What you need to know about B2 Bucket names What you need to know about B2 Bucket names

What you need to know about B2 Bucket names

Andy Andy

The first thing you will most likely do when using B2 is create a "Bucket" in which to store your files.  Here's what you need to know about Bucket naming rules followed by a short FAQ. 

Bucket Naming Rules 

  • Bucket names are globally unique.  This means if another B2 user has created a Bucket named for example "myphotos", then you cannot create a Bucket named "myphotos".
  • Each Backblaze B2 account can have a maximum of 100 Buckets.
  • Bucket names must be a minimum of 6 characters long and a maximum of 63 characters long.
  • Bucket names can be consist of numbers (0-9), letters (a-z) and the "-" (dash).  No other characters are valid, including "_" (underscore).
  • Bucket name are case insensitive, meaning that "MYPhotos" is the same as "myphotos".
  • Bucket names that start with "b2-" are reserved by Backblaze and cannot be used.


Q:  Why are Bucket names globally unique versus "Account" unique?
A:  If Buckets names were only Account unique, then the Account name is required to make the URL or API call to the bucket unique.  This means the Account name could be publicly visible, depending on how the URL/API is used.   To protect B2 users from the inadvertent release of their Account name, we use the unique Bucket name instead.  We are considering strategies to change this capability while protecting Account information.

Q:  Why can't I use "_" in Bucket names?
A:  The underscore character is not valid in DNS tables.  Allowing the underscore would limit the ability to cache files and also would limit our ability to create vanity URLs (a proposed future capability).

Q:  What about creating Bucket names using multi-byte characters?
A:  Currently multi-byte characters are not supported.  Only a-z, 0-9 and "-" are valid.

Q:  Can I rename a Bucket?
A:  No.  Currently, renaming a Bucket is not supported.

Q:  Do the limitations on Bucket names apply to file or folder names.
A:  No.  In general, file names can consist of any UTF-8 string up to 1,000 bytes long, but there are a few picky rules.

    • No character codes below 32 are allowed.
    • Backslashes are not allowed.
    • DEL characters (127) are not allowed.
    • File names cannot start with "/", end with "/", or contain "//".

        For a complete discussion of file names, file ids, and more, please visit https://www.backblaze.com/b2/docs/files.html.