The publicly available codes on this thread are working as far as we know. Please note that not every code will work for every property worldwide.

The best thing to do, rather than just posting "I'm staying at (fill in the blank)/does anyone have a code", is to try all the codes first. As such, this thread is not for "cheaper rate" requests.
Note that It's highly unlikely that FTers will find a code that isn't already listed based on a one-off request.

If the code is available at the property, it will show that/rate. If it's isn't available, it will let you know that. Please note that if if one (or more) code is available, only you can determine if the cost savings fits with your budget. If it does, great. If not, you might want to try and see if the property has a local promotion going or if you can use LNF (Look No Further/Best Rate Guarantee) for a better rate. Also note that sometimes a publicly available code may show a higher rate than just a regular booking. Not always, but sometimes.

If you have discovered a new code, please post it in this thread and update this Wikipost. But please, this list is ONLY for publicly usable codes. No corporate or private use only codes please. Thanks!

Online Reservations:

Check here for current US offers (many popular multiple location offers listed below)
Check here for current UK/Europe offers
NOTE: many codes below are re-used for different offers after expiry dates shown - therefore DO NOT delete the 3 digit code as it may be live with a new offer.

53M Earn 2k everyday at Courtyard - Valid stay dates: Dec 20, 2023 - Mar 13, 2024 (link here)
6ME: free breakfast when you pre-pay in full with Visa

AAA also good for CAA members
AAZ Breakfast rate for AAA members (works as of 12/17)
A9M All State Motor Club - Thursday-Sunday (no longer in use, Shodokai corp)
ADP Save up to 10% in Urban Properties - Valid stay dates: Dec 01, 2023 - May 31, 2024 (link here)
ADV advance purchase
A1X Percent-off Amex code for MVCI properties (requires payment by AmEx card)
AMX American Express - No longer in use.
ARN Culture package/Discover Europe
AXC AMEX Centurion, special booking requirements

B18 Up to $100 Bonus Buck promo - Certain US properties
BP6 Business Boost Package - Canadian FS properties
BAR Best Avail Rate
BOG Buy 1 get 1 free - Springhill Suites/Buy 2 get 1 free, buy 3 get 1 free, buy 4 get 2 free in Middle East and Africa
BWG Buy One Get One Free ( now for Geodata Group)

C9E Free breakfast when you pre-pay in full with Visa
C9N Canada Discounts
C8E 20% off Europe Weekends and/or 3 for Germany CYs
COR: General corporate/business rate
CRP Corporate - No longer in use.
CUE Eastern U.S. Cultural / Arts
CFY Can't Beat Friday - UK (requires a Friday night stay)

D3Q "discount" rate for various promos
D18 Deluxe Dining Package
D34 Special promo rates in europe and some u.s. areas
D50 Special Value Rate
D52 Northwest airlines specials in southwest US (no longer in use)
D55 Earn a $25 Visa Gift Card when you stay at participating Marriott properties and pay with your Visa® card.
D56 Family Fun pkg resorts AZ CA FL HI NV TX
D58 Sea World Orlando Promo (RI, SHS and FI by Sea World)
D60 Taste of Italy (dining packages, not only in italy)

EAT Meal Promo
EMV Theme park
ENC Encore Discount
E0P E0G E0S (Zero's folks) - elite promo codes (Example link here)

F8L Family fun in the SE USA
FAL “junk rates” OR
FAL Fall in love with ATL
FPL Florida Power & Light
FML Family rate pkg
FXL Florida Resident Rate
FR6 Florida Resident Rate

GOF Golf Package

H30 Free night stay in southeast
HDK Complimentary room upgrade or discounted suite in the US & Canada. Valid stay dates: December 01, 2023 - January 12, 2024 (link here)
HOL Holiday
HON Honeymoon
HPR Stay 3 get one free

I24 Renaissance Hotels or SE FS Marriotts 3 night min $100 credit

LLR Cops/Firemen - or 2 rm family pkg World Center
LPR Local promotion rate
LRR Leisure Rate
LTS Long term stay - Min stay 5+ nights at hotels, 7+ nights at resorts in US & Canada - Valid stay dates: Dec 01, 2023 - May 31, 2024 (link here)
LVU Love You Special Rates

M96 Asia Pacific Member Rates - Valid stay dates: Dec 01, 2023 - Nov 30, 2024 (link here)
M9W similiar to M11 with free b/f for 2006
M11 Marriott Rewards Member Offers (Numerous offers for Members, offers differ by property). Example link for Orlando Hotels here
M12 Marriott Rewards Elite Offers - Must be a Marriott Rewards member
M3D Buy 2 nights, get 3rd free in Middle East and Africa (T&C's) (no longer in use)
M41 Earn 5K points per stay on a premium or suite room - 2 night min - Valid stay dates: November 30, 2023 - February 19, 2024 (link here)
MAJ Family package
MEB Last Minute Weekend (Thu-Sun) Travel Deals, up to 20% off (formerly SPG Hot Escapes) Link.
MEM Marriott Elite Members - Must be a Marriott elite member to use (no longer used- now is "Mediamath" corporate rate)
MR5: Marriott Elite offer
MRP Marriott Rewards Member Offer
MW1 Point Saver Award availability (requires ordering of appropriate award cert)

N8R $50 Bonus Bucks for up to 2 nights
N9R Fall getaway
NCL Family package
NPR Cluster code - may require an id (use with caution)

OTP Come out and play - No longer in use.

P17 Point Saver Award availability (requires ordering of appropriate award cert)
P42 Pere Marquette New Orleans (and different results throughout Europe) also, Florida Spa Package
P74 Hawaii Escape
PES Escape Packages
PK3 Renaissance Bangkok, complimentary upgrade to Studio Suite for 3+ nights stay, expires 12/24/18
PKF Park and Fly
PKG Package Rates (Can sometimes bring up many types of "package" rates)
PSF Parking 50% off
PRO Promotional Rates (Various promotional packages)

QR1 20% off Weekends, US (Valid a/o 2024)

R6M Renaissance $50 Savings Cert future 2 night stay plus free Airline Companion Ticket
R8H Los Angeles Renaissance $76/night F-Su
RAC Regular Rate for Hotel(seems to be same as REG)
REG Regular Rate for Hotel(seems to be same as RAC)
ROM Romance Package for Couples
RXL Relax

S4B Stay for breakfast at Courtyard Valid stay dates: Dec 21, 2023 - Mar 14, 2024 (link here)
SHO Shopping Package
SPA Spa Package at 3 Delta Hotels - Valid stay dates: Oct 29, 2023 - Oct 20, 2024 (link here)
SPO Sporting Event

TFB Two for Breakfast
THM Theme parks
TRS We Car(e) for you

UKH Metro Denver area discount (see post #871 for details)
UK8 15% off 3 nights. 20% off 4-6 nights or 25% off 7+ nights in Europe, the Middle East & Africa. Valid stay dates: Mar 15, 2023 - Mar 14, 2024 (link here)

V12 Marriott Resorts and JW Marriott Summer Gift Card Promotion
V88 London Area Marriott Hotels - No longer in use.

W8S Western hotels special rates
W9S LA Airport
W14 Wedding
W21 Winter Promotional Rates
WKD Weekend
WW9 Stay 2 nights get a Marriott Cheque worth up to €50/$50

XES - AmEx Card Bonus Buck promotional rate
XMA/XSP Xmas offer but works till March in some properties
XML Marriott BreakAway for leisure weekend travel, must show ID for participating companies
XSP From Delta Skymiles statement (unknown if affiliated with above)
XSP also listed again as stay for breakfast

YB3 $20 Target gift card at CYs - No longer in use.
YB6 UK Barclays Promo - No longer in use.
YX1 $50 daily hotel credit when you book a Brightline train ticket (Florida) Valid stay dates: Nov 10, 2023 - Mar 31, 2024 (link here)

Z2H Hot Rates AAA - currently up to 20% off in Florida from Jun 19, 2023 - Mar 31, 2024 (link here)
Z4M Mesa AZ Courtyard - No longer in use.
ZDY - day rate
ZEA RC Amex rate - may include breakfast and daily resort credit.
ZH4 Family Fun rate
ZJL: Various package promos in US and Canada (link here)
ZJ5 50% off your 2nd room in Europe, Middle East & Africa Valid stay dates: January 04, 2024 - January 02, 2025 (link here)
ZX0 Up to $100 Daily Resort Credit in U.S., Canada, Caribbean and Latin America. Valid stay dates: Dec 01, 2023 - May 31, 2024 (link here)

Phone Reservations Only:

WSAS $10 off and breakfast for 2 special rate
MYZZ 25 or 50 % off at select vacation Club Villas
MWAR 3rd night free in Thailand
MMEO 4th night free at select Marriott Offshore resorts in the Carribean
MWAQ JW Marriott Orlando Grand lakes & Orlando World Center
LLOF JW Orlando Grande Lakes Summer Reconnect Package:
RDPR $50 Dining Credit daily at participating JW Resort hotels