dc=tools
logonHours is 21 bytes, one bit per hour of the week in UTC. Paste a value or drag on the grid, and the time zone conversion is done for you. Everything runs in your browser, so nothing you paste leaves your machine. The page's Content-Security-Policy also stops it from sending anything, which you can check in its source.
Paste hex, base64 from an LDIF export, escaped bytes, or the 21 numbers PowerShell prints. Or click a cell, or drag across a block of days and hours.
The attribute holds one bit per hour of the week in UTC, Sunday first, so the grid shifts when you change the time zone above. Daylight saving moves the allowed hours by an hour in local time, because the stored hours don't change. If your offset isn't a whole number of hours, the grid rounds it, since logonHours can't store half hours.