The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Priorities (1 member)
- Production (1 member)
- Programming (115 members)
- Project Gutenberg (5 members)
- Project Management (2 members)
- Proofreading (4 members)
- Prototyping (2 members)
- Public diary (1 member)
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- Punctuation (4 members)
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- Quakerism (3 members)
- Queralbs (1 member)
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- RMS (1 member)
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- Radio (3 members)
- Rails Through the Bush (1 member)
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- ReStructuredText (2 members)
- Reading (59 members)
- Recommendations (1 member)
- Recording (3 members)
- Redaction (1 member)
- Reddit (2 members)
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- Releases (2 members)
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- Repositories (1 member)
- Requirements (1 member)
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- Resurgence Magazine (2 members)
- Reticulation (1 member)
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- Revision control (2 members)
- Revolution (2 members)
- Richard Flanagan (1 member)
- Richard Stallman (1 member)
- Right Ordering (3 members)
- Ripping (1 member)
- Robert Macfarlane (1 member)