About Plinth

Plinth is a focused study tool for the Claude Certified Architect — Foundations exam. It exists because passing this exam needs more than skimming docs: it needs reps on the exact pattern recognition the exam tests — orchestration vs. workflow, hooks vs. prompts, schemas vs. retries, the small handful of "which tradeoff did Anthropic pick" calls that decide ten or fifteen questions.

Built by John Ryu, an engineer who took the exam, found the prep landscape thin, and decided to build the tool he wished he'd had. The question pool, mock exam, weak-spot drill, and Compendium are all hand-curated against the published exam blueprint and refined from real test-taker debriefs.

Plinth is independent. It is not affiliated with or endorsed by Anthropic, PBC. Anthropic owns the Claude trademark and the exam; Plinth owns its question pool, explanations, and study aids. If Anthropic ever asks Plinth to take something down, Plinth will comply on the spot.

What's in the box

• 1,200+ practice questions across the five exam domains and 13 scenarios (6 official + 7 extended), with per-option rationales on the curated set.
• Two mock exam modes at the official domain weighting and time budget (120 minutes): Standard (4 of 6 official scenarios) and Comprehensive (4 of 13).
• Stem Decoder hints on every question — a 2-stage progressive disclosure (pointer → pattern reveal) keyed to a 17-section reference doc grounded in Anthropic's official Engineering posts, Claude Code docs, MCP docs, and the CCA-F exam guide.
• Weak-spot drill that builds a custom set from your own miss history.
• 493 flashcards with Leitner-style spaced repetition.
• Compendium & Stem Decoder reference docs — concept reference + pattern-match cheat sheet.
• Dashboard analytics including a "Where you used hints" widget that shows reliance by scenario × level (with Numbers ↔ Chart toggle).
• Bilingual — EN · 한국어 on questions, hints, and chrome.
• iOS and Android apps — native clients with cross-device sync. Your web purchase covers them when they ship.

What it isn't

• A brain dump or leak of real exam questions. Every question is original or derived from published Anthropic guidance.
• A pass guarantee. You still have to do the reps.
• A subscription. One-time purchase, lifetime access.

Feedback, corrections, and "your explanation on Q239 is wrong" notes are all welcome at support@plinthprep.com.