If in doubt about whether you may publish your scholarship online, go to SHERPA/RoMEO, an international listing of publisher copyright policies. Each entry provides a summary of the publisher's policy, including what version of an article can be published or archived, where it can be deposited, and any conditions that are attached to that deposit.
RoMEO Color Code
can archive pre-print and post-print or publisher's version/PDF
can archive post-print (ie final draft post-refereeing) or publisher's version/PDF
can archive pre-print (ie pre-refereeing)
archiving not formally supported
Open access publishers are typically more generous with author rights. The Directory of Open Access Journals (DOAJ) includes over 7,500 open access journals, browsable by subject.
The Confederation of Open Access Repositories (COAR) is a global association of repository initiatives with over 100 institutions from 35 countries. Its mission is to enhance the visibility and application of research outputs through a global network of open access digital repositories.
First Step) Consider checking a journal's copyright policy with the SHERPA/RoMEO Database:
Second Step) Know Your Rights As The Author:
If your article has been accepted for publication in a journal and you want it to have the widest possible distribution and impact in the scholarly community, make sure your publication agreement doesn't restrict you from online archiving.
According to the traditional (non open access) publication agreements, all rights —including copyright — go to the journal.
But if you want to include sections of your article in later works; give copies to your class or distribute it among colleagues; place it on your web page or in an online repository, then those goals are inhibited by the traditional agreement.
Learn more about how to have a balanced approach to copyright management by visiting this SPARC page. Then you will understand how adding an author addendum to your publisher's agreement can help fulfill your goals as an author.