Frequently Asked Questions

Got a question about ownCloud?

Explain to me in simple terms what ownCloud is and why I would want to use it, please?

Running ownCloud

I have Questions about the ownCloud Marketplace.


ownCloud Community


ownCloud for professional use

See also the ownCloud Enterprise FAQ.

What is this ownCloud thing? Why would I care?

ownCloud is a file sharing server that puts the control and security of your own data back into your hands.

Today, most people have their digital life stored on online servers from various companies. Think Google, Apple, Facebook, Twitter, Dropbox, Instagram and many others. You uploaded your pictures, your music, your daily ramblings, happy and sad thoughts. You use these services to share with others, to send and receive emails, store address books, play music and video, have your files available on any device you want. All great features, no doubt! When your phone breaks, just having to log in to the new one to find all your pictures, contacts and other settings is an amazing and reassuring capability brought by these services, often (perhaps incorrectly) called ‘the cloud’.

But you might wonder: “Where is this data? Who has access to it?

These questions have become more pressing since the revelations that our own government is spying on us, and collecting and snooping into virtually all of our online communications.. We know that foreign and our own governments have access. Criminals and large corporations, too. This knowledge about us can be used and abused in many ways, for financial gain, for control, for harmless and harmful fun.

Many people prefer to have more control over who gets to see the photos they send to their spouse or friends, who gets to read their bank account statements or determine their political allegiance. Or know where they are – as mobile phones track your location pretty much continuously…

This is where ownCloud and similar technologies come in. ownCloud offers you the option to take back your data. Once you install it on a server (or let somebody do that for you! Decentralization is an important tool to protect privacy) you can access your private data in an easy to use web interface or synchronize it with your devices like Android and iPhones. You can store your contacts and calendar as well as files on ownCloud and, through the many ownCloud apps, use it to store passwords, play music and movies and so on. It also allows you to securely share with other people and collaborate on documents. Learn more about ownCloud features here.

All this is free, as ownCloud is available under an ‘open source license‘, which gives you the right to examine, share and modify it. ownCloud is developed by an international community of both paid and volunteer contributors and you can get involved, too.

Things ownCloud does not do

Note that ownCloud is NOT a backup tool: the desktop client, for example, will synchronize the contents of a local folder with the server. That works for file modifications and additions, but also deletions. If you delete a file on the server, it gets deleted on all devices that you installed the client on! And if you delete a file on the client, it gets deleted on the server and then deleted on other clients that were syncing that file. ownCloud does have a trash for deleted files and retains older versions of files, which means deleted or modified files can be brought back. But this functionality can be disabled by the system administrator and depending on the space usage settings, deleted or older versions of files get deleted over time. You should always backup your ownCloud server!

Similarly, note that External Storage and the Server to Server sharing which ownCloud supports, connects ownCloud to an external storage like FTP or Samba, or to another ownCloud server. Files will show up in your web interface and can be synced with the client. However, they are not replicated on your ownCloud server! They are merely fetched whenever you request them in the web interface. Once the external storage disappears or the other ownCloud server retracts your access, you can no longer access the files! Make a copy if you want to have them on your own ownCloud server.

See what ownCloud can do in this video

ownCloud - Whats new in ownCloud

Running ownCloud

Where do I find information on how to use/install ownCloud?

I have a problem, what do I do?

  • If the ownCloud Documentation does not help and Google can’t solve your problem either you should check out our support page.
  • At the ownCloud community is helping each other with problems. You should ask for help there! Or better, do a short search in the central if someone else had the same problem before and already asked.
  • If you are using ownCloud in a business, educational setting or other professional or large scale deployments, note that the ownCloud GmbH offers support contracts as well as resources like white papers, webinars and a knowledge base to help successfully deploy and use ownCloud in your business.

Where can I discuss ideas with other ownCloud users?

The best places for conversation are:

If you have a feature request or proposal which you can support with code, check out our contribute page. You can put feature requests in the issue tracker but please be aware that in open source projects like ownCloud, the constraint is rarely ideas or awareness of what can be improved but rather time to work on them. Contributing is the best way of making change happen!

Note that Bountysource offers a way of backing feature requests with your wallet.

If you want to connect with other ownCloud users and enthusiasts, check out our social media channels.

I want to upgrade my ownCloud installation to the new release, how do I do that?

  • The manual upgrade process is described in the ownCloud Documentation.
  • If you installed ownCloud using Linux distribution packages and added the repository, an update will get them. You can also manually grab the new versions from
  • The built in Update app will usually have new ownCloud releases available for upgrade some time in the week after a major release.

Is it safe to upgrade to the new release?

All code entering ownCloud has been reviewed twice as well as tested by both automated means and through the efforts of volunteers. Releases are done only when all issues we are aware of are fixed or can be mitigated easily. In short, ownCloud releases are always as stable as we could make it without your help. If you want the guarantee that it will work in your specific situation, make sure you help test before a release is made so your issue can be fixed in time.

Why do we need your testing?

In short: because ownCloud is yours. ownCloud is an Open Source product, following an open development model. That means that many different stakeholders, both commercial and private, contribute to its development and share responsibility for the final release. ownCloud is thus neither owned nor controlled by any single entity.

By using ownCloud, you become part of the ownCloud community, sharing both ownership and responsibility for the product we collectively develop. Compare it to your responsibility for the functioning of your car: you regularly have to test it, or hire a garage for a checkup. It is yours, isn’t it?

If I have my ownCloud server hosted, does that still help me protect my privacy?

  • Yes, it does. Decentralization helps protect your data by making it harder for an attacker to find, and less valuable if they do (decreasing motivation). Moreover, you get to choose where and with whom you host your data – so you can find a jurisdiction which protects you better, or host your data at a local company you trust. See this blog post for more details on this.


Why does ownCloud use csync rather than rsync?

  • rsync is a one-way syncing protocol. This means that if you have two servers and delete a file on one side, it will pop up again if you use rsync. To ensure old files get removed but new files added, and updated files overwritten, you need a N-to-N sync solution. ownCloud uses csync for syncing, which also deals with conflicts in a smart way.

Why is ownCloud Server written in PHP?

ownCloud is for everybody. We picked PHP because:

  • PHP runs anywhere and is supported everywhere. Even the cheapest hosting provider should support ownCloud and PHP makes that possible.
  • PHP is easy to learn which makes it easy for people to contribute. The ease of PHP also allows you to check the code that runs your ownCloud and make changes that you need.

In short, PHP lowers the barrier for using, auditing, modifying and contributing to ownCloud. And that is important!
See more details in this blog about ownCloud and PHP.

Why do you use HTTP and not another protocol?

  • HTTP goes through every firewall and proxy.

Why does the calendar/contacts app not work with Android?

  • iOS has native ical/caldav support, Android does not. You have to use an Android app that does but unfortunately almost all apps we’re aware of that support caldav/ical are paid. One open source client is DAVdroid. You can find a list of 3rd-party apps which work with ownCloud here.

Why does the Android/iOS mobile app not support my favorite feature?

  • The Android mobile app has automatic picture and video upload. Both mobile clients give access to your files and include selective sync for keeping some of your files up to date on the device. Other features are under development or provided by other apps (like calendar and contacts, see previous FAQ item). If you’d like to add features to the Android or iOS client, find the Android sources here and the iOS sources here. Legal notes: the Android app is under the GPLv2, the iOS app under the GPLv3. To contribute to either, you have to sign a contributor agreement or contribute your code under the MIT license. For testing, we provide a iOS license exception so you can run the iOS app on up to 100 devices.

Why are Calendar and Contacts (or another app) not shipped with the zip file, are they not part of ownCloud?

We have four types of apps: Core, Official, Approved and Experimental. To keep the official zip file of a reasonable size, we only ship the core functionality. Other apps are, however, just one click away!

This is what the four categories mean:

  • Core means part of ownCloud core, like sharing, gallery, external storage, encryption. These are integral parts of the ownCloud experience and problems in these apps will block releases. ownCloud GmbH offers support on these to customers and while not all core functionality is maintained by employees, ownCloud GmbH. takes responsibility for stability and of the entirety of ownCloud core.
  • Official are apps which are quite well maintained and important for ownCloud users. They include Calendar and Contacts. Being ‘official’, we deeply care about them and will try to have them available for new releases on release day, but they are still developed by volunteers. This also means there is no commercial support available from ownCloud GmbH. This often also means that it is not guaranteed that these apps work well on systems with large numbers of users or large amounts of data.
  • Approved means that an app won’t immediately eat your data, that we have made sure there are no security problems and the maintainers have worked with us to ensure that. No promises beyond these points!
  • Experimental covers the rest. These apps are neither checked for stability nor security problems and you should be careful when installing them – they might compromise your privacy, security or data integrity.

Changes of status can happen following the rules documented here. In simple words, the better maintained an app is, the more fitting an ‘official‘ label is. If a company, be it ownCloud GmbH due to customer demand, or another company, decides to dedicate resources to maintaining an app, it could become part of core. Your help thus matters!

How Secure is ownCloud?

  • ownCloud supports HTTPS and offers server-side encryption. ownCloud Server automatically generates a 4096-bit strong private/public key-pair for each user. Private keys are encrypted with the user’s login password and thus nobody can get at your data if you are not logged in on your ownCloud server.
  • ownCloud is an open source project so all code is visible. We are committed to building secure code and work following the leading industry security practices. We employ a full-time security expert and do regular security audits on the code. Our bug bounty program on hackerone provides an opportunity for white hat hackers to get rewarded for responsible disclosure of ownCloud vulnerabilities. We always welcome notifications of security issues, see
  • To learn a bit more about ownCloud security, watch this technical talk at the ownCloud Contributor Conference and read this article about ownCloud and encryption.

Does the long list of security advisories mean ownCloud is less secure than other solutions?

Rather the opposite. It signals that ownCloud is a mature project taking responsibility for its security.

  • ownCloud is being used by many large corporations in security sensitive situations (including banks and defense agencies), see ownCloud GmbH customers and has undergone independent security audits. As an open source project, it benefits from a large numbers of eyes looking at its code.
  • We are highly committed to full, yet responsible disclosure of security issues, which is why we publish all potential security relevant issues with a CVE. A CVE is an international standard in security and availability of ownCloud CVE’s means system administrators can easily see whether their infrastructure is vulnerable or not.
  • No other open source file sync and share receives the scrutiny and security attention ownCloud has. While a lower or higher number of CVE’s does not directly say anything about security by itself, issuing CVE’s is part of widely accepted responsible vendor security practice.

Are files encrypted during sync?

  • Yes, we use TLS for sending and receiving files over the network so they are encrypted during transmission.

Does ownCloud support file encryption on the server?

  • Yes, but the Encryption app is designed to protect your data on external storage, rather than on the server ownCloud runs on. In the current design, the server always has the keys to the data. They are encrypted by your password, but you can’t trust that it is as secure as client-side encryption. ownCloud does not do client-side encryption because you can not have a web interface if the server can’t read the files and the web interface (and sharing abilities!) are very central to ownCloud. So you will always need to be able to trust the server if you want to ‘own’ your data. Read more in this article.
  • If you really want client-side encryption, we recommend you look for other solutions. Of course, if you are sufficiently knowledgeable and skilled, you would be more than welcome to improve on the file encryption technology. If you are interested in supporting or working on this feature, check out github for the latest state on the discussion about it and check out to get started.

Can I use ownCloud as a backup solution?

No, ownCloud is absolutely not a backup solution:

  • Changes you make in one place are synchronized to other places which means that if you accidentally remove or overwrite a file on your local system, ownCloud will remove it from the server.
  • If a file get’s corrupted at one place the corrupted file get distributed to other places.
  • The ‘previous files’ and ‘undelete’ functionality of ownCloud is merely meant as a convenience and should never be relied upon as a backup function. Algorithms are in place which clean up ‘old files’ and thus, changes will get lost over time.

You should use a backup application to store the files in ownCloud somewhere. The ownCloud documentation has tips on how to back up ownCloud.

Why do I sometimes get conflict files and messages while syncing?

  • A conflict may be caused by two or more users editing the same files at the same time or while on the road before the files are synced. We do not merge changes to files like version control systems like git do; we don’t modify user files, ever. So you will get two files, the one that was synced to the server first and the one you had locally modified in the same time. You can compare the file changes by hand and delete the local file once you’re sure you did not lose data.

Does ownCloud use delta-sync (only syncing file changes)?

  • We introduced chunked, parallel up- and download with ownCloud 7 and the ownCloud 1.6 client. Syncing only file changes needs much deeper changes. It is on our roadmap, but won’t be done soon. Find some background on that decision here. If you want to speed up the development of this feature by working on it, see the github discussion. If you really want this feature and would like to specifically fund work on it, see the Bountysource page.

Does ownCloud do file de-duplication?

  • No, we think that that is the job of the file system. We do maintain versions of files as they are replaced and you may revert to older versions at any time.

Why is ownCloud syncing not faster?

  • The design of ownCloud is constrained by two important features: scalability and reliability.
    • ownCloud is designed to be very scalable, and be independent of the used storage system. We want it to work with petabytes of data and tens of thousands of users – and it does, organizations like CERN in Switzerland and big universities and University Networks run ownCloud with such amounts of data and users.
    • A second design goal of ownCloud is reliability. We would rather be slower, but ensure no files are lost, than risk going fast-and-loose with user data. For example, the file-change-notifications on Linux and Windows are not 100% reliable in all cases, so just-to-be-sure we run a full file system scan periodically. Yes, that eats battery life, but it does ensure you do not lose any of your files!

    This does not mean there is no room for improvement, we work very hard to make ownCloud faster and every release introduces many performance improvements. Also, help is always welcome. Check out the client code on github if you are interested in the challenges of fast, scalable and reliable file syncing! See the contribute pages for more information about getting involved.

Does ownCloud scale to large deployments?

  • ownCloud can run on Raspberry Pi like development boards but is certainly not limited to low-end hardware. Worlds’ largest on-premise cloud deployment services 500,000 students on ownCloud and terabytes of data are shared through ownCloud at organizations like the atom smashers at CERN. ownCloud co-founder Frank Karlitschek wrote a post about the scalability of ownCloud.
  • Of course, it does require some tuning to adopt ownCloud for large deployments. For best performance the architecture needs to incorporate some best practices. See our documentation on performance tuning and the pages on scaling across multiple machines. See also for some best practices and experiences from ownCloud GmbH customers. You can find excellent resources in other places online, like this blog about a High Availability cluster with Galera for MySQL and glusterFS, another one from the same writers, this glusterFS and ownCloud blog and this post about making LDAP fast.
  • When multiple installations are an option due to geographical or task related separation, using the Federated Cloud Sharing functionality to run separate ownCloud instances which link to each other can be helpful when scaling to hundreds of thousands of users.
  • In general, scalability of ownCloud goes up significantly in each release. For example, ownCloud 8.1 can sustain over 50% more users on the same hardware as ownCloud 8.0 could. If the ability to have many users on a single ownCloud server is an important consideration, use the latest ownCloud Server and client versions.
  • Check out the core code on github if you are interested in the challenges of fast, scalable and reliable file syncing! See the contribute pages for more information about getting involved.

Is ownCloud Server limited to a certain number of users or files and do I have to purchase something to get a ‘full’ version?

ownCloud is open source, so artificial limitations have no place in it. It can sustain the same number of users, downloads or data as a version equipped with enterprise apps and a support contract.

ownCloud Community

Where is the ownCloud community hosted?

How big is the ownCloud Community?

  • ownCloud has an estimated 8 million users and over 350 programmers contributed code in the last 12 months. Tens of thousands participate on our forums, mailing lists, translation and documentation tools, and IRC channels in testing, discussions, translation, documentation and so on. See this blog for an analysis and dig into the statistics on Bitergia so you can judge the health of our community yourself. We track the development of the ownCloud user and contributor base on our history page.

How can I get involved in the ownCloud Community?

But what if I’m not very technical?

  • There are lots of ways you can contribute to ownCloud. We have a need for developers, designers, event organizers, speakers, QA and more. It is all on the contribute page!

How can I get started writing mobile (Android, iOS) clients or third party (web) apps?

  • First of all, awesome you want to bring ownCloud support to your app or build an app entirely for ownCloud, rocking!
  • If you’re interested in writing an Android or iOS app with ownCloud support, you can use our MIT licensed libraries on those platforms. Find them on Github: iOS, Android. You can then use the iOS and Android developer docs.
  • To build a third party application accessing ownCloud data through its external API, find the documentation here.

Where can I find ownCloud apps?

  • There is a large selection of built in and community-approved apps available for download from within the App management screen in your ownCloud installation. Featuring apps like the Music app, the Calendar app and so on you can watch your movies, share your pictures and keep your bookmarks synced. Download is seamless (just ‘enable’ the app and wait while it is downloaded, installed and enabled) and upgrading is easy from the same screen.
  • If you want details on the apps, you can also look at our community and enterprise-developed ownCloud apps at that have been developed with our open API. You can find apps in all categories: multimedia, PIM, productivity, games, tools and more.
  • If you are looking for third-party apps that integrate ownCloud in mobile and desktop applications, see our 3rd-party apps page.
  • Building a new ownCloud app is easy. If you’re interested in developing your own ownCloud app, see the contribute page, where you can find a link to the latest App Development documentation.
  • If you have questions about the ownCloud Marketplace, you should take a look at its FAQ.

Where can I find ownCloud t-shirts, stickers and other swag?

  • ownCloud has a store on this page where you can find posters, mugs, stickers, magnets, buttons, t-shirts and much more.
  • If you are looking for materials for an ownCloud event or to use to promote ownCloud at a conference or trade show, see our events pages for information on what is available.


DISCLAIMER: The answers below are general directions, not legal advice and we can not provide such. Contact a lawyer if you are unsure about any of this.

Can I modify ownCloud and run it on my website for others to use/access?

ownCloud Server is available under the AGPLv3. In laymen terms (this is NOT legal advice!) the AGPL license grants you the right to run the ownCloud code wherever and however you want, make modifications and additions and share these with anybody you like. The only limitation is that if you give others access to your ownCloud (by giving them a user account or sharing files with them), you must also give them access to the source code; and the whole source (including your modifications) has to be under the AGPLv3 license.

How to comply

If you have made no modifications to the ownCloud code, the easiest way to comply with the AGPL is to have a small link to and note that users can find the code there.

Otherwise, if you have made modifications, contributing these to ownCloud is sufficient from our point of view. If you don’t want or can’t do that, you have to provide a way for users to download the modifications you made to ownCloud, including the modifications. Providing, upon request, a tarball, zip file or github repository is enough. Make sure they contain the copyright notice; the code has to be under the AGPLv3 or a compatible license like the MIT license.

Some examples:

  • ownCloud apps (ownCloud apps like the calendar or music app from, as you would write following the App Developer documentation, using the public but internal API) are considered an integral part of ownCloud; writing an ownCloud app is thus considered modifying ownCloud and your ownCloud apps are subject to the requirements of the AGPLv3. The ownCloud Enterprise Edition provides an exception as it is available under a proprietary license.
  • External apps like mobile or desktop clients, or apps running on another server and otherwise not part of ownCloud but using the external ownCloud OCS API as you would find here are NOT subject to the AGPLv3 and can be under any license you like.
  • Artwork is not subject to the AGPLv3: you can have a branded ownCloud installation, with modified logo, colors etcetera. You do NOT have to release your logo or other artwork under the AGPLv3.
  • If you use ownCloud yourself (as private user or company!) and do not give third parties access to its user interface or API’s (like webDAV), the AGPLv3 sharing clause does not come into effect. In general, note that you are only ever obliged to share the original source upon request with a third party who has been given access to your ownCloud instance. You must merely make sure that users are aware of this right.

Can I write closed source or proprietary apps for ownCloud Server?

  • Yes, but following the requirements of the under the AGPLv3, these can be distributed or made available to users outside of your household or organization only under the ownCloud Enterprise Edition, which supports integration with proprietary technologies. Contact ownCloud GmbH for details.
  • External apps like mobile or desktop clients (like those using the iOS or Android ownCloud libraries, which are MIT licensed) or apps running on another server and otherwise not part of ownCloud but using the external ownCloud OCS API as you would find here are NOT subject to the AGPLv3 and can be under any license you like.

I want to report a copyright infringement or other legal matter on a site that mentions use of ownCloud.

  • ownCloud is an open-source project that can be easily hosted by any person allowing anybody to securely exchange files. Neither the ownCloud open source project nor ownCloud GmbH exert any legal or technical control over those domains. If you found a copyright infringement on a domain other than or, please try to contact the domain owner. ownCloud has no insight or control over ownCloud instances.

Can I use the ownCloud logo on my website, for my ownCloud app or client, or promotional materials?

  • The use of the ownCloud trademark is governed by our trademark policy. In short, we want to support you in promoting, using and building on ownCloud but we also want to prevent confusion about the meaning of our logo and trademark and your use of it. Carefully read our trademark policy before you use ownCloud marks (like our logo or our name) on a website, app, flyer or anywhere else.

ownCloud for professional use

Can I use ownCloud in professional, large scale deployments?

  • Absolutely. ownCloud Server is built for and used by both private and large scale, professional deployments in enterprises, education, research institutions and government agencies. Find some of the bigger deployments among the customer stories.
  • You can use ownCloud for free in any situation – due to the open source license. However, if you require support and certain enterprise functionality, consider purchasing a subscription.

What resources exist to support my deployment?

What is the Standard Subscription and Enterprise Subscription?

  • Professional deployments of ownCloud Server only interested in enterprise file sync and share can benefit from the enterprise service and support offered by ownCloud GmbH through the Standard Subscription.
  • The Enterprise Subscription builds on the support offered by the Standard Subscription. It adds enterprise certified applications to the ownCloud Server, including integration with enterprise services like a File Firewall, SharePoint, Windows network drives, Oracle SQL support and SAML/Shibboleth authentication as well as audit and control tools. The Enterprise Subscription comes with the ownCloud Commercial License and may be modified to include custom services and support to meet the unique needs of the enterprise. It includes access to branding and deployment tools and offers a wider range of support options including up to 24×7 support.
  • You can find a comparison table detailing support options here and enterprise features on this page.

Which solution is best for me?

  • As home or small business user, you benefit from the rich functionality of the ownCloud Server. The documentation as well as community support or support through IT service providers are best suited for your use case.
  • For those who seek file sync and share as provided by ownCloud Server, but want the confidence of knowing that their ownCloud deployment is backed by technical expertise with 8×5 mail support, the Standard Subscription is a cost-effective solution which may meet your requirements.
  • For larger and more complex deployments of ownCloud, servicing hundreds to hundreds of thousands of users, handling terabytes to Petabytes of data, requiring high availability and multi-server scaling, needing integration in Enterprise infrastructure and/or having specific needs around compliance in regulated industries, Enterprise Subscription from ownCloud GmbH is available with 12×5 email and phone support, additional enterprise functionality, deployment and branding tools and more. ownCloud GmbH can also work with you to develop custom support that can include up to 24×7 coverage.
  • Watch the Community and Enterprise Edition Webinar to find out what is best for you.

How do the community and company work together?

  • The company makes it possible for developers to work full time on ownCloud, organizing ownCloud events, marketing ownCloud to a wider audience and supporting companies, governments and schools in their ownCloud deployments.
  • The business model of ownCloud GmbH is very similar to other successful Open Source companies, offering services and support around ownCloud for the enterprise. The company is dedicated to working entirely in the open, accelerating development in the areas of its customers’ needs while enabling a completely open development process where everybody can contribute. See our developer documentation for a description of our development and decision making process.
  • The Enterprise Edition offers additional enterprise applications bundled with ownCloud Server and supported through the Enterprise Subscription. The Standard Subscription and the Enterprise apps become available after a period of additional testing and the addition of enterprise features. ownCloud develops in the open; this is neither an open-core nor a dump-your-code-over-the-wall model. Read what the Free Software Foundation says about it:

Check out and for more information.

What customers does ownCloud GmbH have?

  • ownCloud works with several large enterprises across financial services, energy, government, healthcare, education and more. Some of our marquis customers include TU Berlin, CERN, Joy Global, Wind River, Jefferson National, Geant, De’Longhi, TTX, Dutch Ministry of Defense as well as other large financial services and telco companies we cannot name. Check out the owncloud customer stories for more customers and their testimonials.

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