These are all the links used in the 2021 Bracket Matrix.
Tier 1 (3+ years in the matrix, above average)
The Bracket Project
1-3-1 Sports
The 17th Seed
Bazinga Bracketology
Boiling the Bracket
Bracketball
Bracketology Corral - Bill Riccette
Bracket Bros
The Bracket Mensa
Brackonomics
Bracksketblogs
Bucky's Bracket
Busting Bracketologists - CJ
Drew's Bracketology
Graham Doeren Bracketology
Head vs. Gut
Heat Check CBB
Hoops HD - Jon Teitel
Inside the Hall
Ivar's Blog
Jabesblog
Jason Wells' Bracketology
KY Brackets
Kyle Foster's Bracketology
MAG
Making the Madness
March Madness 2020
M+J's Bracket Watch
Mondays are for Bracketology
No Perfect Bracket
Nothing but Nylon
Oak Creek's March Madness
Prime Time Bracketology - Grant Hansell
Random Bracket Blog
Razorbrackets
RFS Bracket Science
RSN Bracketology
Selje's Bracketology
Spidey's Bracket
Stuck in 1977
Syracusefan7's Bracketology
WNUR Sports
Best Damn Bracket Period
Bracketville
Bracket Brad's Big Board - @NoisyHuevos
Bracket Forecast - Rusty Tutton
Bracket WAG
Busting the Bracket - Jeff Borzello
The Catch and Shoot
CBS Sports - Jerry Palm
D Ratings
Delphi Bracketology
Elam Seeding Predictions (M-Sports Fans)
ESPN - Joe Lunardi
Facts and Bracks
Gade Pool
Haslametrics
Heat Check CBB - Lukas Harkins
Hindertology
Jason Lisk Bracketology (Team Rankings)
Lobofan2003's Bracketology
One Man Committee
Pulse on Sports - Kevin Pulsifer
RaleighWX Bracketology
Rocco Miller's Bracketology
RotoWire BracketZology - Adam Zdroik
Ruckles Bracketology
SB Nation - Chris Dobbertean
Sporting News - Ryan Fagan
Stadium - Tim Krueger
The Steelers n'at
Tier 2 (1-2 years in the matrix, above average)
Bauertology
Bracket Beyond
Crazy Sports Dude
From the Rafters
Full Court Press
Hardwood and Hollywood
TheNightVenom
Seanny P Bracketology
seeding68
Sluder Bracketology
The Truth's Bracketology
Anthony's Blog
Bracketometry
Cardinaldave's Bracketology
Connor Groel's Bracketology (Top Level Sports)
Devils Digest - Jeff Griffith (Formerly Sideline Intel)
DPI Bracketology
The Game Haus
Isaac Perrigo's Bracketology
NCAA.com - Andy Katz
Robo Macketology
Ryan Tures Bracketology
The Stats Guru
Tier 3 (3+ years in the matrix, below average)
Aidan's Bracketology
Beef's Bracketology
Blacketology
Bracket Predictions
Bracketville USA
Bracks on Bracks
Brad-ketology
Carolina Sports Thoughts
Deuce 2 Sports
Eye on the Tournament
G Money's Sports Page
HoopsHD
ncaabracketology
Regan NCAA Tournament Index
Tier 4 (1-2 years in the matrix, below average)
The BIG Heartland Bracketology (formerly JGood)
BracketBot
Bracket Prophet
Bracket Racket
Bracketology Busters
Busted Bracketology
CBB Review
Cracked Sidewalks
Heartbreak City
Let Me B-Frank
Logan's Sports Ratings
Made for March
The Pi-Rate Ratings
The Athletic - Brian Bennett
Bracket Bingo
Crossroads Sports
Deceptive Speed
The Geek's Bracketology
INCC Stats
Radio.com - Jordan Schwartz
Recspecs730 - Luke Benz (formerly YUSAG)
Streaking the Lawn
Tier 5 (New to the matrix)
Harrison Bracket
Jacob Larson's Bracketology
Last Word on Pro Basketball
Mad About March
Mark Stouffer's Bracketology
MRFSF68
Skarmory's Bracketology
Teacher Bracket
Another Bracket
Advanced Projections Bracketology
The Barking Crow
Bub's Bracketology
Calm Yourself Bracketology
Clay Ramsey's Bracketology
Dubz on Hoops
Evan Miyakawa's Bracketology
FOX Sports - Mike DeCourcy
HerkyHopeful's Sports Blog
Jakesnake42 Bracketology
jMorr Bracketology
JNG Nitty Gritty Rankings