What it does
Rounds, with the preparation block attached to each
Revision scheduled backwards from the date
Time-zone handling that does not lose you an hour
Syncs with the tracker, so a moved round moves the prep
What it puts in front of you
A calendar that only holds dates is a worse version of the one you already have.
The round, with prep attached
A scheduled round is not a calendar entry, it is a deadline. The modules that cover what this company asks are pulled in front of it.
Revision, scheduled backwards
From the date, not from today. What you re-run the night before is a different list from what you start three weeks out.

Time zones that do not lose an hour
A remote loop crosses three of them and a recruiter's invite is usually written in theirs. The commonest way to miss a round is arithmetic.
Moves with the tracker
A rescheduled round drags its preparation with it. The two are the same record, not two places to keep the same date.
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Tracks, from the network to the negotiation
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Modules, each ending in a drill
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Systems worked end to end
The rest of it
The Curriculum — Free
Every layer, from a packet to a payment system
Design Drills — Free
Learn the trade-off by paying for it
Question Bank — Pro
The questions, and what a strong answer contains
Application Assistant — Pro
Drafts the application. Never sends it without you.
Interview Tracker — Pro
A pipeline built for loops, not for a spreadsheet
Community — Pro
Design reviews with people who will argue with you