What this is
melreus documents Rectangle on macOS in the depth its users actually need: the failure modes and their real causes, and the large set of behaviours configurable only through the preference domain. It exists because that material is scattered, and because a great deal of what circulates about it online is stale.
How it is written
Preference keys and their accepted values are taken from the project's own terminal command documentation, which is the authoritative source. Failure modes are drawn from the public issue tracker and reproduced where possible. Where a claim depends on a specific macOS version or hardware configuration, that is stated rather than generalised.
Where a page disagrees with the upstream documentation, upstream is right and this site is out of date. Preference keys are added and occasionally changed between releases.
What this is not
It is not affiliated with, endorsed by or connected to the Rectangle project, Knollsoft, or Apple. It is not a support channel for the application — bugs and feature requests belong on the project's own issue tracker, where the people who can act on them are. Nobody pays for coverage, and nothing here is sponsored.
Corrections
macOS changes and so does the app. If a page here is wrong, say so — corrections are made quickly, and noted where they materially change the advice.
Start with the diagnostic
If something is broken right now, this is the fastest route to a cause.
Open the diagnostic →