On average, each MLB team currently has about six arbitration eligible players. I count 188 in total, from the White Sox and Astros with two each to the Giants with a dozen. This winter, arbitration eligible players are those with at least two years and 146 days of MLB service and less than six years, who aren't signed to multiyear deals.
Tonight at 11pm central time, teams must decide whether to tender contracts to their arbitration eligible players. Perhaps 20% of arbitration eligible players are at risk of being cut loose (non-tendered) tonight. Of course, reaching free agency without having to accrue six years of service can sometimes be a positive. Also, note that each year there are a few stray non-tenders who are not yet arbitration eligible, such as Alfredo Aceves last year.
We'll have posts for non-tenders in each league constantly updated today, but another great way to stay informed is MLBTR's non-tender tracker. There you can see all the arbitration eligible players and filter by team and whether the player was tendered a contract. Be sure to bookmark our non-tender tracker and check it throughout the day.