| Website | Founded | Closed | Description/focus | Languages available | Copyrighting of user contributions | Registration required? |
Price |
| Answers.com | 2005 | — | All topics | English | | Free |
|
| Ask.fm | 2010 | — | Social topics | 49 languages | | Yes |
|
| Askbot | 2009 | N/A | varies | varies | | varies |
|
| Ask MetaFilter | 2003 | — | Many topics | English | All posts are copyright to their original authors.[1] | No to browse, yes to contribute |
|
| Avvo | 2006 | — | Legal | English | | Yes |
|
| Baidu Knows | 2005 | — | Many topics | Chinese | | No to browse, yes to contribute |
|
| BlikBook | 2010 | N/A | Local academic | English | | Yes |
|
| Blurtit | 2006 | — | All topics | English | | Yes |
|
| Brainly | 2009 | — | Academic | 12 languages | Contributed content owned by its author(s) | No to browse, yes to contribute |
|
| Brilliant.org | 2013 | — | Science, technology, math | English | User retains ownership; Brilliant can use, distribute, modify.[2] | Yes/Paid[3] |
$599.99 for life time use |
| ChaCha | 2006 | 2016 | Many topics | English | Owned by ChaCha[4] | N/A |
|
| Chegg | 2005 | — | Academic | English | Owned by Chegg Inc.[5] | Yes / paid |
|
| eNotes | 2005 | — | Academic | English | Owned by eNotes.com[6] | Yes / paid |
$14.99/month; $49.99/year[7] |
| Experts-Exchange | 1996 | — | Information technology | | | Yes / paid |
|
| Fixya | 2005 | — | Consumer products | English | | Yes |
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| Google Answers | 2002 | 2006 | | English | | Yes |
|
| Google Questions and Answers | 2007 | 2014 | Many topics | Russian, Chinese, English, French | | N/A |
|
| Gutefrage.net | 2006 | — | | German | | Yes |
Free |
| HealthTap | 2011 | — | Health information | English | | No |
|
| Internet Oracle | 1989 | — | All topics (humorous) | English | | No |
|
| Jelly | 2013 | 2017 | All topics | English | | |
|
| Knowledge IN | 2002 | — | Many topics | Korean | | |
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| LinkedIn Answers | 2007 | 2013 | Business | | | Yes |
|
| MadSci Network | 1995 | — | Science | English | | |
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| Mahalo.com | 2007 | 2014 | Many topics | English | | N/A |
|
| Ответы@Mail.Ru | 2006 | — | | Russian | | |
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| ProfNet | 1992 | — | Journalists | English | | Yes |
|
| Quora | 2009 | — | Many topics | 22 languages | Contributions owned by the author. Quora granted "worldwide, non-exclusive, royalty-free license" to content use, distribution, or modification.[8] | Yes, except to view single answers |
Free |
| Reddit | 2005 | — | All topics | Depends on subreddit | | No to browse, yes to contribute |
|
| Sharecare | 2009 | — | Health and wellness | English | | No |
|
| Spring.me (formerly Formspring) | 2009 | 2015 | All topics | English | | Yes |
|
| Stack Exchange | 2008 | — | Many topics | English (Q&A about other languages takes place in those languages as well as English) | Contributions owned by the author. Contributions "perpetually and irrevocably licensed to Stack Exchange under the Creative Commons Attribution Share Alike license".[9] | No to browse and answer, yes to ask and contribute fully. Some topics allow asking as a guest. |
|
| Stips |
2006 |
— |
All topics |
Hebrew |
|
Yes |
|
| The Straight Dope | 1973 (print) | 2018 | Many topics | English | | No |
|
| Transtutors | 2007 | — | Academic | English | Owned and operated by Transweb Educational Services[10] | Yes / paid |
|
| TXN (The Experts Network) | 2011 | ? | Sports | English | | No |
|
| Uclue | 2007 | 2017 | Many topics | English | | Yes |
|
| WikiAnswers | 2002 | 2018 | Many topics | | Subsumed by Answers.com (one of several concurrent URLs) | |
|
| English Wikipedia Reference Desk | 2004 | — | Many topics | English | CC-BY-SA 3.0 and GFDL dual license | No |
|
| Yahoo! Answers | 2005 | 2021 | All topics | 13 languages | Contributions owned by the author. Yahoo retains rights to the use, distribution or modification.[11] | No |
|
| Zhihu | 2011 | — | Many topics | Chinese and a few others | Owned and operated by the original authors. | Yes, except to view answers of questions when directed from search engine |