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How to open .C9R files on Android

To open .C9R files on Android, .c9r files are vault internals; on Android, use Cryptomator to access/unlock the vault (the whole vault folder) instead of opening a single .c9r file.

Step-by-step instructions

  1. .c9r files are vault internals; on Android, use Cryptomator to access/unlock the vault (the whole vault folder) instead of opening a single .c9r file.

Alternative methods

  • Open .C9R in a browser-based viewer if desktop apps fail.
  • Try opening .C9R on Android with a secondary app to rule out app-specific issues.
  • Convert .C9R only with trusted tools when direct opening is not possible.

Common issues

Trying to open a .c9r file directly shows gibberish or an error

.c9r is encrypted vault data and is not meant to be opened by text editors, media players, or office apps.

  1. Open the vault (the entire vault folder) in Cryptomator and unlock it to access the decrypted files.
  2. If you don’t know where the vault is, search for the surrounding Cryptomator vault directory rather than focusing on a single .c9r file.

You only received a single .c9r file

A .c9r file is typically just one encrypted object inside a vault. Without the rest of the vault structure and correct credentials, it is usually not usable.

  1. Ask the sender for the complete Cryptomator vault folder (all files/folders that belong to the vault), not just one .c9r file.
  2. Confirm you also have the correct password/key required to unlock the vault in Cryptomator.

Vault unlock fails (wrong password/key or mismatched vault format)

If credentials are incorrect or the vault was created with a different configuration/format, Cryptomator cannot decrypt the contents.

  1. Verify you are using the correct password/key and the correct vault folder (not a copied subset).
  2. If the vault was moved or synced, ensure the entire vault content is present and consistent before trying again.

Security note

Treat .c9r as encrypted content: the main risk is data loss if you lose the vault password/key; keep credentials and recovery information safe.

Back to .C9R extension page