Below is a division-by-division breakdown of the key free agents for all 30 clubs. Free agency begins when the clock strikes midnight ET on Monday night into Tuesday, when players can begin signing. Teams are listed in order of their division finish.
NATIONAL LEAGUE EAST
Key free agents: Mark Melancon, Wilson Ramos, Marc Rzepczynski, Chris Heisey, Stephen Drew, Matt Belisle, Yusmeiro Petit, Sean Burnett, Mat Latos
Two of the All-Stars who helped lead the Nationals to the NL East title are hitting free agency: Melancon, their Trade Deadline-acquired closer, and Ramos, their longtime backstop. Whether Washington pursues Ramos, who is reportedly seeking a four- or five-year deal, will be interesting, as he tore his right ACL in late September. Gio Gonzalez is coming off a rough year, but the Nats picked up his $12 million option, while declining Petit's.
New York Mets
Key free agents: Yoenis Cespedes (player opt-out), Bartolo Colon, Neil Walker, James Loney, Kelly Johnson, Alejandro De Aza, Jerry Blevins, Jonathon Niese, Fernando Salas
Cespedes, as expected, has reportedly opted out of his contract, so he'll become the best free-agent outfielder on the market. That doesn't preclude the Mets from re-signing him, just as they did last offseason. New York is also reportedly interested in bringing back Colon, who is 43 years old but was an invaluable member of the rotation in 2016 with the devastating rash of injuries to their electric young starters. The Mets picked up Jay Bruce's $13 million option on Thursday, despite his struggles after coming to New York via a Trade Deadline deal. New York declined to exercise Niese's $10 million option, electing instead to pay a $500,000 buyout.
Key free agents: Andrew Cashner, Fernando Rodney, Mike Dunn, Jeff Francoeur, Jeff Mathis, Chris Johnson, Dustin McGowan
The Marlins didn't exercise their club option to retain Rodney, the 39-year-old reliever who struggled in Miami after a dominant first half with the Padres, so he's a free agent. Starting pitching will be a top priority this offseason for a Marlins team looking to take the next step and make a run at the postseason, but Cashner appears to be a long shot to re-sign.
Key free agents: Ryan Howard, Jeremy Hellickson, A.J. Ellis, Andres Blanco, Peter Bourjos, David Hernandez, Charlie Morton
Howard's long tenure with the Phillies is at an end, as they declined his option, and the power-hitting first baseman will seek a fresh start elsewhere. Philadelphia expects to lose Hellickson, its Opening Day starter, to free agency, but the club will likely add another veteran pitcher to support a young pitching staff that will be a key to its success in 2017 and beyond. The Phils also declined their side of right-hander Morton's option.
Key free agents: A.J. Pierzynski, Eric O'Flaherty, Emilio Bonifacio
If Pierzynski isn't ready to retire just yet, the 19-year veteran catcher is free to seek out a new contract. The Braves are rebuilding around young cornerstones like Freddie Freeman, Julio Teheran and Dansby Swanson, and they don't stand to lose much to free agency.
AMERICAN LEAGUE EAST
Boston Red Sox
Key free agents: Koji Uehara, Junichi Tazawa, Brad Ziegler, Aaron Hill, Ryan Hanigan
First and foremost, the 2016 AL East champions will need to find a way to replace retiring superstar David Ortiz's sizable spot in the lineup. They'll also have a number of decisions to make in regards to their bullpen, with Uehara, Tazawa and Ziegler all set to become free agents. But the Red Sox's immensely talented young core -- and the veterans they're retaining -- have them poised to be strong contenders again next season, so they'll likely be active over the offseason to bolster their chances. Boston picked up Clay Buchholz's option ($13.5M) and declined Hanigan's ($3.75M) on the first day of free agency.
Toronto Blue Jays
Key free agents: Jose Bautista, Edwin Encarnacion, R.A. Dickey, Dioner Navarro, Michael Saunders, Jason Grilli (team option), Joaquin Benoit, Brett Cecil, Scott Feldman, Gavin Floyd
Bautista and Encarnacion, the faces of the franchise this decade, may have played their final games in a Blue Jays uniform. Toronto will extend qualifying offers to both, but the sluggers will almost certainly test the market. The Blue Jays could end up re-signing either of their all-world mashers, but losing one or both would be a big hole to fill for a team coming off back-to-back AL Championship Series appearances, and replacing them would become Toronto's top offseason priority.
Video: Atkins discusses the future of Bautista, Encarnacion
Key free agents: Mark Trumbo, Matt Wieters, Michael Bourn, Pedro Alvarez, Brian Duensing, Nolan Reimold, Drew Stubbs, Tommy Hunter, Steve Pearce
The Orioles' one-year deal with Trumbo paid off huge in 2016, and now the MLB home run champion, who hit 47 round-trippers, figures to command a lot of attention for his powerful bat. And Wieters could be the top free-agent catcher available due to Ramos' torn ACL. That means the O's might have to get busy in free agency if they want to make it back to the postseason after their 2016 Wild Card Game appearance.
New York Yankees
Key free agents: Mark Teixeira (retiring), Billy Butler
The Yankees have suddenly gained some financial flexibility this offseason, with Teixeira's retirement and their midseason trades of Aroldis Chapman and Andrew Miller. Their system is now stocked with prospects and talented young players, and it wouldn't shock anyone if the Yanks made some big splashes in free agency to become contenders again in 2017.
Tampa Bay Rays
Key free agents: Alexei Ramirez, Logan Morrison, Kevin Jepsen
Tampa Bay hopes to rebound from a third consecutive losing season and compete once again in the stacked AL East. The Rays are never a big-spending team in free agency, but their most important players aren't going anywhere, and they could always make some shrewd signings that fit into their budget.
Key free agents: Aroldis Chapman, Dexter Fowler (mutual option), Travis Wood, Chris Coghlan, Jason Hammel (team option), Trevor Cahill, Joe Smith
After winning the World Series, the Cubs will have some important decisions to make. Chapman will be the clear headliner of a strong class of free-agent relief arms, Fowler was an All-Star this season at a premier defensive position, and both could end up leaving in free agency. No matter what, though, Chicago will be loaded again next season, with four-fifths of its dominant rotationunder control and the lineup still filled with current and ascending stars.
St. Louis Cardinals
Key free agents: Matt Holliday (team option), Brandon Moss
The Cardinals are unlikely to pick up Holliday's option, which would make the veteran seven-time All-Star an enticing option for teams looking for an outfielder. The Cards' primary offseason focus might be improving defensively, especially up the middle -- run prevention was a main weakness for a club that just missed out on the postseason in 2016. St. Louis picked up its option on Jaime Garcia ($12M) on the first day of free agency.
Key free agents: Sean Rodriguez, Matt Joyce, Ivan Nova, Ryan Vogelsong, Neftali Feliz
The Pirates will have two rotation spots open with Nova, a Trade Deadline acquisiton from the Yankees, heading to free agency; Pittsburgh could try to re-sign Nova or add another starter. Joyce and Rodriguez's success in reserve/utility roles might earn them a bigger role elsewhere, so the Bucs might have to find players to fill their roles next season as they try to recapture their postseason form after a disappointing 2016.
Key free agents: Blaine Boyer, Chris Capuano
The Brewers have some solid young players at an array of positions, but they still appear to have a ways to go before they have a realistic shot at contention, so they might not try to make any big-ticket free-agent acquisitions. They won't be losing any key players, though, and they could look to add some complementary pieces alongside their up-and-comers and prospects.
Key free agents: Ross Ohlendorf, Alfredo Simon
Joey Votto and Brandon Phillips are still in Cincinnati, but over the last two seasons, the Reds have traded away All-Stars such as Bruce, Johnny Cueto, Todd Frazier and Chapman. As the rebuild continues, Cincinnati could seek out free-agent help for their lineup or rotation.
Key free agents: Mike Napoli, Rajai Davis, Coco Crisp (team option)
The AL champions picked up Carlos Santana's $12 million option the day after falling in Game 7 of the Fall Classic, so the team's biggest decision lies in whether to re-sign the 34-year old Napoli, who gave Cleveland a major boost with both his bat and his leadership in 2016. Davis and Crisp were also important pieces in the Tribe's World Series run, but most of the core of this team will stay in place.
Key free agents: Francisco Rodriguez (team option), Cameron Maybin (team option), Erick Aybar, Jarrod Saltalamacchia
The Tigers' first decisions after a 2016 campaign in which they fell just short of a postseason spot are whether to pick up options on center fielder Maybin and closer Rodriguez. They have potential replacements in their organization for both, but they aren't sure either outfield prospect JaCoby Jones or future closer Joe Jimenez will be ready for the big leagues right away.
Kansas City Royals
Key free agents: Kendrys Morales (mutual option), Edinson Volquez (mutual option), Luke Hochevar (mutual option), Peter Moylan, Drew Butera
Kansas City got a jump on its offseason decisions by picking up the options on Wade Davis ($10M) and shortstop Alcides Escobar ($6.5M) on the first day of free agency. The Royals might not be able to afford to bring back Morales, their starting DH, but general manager Dayton Moore hasn't ruled it out. With Kansas City reportedly hoping to scale back spending in 2017, it might have to pick and choose who it seeks to retain or go after.
Video: Moore on Morales, Royals DH position in 2017
Chicago White Sox
Key free agents: James Shields (player opt-out), Justin Morneau, Austin Jackson, Alex Avila, Matt Albers
Shields will reportedly not exercise his opt-out, keeping him in Chicago next season, but a few of the White Sox veterans are slated to become free agents, including Albers, who's option wasn't picked up by the club. This team started hot in 2016, but faded out of postseason contention, and Chicago might have to try to add some pieces if it wants to avoid another letdown next year.
Key free agents: Kurt Suzuki
Incoming chief baseball officer Derek Falvey will begin a new era for the last-place Twins, one of baseball's youngest teams. Improving their starting pitching will be a top priority in the offseason, and although the free-agent class doesn't offer many options, Falvey did help build the Indians' excellent rotation.
Los Angeles Dodgers
Key free agents: Kenley Jansen, Justin Turner, Rich Hill, Chase Utley, Josh Reddick, Carlos Ruiz (team option), Scott Kazmir (player opt-out), Joe Blanton, J.P. Howell, Brett Anderson, Jesse Chavez
The Dodgers won the NL West again in 2016 before falling in the NLCS, but they're about to have several marquee players hit free agency. Chief among those are closer Jansen, third baseman Turner and the resurgent Hill, all of whom will likely become top free-agent targets. The Dodgers have the money to re-sign key pieces or acquire new ones to surround Clayton Kershaw and superstar-in-the-making Corey Seager in order to contend again in 2017.
Video: Jansen, Utley among key offseason decisions
San Francisco Giants
Key free agents: Gregor Blanco, Angel Pagan, Sergio Romo, Santiago Casilla, Javier Lopez, Jake Peavy, Gordon Beckham, Joe Nathan
Many of the Giants' veterans from the team's recent World Series runs will become free agents this offseason, and players such as Romo, Lopez, Pagan and Peavy all seem likely to depart. The bullpen was one of the worst in the Majors in 2016, and it showed in their NL Division Series loss to the Cubs. San Francisco will have to address that heading into next season. San Francisco had an easy call on Matt Moore, and it picked up his $7 million option on the first day of free agency.
Key free agents: Mark Reynolds, Nick Hundley, Jorge De La Rosa, Boone Logan, Daniel Descalso, Ryan Raburn
A few Rockies regulars such as Hundley and Reynolds will be hitting free agency, but Colorado's stars are firmly under contract. With a lineup featuring Nolan Arenado, Carlos Gonzalez, DJ LeMahieu, Charlie Blackmon and Trevor Story and a young, up-and-coming pitching staff, the Rockies might target a piece or two as they look to contend in the NL West.
Key free agents: Daniel Hudson, Rickie Weeks Jr.
The D-backs have a new general manager, Mike Hazen, and he'll have to decide how to attack the free-agent market in his first offseason after Arizona's disappointing 2016. Even if Zack Greinke and Shelby Miller rebound and Paul Goldschmidt continues his All-Star production, the D-backs might need more.
San Diego Padres
Key free agents: Jon Jay, Edwin Jackson, Brandon Morrow, Clayton Richard, Adam Rosales, Carlos Villanueva
The Padres, looking to build around players such as Wil Myers, will have a lot of work to do heading into the 2017 season. San Diego has reportedly expressed interest in bringing back the respected veteran Jay, and GM A.J. Preller has also said he expects the organization to have an active offseason, especially in terms of trade discussions.
Key free agents: Ian Desmond, Carlos Beltran, Carlos Gomez, Mitch Moreland, Derek Holland (team option), Colby Lewis
The Rangers have a number of important decisions to make about players who propelled them to the AL's best regular-season record in 2016. Some of the team's biggest bats, such as Desmond and Beltran, are set to become free agents, and the fewer of them Texas has to replace, the better. On the starting pitching front, the Rangers will reportedly not pick up Holland's option, and whether to re-sign Lewis has been a major topic of discussion within the organization. Texas had an easy choice with Jonathan Lucroy, picking up its $5.25 million option for the catcher on the first day of free agency.
Key free agents: Adam Lind, Norichika Aoki (mutual option), Dae-Ho Lee, Franklin Gutierrez, Seth Smith (team option), Chris Iannetta (team option), Drew Storen
A Seattle club that fell just short of the postseason in 2016 has some decisions to make on a handful of complementary pieces. Players such as Lind, Aoki, Lee and Gutierrez aren't the team's superstars, but they got a lot of at-bats in 2016, and the Mariners will need players who can produce around Robinson Cano, Nelson Cruz and Kyle Seager next season. They may target defensive upgrades as well.
Key free agents: Colby Rasmus, Luis Valbuena, Doug Fister, Pat Neshek (team option), Jason Castro
With their talented young core intact, the Astros will likely seek starting pitching to help put them back in the postseason mix. Houston had a disappointing third-place finish this season after their postseason run the year before, but the team has the key pieces to get back with possibly a few upgrades. Fister and Rasmus might well depart in free agency, and Valbuena could too due to Houston's loaded core of position players.
Los Angeles Angels
Key free agents: Jered Weaver, C.J. Wilson, Yunel Escobar (team option), Tim Lincecum, Geovany Soto, Jhoulys Chacin, Andrew Bailey
The Angels should be fairly active this offseason, with much of their roster up in the air for the 2017 season. They still have the best player in the world in Mike Trout, Albert Pujols continues to produce and their rotation should be better with ace Garrett Richards slated to return from his partially torn right UCL. However, the Halos have major needs to address if they want to be a postseason team again.
Key free agents: Sam Fuld, Ross Detwiler
Operating on a small budget, the last-place A's are hoping their collection of young talent can take the next step in 2017. The Athletics aren't going to become instant contenders, but they could look to add a veteran in the rotation or an outfielder via free agency.
David Adler is a reporter for MLB.com based in New York. Follow him on Twitter at @_dadler. Matt Kelly is a reporter for MLB.com based in New York. Follow him on Twitter at @MattKellyMLB.