Stack Overflow
Q&A for professional and enthusiast programmers
Physics
Q&A for active researchers, academics and students of physics
Electrical Engineering
Q&A for electronics and electrical engineering professionals, students, and enthusiasts
The Great Outdoors
Q&A for people who love being outdoors enjoying nature and wilderness, and learning about the required skills and equipment
Server Fault
Q&A for system and network administrators
User Experience
Q&A for user experience researchers and experts
Code Review
Q&A for peer programmer code reviews
Substrate and Polkadot
Q&A for developers building blockchains with the Substrate SDK
Software Engineering
Q&A for professionals, academics, and students working within the systems development life cycle
Ask Different
Q&A for power users of Apple hardware and software
MathOverflow
Q&A for professional mathematicians
Arduino
Q&A for developers of open-source hardware and software that is compatible with Arduino
Ethereum
Q&A for users of Ethereum, the decentralized application platform and smart contract enabled blockchain
Chemistry
Q&A for scientists, academics, teachers, and students in the field of chemistry
History
Q&A for historians and history buffs
Mathematics
Q&A for people studying math at any level and professionals in related fields
Super User
Q&A for computer enthusiasts and power users
Worldbuilding
Q&A for writers/artists using science, geography and culture to construct imaginary worlds and settings
Personal Finance & Money
Q&A for people who want to be financially literate
Biology
Q&A for biology researchers, academics, and students
Cross Validated
Q&A for people interested in statistics, machine learning, data analysis, data mining, and data visualization
Information Security
Q&A for information security professionals
Artificial Intelligence
Q&A for people interested in conceptual questions about life and challenges in a world where "cognitive" functions can be mimicked in purely digital environment