Realclearpolitics.com has a list, with recent poll averages, of 6 battleground states..
Arizona
Florida
Michigan
North Carolina
Pennsylvania
Wisconsin
They need to update their list. Michigan? Really?

Fivethirtheight.com has a forecast page that lists the 9 closest states, updated at least daily..
Arizona
Florida
Georgia
Iowa
North Carolina
Ohio
Pennsylvania
Texas
Wisconsin
The snake chart on Fivethirtheight.com is an excellent way to take in the status of the race with a quick glance.

CNN's electoral vote map shows 6 battleground states, and they're not the same 6 as Realclearpolitics.com..
Arizona
Florida
Georgia
North Carolina
Ohio
Wisconsin

All three sources agree that the following 4 are swing states..
Arizona
Florida
North Carolina
Wisconsin

I'm not sure how they draw those conclusions. Every recent poll has given Biden a much bigger lead in Wisconsin than Trump has in Texas, where the polls are basically a dead heat. Yet Wisconsin is considered a swing state, and Texas is not. Texas is one of the closest states in the country. It should be on every list.

Here is something fun. If Trump wins all four of the agreed upon swing states, and the other states go based on recent polling -- Ohio and Georgia to Trump and Pennsylvania to Biden -- then the electoral vote count will be 268 to Biden and 268 to Trump, leaving Nebraska's 2nd Congressional District and Maine's 2nd Congressional District to decide. If those two districts split their votes, then it will be 269 to 269. In case of an electoral vote tie, the House of Representatives gets to decide the winner. But it's not a vote of all House members. Instead, it is one vote per state. And it is decided by the newly elected House that will take over in January, not the House members currently in office. In the event of an electoral vote tie, the House would probably give it the Republican because there are more states with Republican members of the House. The VP is decided by the Senate. It would be possible to have a President from one party and a VP from the other.