Jottacloud alternative File System (JaFS) is a C# library for administration of your filesystem at Jottacloud.
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Jottacloud alternative File System (JaFS) is a C# library that wraps the HTTP REST API available for the cloud storage service Jottacloud by the Norwegian company Jotta AS.

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Jotta AS is a Norwegian company that operates under Norwegian jurisdiction, safe from USA PATRIOT Act and with a privacy guarantee. This, together with their ulimited storage option, make them have an appealing offer in the crowded market of cloud service providers.


This is not an official product from Jotta:

The REST API, called JFS (Jottacloud File System), is available at (and It is not officially announced or supported, and no official documentation exist, but the company founder has mentioned it and given some short instructions on how to use it for read operations in the official forum. Write support was not mentioned, but in a now deleted forum thread, company staff endorsed attempts to use that too: We won't ban anyone for tinkering with this, we actually like that our users are showing this much interest in our service. As long as you don't break any laws or disrupt the service, we would encourage you to keep testing stuff out.

This library has been implemented based on the short instructions in the forum, by observing (reverse engineering) what the official client does, looking into other open source projects which has done related things (such as JottaLib and node-jfs, and general trial and error.

Use at your own risk:

Use of this library, any parts of the source code, or any of my descriptions are entirely at your own risk. I take no responsibility for any trouble you get yourself into, such as if you loose all your data or get kicked out from Jottacloud. But of course, I am doing my best to make sure that nothing bad happens.

As described above, this library is developed by reverse engineering and not based on official documentation, and this may be a source of error. This also means that the functionality can stop working without any notice, should Jottacloud decide to change the API.

Please add anything you find to the bug tracker.

White label products:

The REST API is shared with the various whitelabel products like Get Sky, Elkjøp Cloud etc so this library should also work for them. Please let me know if you have tried on any such products, so I can gather a list of what works and what doesn't (just add a issue or something).


Source code is in C#, with Visual Studio 2017 project targeting .NET framework version 4.6.1, building as "Any CPU". Add as project reference, or build it and add assembly reference, to your own project.


Using the main C# library from PowerShell

One neat tip is to load the main C# library (JottacloudFileSystem.dll) into a Windows PowerShell session by Add-Type -Path <PathToLibrary>, and then you can use the functonality from an interactive shell. If you are on PowerShell 5.0 or newer you can execute using namespace JaFS

Example for PowerShell 5:

Add-Type -Path .\JottacloudFileSystem.dll
using namespace JaFS
$jafs = New-Object Jottacloud((Get-Credential).GetNetworkCredential())
$jafs.AutoFetchCompleteData = $true
$mnt = $jafs.GetBuiltInDevice().GetMountPoint("Archive")

Using the PowerShell Provider

Work has started on wrapping the main C# library (JottacloudFileSystem.dll) in a PowerShell provider library (JottacloudPSProvider.dll), so that you can use the familiar commands such as Get-Item, New-Item and Remove-Item to manipulate devices, mount points and folders in Jottacloud:

[Reflection.Assembly]::LoadFrom("JottacloudPSProvider.dll") | Import-Module
New-PSDrive -Name JAFS -PSProvider JottacloudPSProvider -Root \ -Credential (Get-Credential)
Test-Path JAFS:\PC001
Get-Item JAFS:\PC001\Backup
Get-ChildItem JAFS:\PC001\Backup
New-item "JAFS:" -ItemType device -Value PSProviderTestDev -DeviceType LAPTOP
New-item "JAFS:\PSProviderTestDev" -ItemType mountpoint -Value PSProviderTestMount
New-item "JAFS:\PSProviderTestDev\PSProviderTestMount" -ItemType folder -Value PSProviderTestFolder
Remove-item JAFS:\PSProviderTestDev\PSProviderTestMount\PSProviderTestFolder
Remove-item JAFS:\PSProviderTestDev\PSProviderTestMount
Remove-item JAFS:\PSProviderTestDev -Permanent

Note that this is on an even earlier stage than the main C# library!


Use in combination with the official web user interface is recommended, both to verify changes but also to handle things not supported by this library yet.

The navigation in the file system structure (JFS) offered by the REST API is by use of URLs[username]/[device]/[mountpoint]/[folder]/[subfolder]/[file]. In the JaFS library you log on as a specific user, and all paths in the JaFS methods are relative to this: /[device]/[mountpoint]/[folder]/[subfolder]/[file].

The main object in the library is the file system object. From there you can get devices, then from those you get to mount points, then folders and files. You can also find items by path, and generate file tree lists from the file system object.

File system objects you get from the library, such as device, mountpoint, folder and file objects, contain some minimum of information about child objects. For each child object an additional request needs to be sent to the REST API to get all details, for instance children of that again. To reduce the traffic this is by default not done automatically, and you must call the method FetchCompleteData on the objects to do it. There is a property AutoFetchCompleteData on the main Jottacloud file system object which you can enable to make this happen automatically: The detailed information are then retrieved when you call a method which needs it, but not before.



At the top level in the JaFS structure is what is called devices. There is always a built-in device with name Jotta, reserved for the built-in functionality offered through the official web user interface and the official desktop client, like the file synchronization, archive, file sharing etc. If your account supports it, additional devices can be created from the official client software using its backup feature. Any devices other than the built-in device will show up in the backup section in the official web interface. Whether you can have multiple devies depends on your account type. Unlimited accounts can have an unlimited number of devices.

JaFS support creation of new devices and deleting devices. Note that deleting a device is always permanent, it will not be moved to trash with the possibility for restoring it later. Renaming of devices are not supported yet.

Mount points

Devices contain mount points. Mount points are more or less just a kind of root folder. The built-in device Jotta contains some built-in mount points which are used from the official software:

  • Archive are a generic file store accessible through in the web user interface only.
  • Sync is where the files synchronization with the official desktop client are kept.
  • Trash is a temporary storage for files that have been marked as deleted, but not permanently erased yet. Jottacloud saves deleted files for a minimum 30 days before permanently deleting them. Files and folders from the any of the other mount points will be present here, and also deleted custom mount points.
  • Links is a special mount point for sharing of files by giving public access using a secret. This mount point is not behaving like folder and is therefore excluded by default from the JaFS methods that are working with mount points (but can be included with an extra argument).
  • Shared is an old mechanism for the sharing logic now in Links, i think.
  • Latest is also a special mount point, this is for showing recent activity. Also not behaving like a folder and excluded by default from the JaFS methods that are working with mount points.

When you in JaFS retrieves mount points on the built-in device you will get Archive and Sync back. The special mount points Trash, Links and Latest are not by default exposed as mount points, the corresponding functionality are handled via dedicated methods instead.

The backup functionality in the official desktop client creates a device specific for your client, and then on that device one mount point for each backup set (folder) that you configure.

JaFS allow you to create new mount points, but by default only for custom devices. These will show up in the backup section of the official web user interface. With a special option you are also allowed to create new mount points also for the built-in device, but these will not be shown in the official web user interface so you must be a bit careful with this.

Custom mount points can be deleted, and will then be moved to trash (will look like a folder in the web user interface). You can also delete them permanently. Rename/move is not supported yet.

As mentioned above; mount points are more or less just folders (except the special ones), and they contain lists of folders (sub-folders) and files (files can be stored directly on mount points and does not have to be in files). Mount points have a size property counting the total storage used by the mount point, this information is not on regular folders.


Folders contain lists of folders (sub-folders) and files. Not very surprising. You can create new folders, rename/move them, delete them into trash or delete them permanently. There is also a method for uploading a local folder, which will loop trough it and create folders and upload files to the server location. There is also a corresponding method for downloading a remote folder.


Files are stored in folders (or directly on mount points). You create files by uploading a local file into a specified path. You can also rename/move files, delete them into trash or delete them permanently.

Two important concepts of files in JFS is state and revisions. Jottacloud keeps track of the latest successful/completed upload of a file and stores it in a revision named "current revision". Whenever there is a unsuccessful upload, e.g. due to hash or size mismatch, it will store it in a revision name "latest revision". Any older revisions are stored as "revision". The file revisions have a state property telling if it was "Completed", "Incomplete", "Corrupt" (hash mismatch), etc. In JaFS the file types are organized as a hierarchy: All files are JFSBasicFile, and then there is derived types for corrupt files (JFSCorruptFile), incomplete files (JFSIncompleteFile) and complete files (JFSFile), adding more and more features. For example only JFSFile has a Read method (you can only download content of complete files, and only JFSIncompleteFile has a resume method (to continue upload where a previous incomplete upload ended). But all files have Write method so that you can upload new content for it. Note that when you retrieve file objects from containers (such as folders or mount points) you will get them as JFSBasicFile, and you will need to cast it according to the type. The JFSBasicFile class has properties for checking which type it really is.

Timestamps for when the file was first created and the time of the last update (write) are preserved, but not timestamp for last read (access). Timestamps of folders are not preserved, as Jottacloud does not store them (only for mount points).

Jottacloud includes functionality for sharing files, by generating a unique "secret" for it that can be used in a special URL for anyone knowing the secret to have access to the file.


In general the main forcus so far has been on handling the data structure, with devices, mount points and folders. File handling with uploading/downloading of files is also implemented, but there are some issues.

Some of the things that have issues/are not completed/not started on yet:

  • The uploading of folder with the "SkipIdenticalFiles" option, which is intended so save traffic by checking MD5 of already uploaded files, seems to have issues (the cphash argument in the API request).
  • Robust handling of any kind of issues that can occur during file upload.
  • Proper handling of file versions.
  • Restore deleted items from trash (haven't found any API query that works).
  • Rename mount points (haven't found any API query that works).
  • Rename of devices (haven't found any API query that works).
  • Sync-operation, e.g. delete files from remote folder which are no longer present in matching local folder. Not sure if this will ever be part of this library though, probably better to build something on top of it for these kind of features. Maybe implementing Jottacloud support in rclone is a better option?

Side notes

Check out Duplicati, a free, open source, backup client that securely stores encrypted, incremental, compressed backups on cloud storage services and remote file servers. I used my experience from the current project to contribute with a Jottacloud backend, so that you can store unlimited amount of encrypted, incremental and compressed backup.

I also recommend Syncthing, an open source, cross-platform, encrypted, continuous file synchronization program for synchronizing files directly between devices.


Help needed first of all with testing, and reporing any issues found.

Then if you can figure out some of the missing pieces in the Jottacloud API (see the limitations section) it is also highly appreciated.


Version 0.1.1

Added PowerShell Provider library.

Version 0.1

The initial version published on GitHub. The main structure is place, management of devices, mount points and folders should work with the limitations mentioned in text above. Main concern now is to finish the file upload handling.


I got much help in understanding the REST API by looking at the Python utility JottaLib from @havardgulldahl, and also the Node.js utility node-jfs by @paaland was helpful.


All code is licensed under GNU Lesser General Public License version 3 (LGPLv3).