Summary
Host Tools automatically generates a unique access code for each guest's smart lock. You can also set a custom code for any reservation if you prefer.
How automatic codes are generated
If you are fully connected to Airbnb (have availability syncing enabled), Host Tools uses the last four digits of the guest's phone number for their door code. Airbnb has started to phase out the sharing of guest phone numbers and now shares an Airbnb number that routes to the guest's phone. This means that codes may not be associated with the guest's actual phone numbers. It is safest for all guests to not mention their phone number and just use the tag for {{Guest Lock Code}} in your messages to make sure that the code they are given matches what is set on the lock.
From September 28, 2026, Booking.com no longer shares guests' phone numbers with connected software. For Booking.com reservations without a phone number, Host Tools generates a unique code as soon as the reservation arrives. That same code is added to your lock and appears in your messages wherever you use the {{Guest Lock Code}} tag, so the code your guest receives always matches the code on the lock.
All generated codes are validated against your lock's specific constraints. For example, TTLock devices may not support certain digits, and Nuki locks cannot use codes that contain zeros or start with 12. Host Tools automatically adjusts the code to comply with these restrictions so guests always receive a working code.
Setting a custom access code
You can override the auto-generated code with a custom access code for any reservation:
Open the reservation in your Inbox
Click Reservation Details
Enter your preferred code in the Access Code field
Click Save
Host Tools will validate your custom code against your lock's constraints before saving. If the code doesn't meet the lock's requirements, you'll see an error message explaining which constraints were not met.
Using the lock code in a message
To include the guest's lock code in a message rule, use the {{Guest Lock Code}} tag. Here is an example:
KEY: There is a keypad attached to the front door. Your access code is {{Guest Lock Code}}, followed by the checkmark on the keypad. Please note that this code is not active until your scheduled check-in time. To lock the door when you leave just press any number.
⚠️ Important: You should not mention that the code is connected to the guest's phone number in your message, since the code may not come from their phone number.