The Green Papers has this very useful list of which candidates in each state are qualified to receive votes. Scroll down to find the list of states. Click on any state to learn which candidates are on the ballot for president, with their label, and also which presidential candidates who are not on the ballot have qualified to have their write-ins tallied.
Also, use this link to see all 51 jurisdictions at once, although this link doesn’t show the ballot labels.
The deadline for filing for write-in status still hasn’t passed in 15 jurisdictions. Generally The Green Papers has not yet listed the write-in candidates in those places, but will do so when the deadline has passed. For example, the California write-in filing deadline is October 25, so The Green Papers does not yet list the California write-in candidates. From other sources, it is known that Evan McMullin and Rocky De La Fuente have already qualified as a write-in for California, but the California Secretary of State will not release any information on the write-in list until October 28. Therefore the Green Papers will wait to update its page for California and other states in which the deadline hasn’t passed. The other such jurisdictions are Alaska, Connecticut, the District of Columbia, Kansas, Minnesota, Missouri, Nebraska, New York, North Dakota, Oregon, Virginia, Washington, Wisconsin, and Wyoming.
In a few instances, the states release the names who have filed, as they file, without waiting for the deadline, so The Green Papers has the list for a few states in which the deadline has passed, although obviously the list in those states may grow.