learning the material is one job; building the reps to pass is another. CastorPrep is built for the second — use it alongside a course, or on its own.
Rehearse the clock, not just the topics. A full-length, timed mock is how you find out you can finish in time — before exam day, not on it.
Grounded, not hyped. An AI tutor is only useful if you can trust what it says. Ours works from the verified worked solution — it explains a checked answer rather than improvising one.
Honest beats flashy. Specifics over testimonials you can't check. The best proof is trying it.
The name
Castor canadensis— the beaver — is nature's engineer: it reads a site, builds to the conditions, and its work holds. That's the standard we hold the product to. (No googly eyes required.)
Our content & originality standard
Our originality standard
The quality of an exam-prep product is the quality of its problems, so we hold a hard line on how ours are made:
Original, and built to one correct answer. Every problem is original to CastorPrep — built to exercise the engineering methods the exam tests, with a single defensible answer and a worked solution. A wrong solution is worse than no problem, so a correct answer is the bar every problem is built to.
Not copied or “reworded” from NCEES. We do not reproduce NCEES's own exam problems or the content of the NCEES Reference Handbook. Our problems are independently developed to exercise the same engineering methods the exam tests.
Handbook-cited where a citation exists. Where a problem carries a citation, the worked solution points you to the section of the NCEES Reference Handbook you'd use on the real closed-book exam — so you build navigation skill, not dependence.
Built to the current spec. Every exam we cover is built to that exam's current NCEES specification — for PE Mechanical and PE Electrical: Power, the specifications effective October 2025.
See it for yourself.
The whole practice bank is free with an account — exam-real problems, worked solutions, and the diagnostic. No card, and it doesn’t expire.