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, Handbook-cited 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 full 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 solutions. Worked solutions point 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 the current NCEES specifications — for PE Mechanical, the specifications effective October 2025.
See it for yourself.
Seven days, full access — exam-real practice, a grounded AI tutor on every problem, full-length mocks, and the diagnostic. No card.