Stack Overflow
Q&A for professional and enthusiast programmers
Ask Ubuntu
Q&A for Ubuntu users and developers
Area 51
Q&A for proposing new sites in the Stack Exchange network
Ask Different
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Skeptics
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Portuguese Language
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Space Exploration
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Science Fiction & Fantasy
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Code Golf
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Reverse Engineering
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Database Administrators
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Mathematics
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Worldbuilding
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Earth Science
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Photography
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Information Security
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Android Enthusiasts
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Writing
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Cryptography
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Bicycles
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Arqade
Q&A for passionate videogamers on all platforms
English Language Learners
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Woodworking
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Puzzling
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English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Physics
Q&A for active researchers, academics and students of physics
Unix & Linux
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Software Engineering
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User Experience
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Electrical Engineering
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Game Development
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Blender
Q&A for people who use Blender to create 3D graphics, animations, or games