We’re increasing the length of Trello tokens. Existing tokens will continue to work, and new tokens will be 12 characters longer.
These changes are planned to be rolled out fully by November 16, 2022.
The tokens are longer because we’re creating a new standard prefix/regex shape for Trello tokens and secrets. This will allow us to automated detection and discovery for leaked tokens.
However, please note that tokens are meant to be “opaque”, meaning their length, shape, or format is not guaranteed. Your application code should not assume anything about the token’s structure. If your application relies on Trello tokens having a specific structure, such as matching a certain regular expression or having a certain character length, you should remove that logic immediately.
But if your app code is already treating Trello tokens as opaque, then you are all set! No action required.
You can see the official changelog entry here (it has the same information as this post).