Once you've identified a test from a journal article, you might find the actual instrument through Google.
Use Google to find the test and to see if you can identify the rights holder.
If the test is commercially available, you may need to purchase rights to use the test.
If the test is unpublished (typically one that you have found in a journal article), you should contact the author of the article to seek permission.
The following are not databases of actual tests and measurement tools. Rather, they are databases of articles/studies that have used certain tests and tools.
Use some of the same search strategies that you would to find any journal article. To narrow your search to articles that include test or survey instruments, some additional strategies are listed with each database description below.