ExamCert is a free exam-prep website and mobile app for people working toward IT certifications. It covers roughly a hundred exams from AWS, Microsoft, CompTIA, Cisco, ISC2, ISACA and Google Cloud, and every exam page breaks down the official domains, their weightings, the question format and the passing score, so you know where to spend your study time before you book the test.
Main site: https://www.examcert.app/
Practice questions come with a full explanation for each option, not just the right letter, and the app tracks weak domains so you can drill the topics you keep missing. Timed mock exams follow the real blueprint, and everything works offline on iOS and Android.
A couple of popular starting points:
CompTIA Security+ prep: https://www.examcert.app/exams/comptia-security-plus-sy0-701/
ISC2 CISSP prep: https://www.examcert.app/exams/cissp/
Good fit for beginners going for a first cloud or security certification, and for experienced engineers who want a quick structured review before exam day.