While it is preferable to publish in journals that are open and accessible, that may not always be possible. However, most times you can make a copy of your work free to access by depositing a copy in a repository. Open access content in repositories often includes peer-reviewed content (publisher's version or post-prints) as well as pre-prints, the version of an article before it underwent peer review.
There are thousands of journals, but some journals and publishers are more open than others; some are hybrid offering select articles as open, while others are less open. Here is a diagram from SPARC that details the range of options you might have available to you depending on where you published.
To help you understand what you can share and where you can share it, SHERPA/roMEO is a useful database. This database hosts a journal's or a publisher's default policy on self-archiving.
Additionally, the SPARC Author Addendum is a contract that you may be able to use in negotiating your rights as an author.
Below are common places where you may want to post or share your paper. Be sure to review your rights and restrictions before posting and sharing.
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