The Altamira app uses the following permissions:

• camera – to allow scanning a QR code containing the full address of another Mastodon account in order to easily follow that account
• (coarse) location – to display and/or automatically follow hashtags identifying a coarse user location; in order to optionally do this in the background, the app also declares to use permissions for fine and background location. These permissions are not requested in the app, but only used if the user manually enables them via their device’s settings.

In order to perform core functionality of the app, it is necessary to sign in to an existing Mastodon account. If the user chooses to do so, the app might store any of these types of data on the device:

• necessary OAuth data as defined in the Mastodon API documentation
• Mastodon ID values for the user’s account, as well as for lists and filters used by the app
• if the user opted in, hashtags encountered in statuses of the user’s home timeline, including metadata such as number of occurrences, first and last occurrence and actions the user has performed on each hashtag
• if the user opted in, coarse location data (on the order of ~ 5km x 5km) of previously visited locations

Additionally, the app might have temporary access to the following data, meaning that this data is not permanently stored on the device:

• if the user opted in, full text and metadata of statuses appearing in the user’s timeline
• if the user opted in, IDs and other metadata of accounts followed by the user’s account
• if the user explicitly forwards/shares this to the app, URL and content of statuses the user wants to boost

The app can send the following information back to the user’s Mastodon instance, if the user opted in or explicitly initiated the action:

• follow/unfollow hashtags, including those based on a previously visited location
• add/remove filter strings to/from a filter
• add followed accounts to a list, or unfollow them
• send status updates
• boost statuses

Information stored on the device can be deleted by visiting app settings in the Settings app on the device.