Kimai supports tagging timesheet records, which allows you to create arbitrary logical structures, which can be used to filter records in exports/invoices and reports.
Kimai supports two tagging modes:
The mode can be switched in the Settings screen in the Theme section (there is a checkbox).
There is a tag administration screen, which displays all available tags and the counter how often they are used.
The action menu for each tag allows you to filter all records for the choosen tag, by linking to the team timesheet with a preset tag filter.
When a tag is deleted, only the tag and all links to it are deleted. The linked timesheet records are NOT touched.
You can query for a free search term, which will be searched in the fields:
name