Exam prep where every question has a source

Problem

Exam prep lives or dies on trust. Question banks of unclear origin are common, and a wrong answer key costs people marks on the real exam. We wanted a focused study product for the AWS Certified AI Practitioner (AIF-C01) exam, without building a new app from scratch, and with content people could check.

What we built

• A third site on the platform behind Braineos and Finance Brain: mostly configuration, with its own database and sign-in.
• Locked premium content that stays visible: every course and lesson title shows, each exam domain has a free sample, and a single check gates the rest, so it behaves correctly before billing exists.
• A diagnostic quiz that needs no account and stores nothing: the browser scores it and shows per-domain results straight away.
• A Readiness page that scores each exam domain from spaced-repetition data the app already had, weighted the way the exam weights its domains, where one weak domain blocks “ready”. Building it exposed, and fixed, a bug that let cramming push cards to long review intervals.
• A course of 70 lessons and 300 practice questions weighted to the exam guide, where every item records its domain, task statement, difficulty and the AWS documentation page behind it, and retired services are never the right answer.
• An Android app from the shared mobile codebase, with progress in step with the web.

Result

CertBrain is live at certbrain.app and on Google Play. Its two new features, locked content and a sign-in-free diagnostic, work on every site on the platform, so the next product gets them for free.