| Version | Date | address | content |
| 10.0 | current: since Apr 12, 2015 | http://string-db.org/ | 9'643'763 proteins from 2031 organisms; 919'186'040 interactions. |
| 9.1 | Dec 27, 2013 to Apr 12, 2015 | http://string91.embl.de/ | 5'214'234 proteins from 1133 organisms; 332'235'675 interactions. |
| 9.05 | Mar 3, 2013 to Dec 27, 2013 | http://string905.embl.de/ | 5'214'234 proteins from 1133 organisms; 336'561'678 interactions. |
| 9.0 | May 29, 2011 to Mar 3, 2013 | http://string90.embl.de/ | 5'214'234 proteins from 1133 organisms; 224'346'017 interactions. |
| 8.3 | May 26, 2010 to May 29, 2011 | http://string83.embl.de/ | 2'590'259 proteins from 630 organisms; 89'236'924 interactions. |
| 8.2 | Oct 18, 2009 to May 26, 2010 | http://string-db.org/version_8_2 | 2'590'259 proteins from 630 organisms; 88'633'860 interactions. |
| 8.1 | June 14, 2009 to Oct 18, 2009 | http://string-db.org/version_8_1 | 2'590'259 proteins from 630 organisms; 84'076'989 interactions. |
| 8.0 | Nov 9, 2008 to June 14, 2009 | http://string.embl.de/version_8_0/ | 2'483'276 proteins from 630 organisms; 78'001'069 interactions. |
| 7.1 | Oct 19, 2007 to Nov 9, 2008 | http://string.embl.de/version_7_1/ | 1'513'782 proteins from 373 organisms; 38'573'579 interactions. |
| 7.0 | Jan 15, 2007 to Oct 19, 2007 | http://string.embl.de/version_7_0/ | 1'513'782 proteins from 373 organisms; 36'252'552 interactions. |
| 6.3 | Dec 12, 2005 to Jan 15, 2007 | - no longer available online - | 736'429 proteins from 179 organisms; 12'014'052 interactions. |
| 6.2 | June 26, 2005 to Dec 12, 2005 | - no longer available online - | 736'429 proteins from 179 organisms; 15'052'353 interactions. |
| 6.0 | Feb 20, 2005 to June 26, 2005 | - no longer available online - | 736'429 proteins from 179 organisms; 11'628'204 interactions. |
| 5.1 | July 30, 2004 to Feb 20, 2005 | http://string.embl.de/version_5_1/ | 444'238 proteins in 110 organisms; 17'804'284 interactions. |
| 4.0 | Sep 25, 2003 to July 30, 2004 | http://dag.embl.de/newstring_cgi/show_input_page.pl/ | 356'775 proteins in 110 organisms. |
| 3.0 | prior to Sep 25, 2003 | http://dag.embl.de:8080/newstring_cgi/show_input_page.pl | 261'033 proteins in 89 organisms |