Diffhall Hall Pass $1.95/moFree during preview
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Rooms

01Ask for work you can check 02Read the whole diff 03Keep secrets out of the code 04Treat every input as hostile 05Check who is asking 06Check that it exists 07Make tests able to fail 08Plan for when it breaks

Hall Pass $1.95/month or $19.50/year · one room $1.00 · Free during preview

About

A hall for one habit

Diffhall exists for people who build software by asking an AI to write it. It teaches one thing: read the work before you accept it.

What it is

Eight rooms, each a short reading that names its sources, and sixteen benches: an AI-written prompt, plan, diff, config file or test suite with problems planted in it. You tick the lines you would send back; Diffhall shows what you caught, what you missed and what you flagged that was fine. The material is fixed: written for this site and checked against the linked sources; no AI runs on the site and nothing you tick is sent to one.

What it is not

Diffhall is not a school or college, and vibecodecollege.com is only its address. There is no enrolment, no teacher, no degree, no credit, no grade on any record, no accreditation and no certificate. Nothing here counts toward a qualification, and Diffhall will not say otherwise.

It is not an app builder, a coding assistant or a security audit. A bench teaches you to spot a kind of problem; it does not check your own code.

Who runs it

Diffhall is run by WeldonPC (weldonpc.com), an IT services company in Ohio. It is independent: it is not affiliated with, or endorsed by, Vibecode or Not A Number Labs, DRVIBE, Inc. ("Vibe Code, Now"), Vibe Coding Academy, OWASP, MITRE or any AI company. Sources are linked so you can check them; their names are used only to cite them.

Accuracy

Facts in the rooms were checked on 2026-10-15 against the sources listed in each room. Library behaviour changes; when a room and a library's own documentation disagree, the documentation wins.