Poets & Writers lists reliable contests, magazines, literary agents, and small presses under the "Publish Your Writing" tab.
Entropy's Where to Submit is a thorough list of presses, journals, anthologies, and residencies currently accepting work, updated quarterly.
Association of Writers and Writing Programs is a valuable source for creative writers in search of submission options (membership required).
Duotrope is a subscription-based website that helps writers find journals, publishers, and agents (membership required).
Writer Beware is a valuable source that investigates the legitimacy of literary agents, journals, and presses.
Think Check Submit assists researchers and writers in the evaluation of journals.
Submittable is a common platform used by publishers, magazines, and organizations. Make an account to manage your submissions!
The UT Research Guide on Predatory Publishing is a thorough look at unreliable open access publishers.