Mobile operating system
Sailfish OS is a paid Linux-based operating system based on free software, and open source projects such as Mer as well as including a closed source UI. The project is being developed by the Finnish company Jolla.
The OS first shipped with the original Jolla Phone in 2013; while its sale stopped in 2016, it was supplied with software updates until the end of 2020. It also shipped with Jolla Tablet in 2015 and from other vendors licensing the OS. The OS is ported by community enthusiasts to third-party mobile devices including smartphones and tablet computers. Sailfish OS can be used for many kinds of devices.
History and development.
The OS is an evolved continuation of the Linux MeeGo OS previously developed by alliance of Nokia and Intel which itself relies on combined Maemo and Moblin. The MeeGo legacy is contained in the Mer core in about 80% of its code; the Mer name thus expands to MEego Reconstructed. This base is extended by Jolla with a custom user interface and default applications. Jolla and MERproject.org follow a meritocratic system to avoid the mistakes that led to the MeeGo project's then-unanticipated discontinuation. 
The main elements for Sailfish OS 2.0 include:
Software architecture.
The Sailfish OS and the Sailfish software development kit (SDK) are based on the Linux kernel and Mer. Sailfish OS includes a multi-tasking graphical shell called "Lipstick" built with Qt by Jolla on top of the Wayland display server protocol. Jolla uses free and open-source graphics device drivers but the Hybris library allows use of proprietary drivers for Android. Jolla fuzzily stated in 2015 that their goal for Sailfish is to become open source eventually, but some key components of Sailfish OS have been licensed proprietary by Jolla from the start and ever since (as of Sailfish OS 4.5.0.24 in September 2023).
Sailfish OS can run some Android applications through a proprietary compatibility layer.
Targeted device classes.
Sailfish is targeted at mobile devices. Since it inherited around 80% of MeeGo code, Sailfish can be used as a complete general-purpose Linux OS on devices including in vehicle infotainment (IVI), navigation, smart TV, desktops and notebooks, yachts, automotive, e-commerce, home appliances, measuring and control equipment, smart building equipment, etc. See use cases of original MeeGo to compare, and the Devices section for devices that run the Sailfish OS.
Sailfish OS SDK.
The Sailfish OS SDK was announced at the Slush Helsinki conference in 2012, and the alpha was published in February 2013. The SDK, installation and coding tutorials are available for free download from the Sailfish OS website despite the overall license not being open source.
Sailfish SDK uses Qt with VirtualBox for development, compiling and emulation purposes, in contrast to the simulation method. This technique allows compilation on the Sailfish OS and full testing of developed software in the virtual machine, emulating – not simulating – the whole Sailfish OS. This also separates development activities and side effects from everything else running on the host computer, leaving it undisturbed by developments and tests. According to Jolla, development with Sailfish SDK is development on Sailfish OS itself; there are no differences between developed software appearance and behaviour in the SDK and on a device running Sailfish OS.
The availability of source code to the SDK allows shaping and rebuilding to companies' or developers' specific needs, creating a context-specific environment that is set once and needs no preparation when the device is booted. The SDK runs on the operating systems Android, 32- and 64-bit versions of Linux, 64-bit versions of OS X, and Microsoft Windows. It can be used for compiling software for Sailfish OS devices from Linux sources. Its general console/terminal mode follows a commonly used standard. Compatible binaries or libraries can also be used.
Application programming interfaces.
Sailfish OS uses open source Qt APIs (Qt 5, QtQuick 2 etc.) and a proprietary Sailfish Silica for the UI. Standard Linux APIs are provided by the Mer Core.
Sailfish, Ubuntu and Plasma Active have been cooperating to share common APIs. When successful, this will make the platforms compatible on the API level.
Sailfish Browser is the default web browser based on Gecko and using embedlite (also known as IPCLiteAPI), a lite-weight embedding API from Mozilla. Uses proprietary components.
Software overview.
UI supported human languages.
Officially Jolla declares supporting the following 14 languages for the user interface:
Danish, German, English (UK), Spanish, French, Italian, Norwegian, Polish, Portuguese, Finnish, Swedish, Russian, Chinese (mainland), and Chinese (Hong Kong). For each of them, the OS has a dedicated keyboard. There are a few more languages which are unofficially supported by community freelancers not under control by Jolla, hence more than 20 languages are supported in total. Additional languages can be installed by skilled users due to the Linux architecture.
Public "Early access" for beta testers and developers.
After positive experiences with pushing early updates to a small group of opt-in users for Sailfish Update 9 and for the connectivity hotfix, Jolla has allowed all interested parties to try a new version of Sailfish OS about 1–2 weeks before official release, in a program called "Early access". It is expected to be useful for developers and technically minded users, and a step towards more community integration into the Sailfish release process, including improvement of quality by identifying critical issues which only show up in certain environments or device setups, before rolling the update out to the wider user audience. As an added bonus, it provides a window for developers to test their applications on new releases of Sailfish OS.
In the long term it will help Jolla to establish a developer program with early release candidate access for registered developers, and to have more community involvement in platform development. The first detail Jolla is hoping to learn from this is how it can gather feedback from a large audience in a reasonable way.
Basic details about the early access update:
Version history.
Sailfish OS has three naming conventions: version number, update number and version name.
Stop releases.
When updating an installed Sailfish OS from an earlier release, for example after device factory reset, there are several stop releases which must not be skipped and have to be installed before continuing on the path to subsequent releases. These releases provide new functionality that is not compatible with previous releases and have to be traversed in order not to put the Sailfish OS installation into an unstable state.
Porting.
The Sailfish website publishes an online compendium of knowledge, links and instructions on porting issues.
Using Android software running on Sailfish OS.
In addition to its native applications, Sailfish can run some Android applications by installing them from an application store or directly through an APK file. Supported Android versions are 4.1.2 "Jelly Bean" on the original Jolla phone; 4.4.4 "Kit-Kat" on the Jolla C, Jolla tablet and Xperia X; 8.1.0 "Oreo", 9 "Pie" and 10 (depending on the Sailfish OS release) on Xperia XA2, Xperia 10 and Xperia 10 II. Problems can arise if these applications were built without following Android standards about controls, which might not display correctly and so become unusable.
Sailfish OS uses Alien Dalvik, a proprietary Android compatibility layer. It does not emulate Android, but instead implements its APIs by adapting the Android Open Source Project (AOSP) code to run as an application. Android applications can thus run at native speed without any perceivable slow-down. Sailfish can run both native Sailfish and Android software simultaneously, with the user switching between them on the fly.
Starting with Alien Dalvik 8.1 (also called "Android App Support" since then), it uses LXC to improve security by better isolation, in the same way the open source Android compatibility layer Anbox is doing.
Hardware overview.
Advantages of the Mer standard.
Sailfish OS can be used on any hardware with Linux-kernel support and compatible with the middleware utilising the Mer core. Community enthusiasts have ported Sailfish OS to a number of devices this way. Instead of designation to a specific reference hardware platform, a VirtualBox implementation with the Sailfish SDK is available for development on Linux, OS X and Windows operating systems. This virtual machine implementation contains the whole Sailfish OS isolated from local resources and the local OS to enable convenient evaluation of the behaviour and performance of coded or ported software before deployment on real devices.
Devices from other vendors licensing Sailfish OS.
Manufacturers can provide mobile equipment with a licensed Sailfish OS, or as open source, or combining both and including their own or the operator's modifications and branding for specific markets or purposes.
Community enthusiasts' ports to devices from other vendors.
Due to the relative ease of porting and the open source license, Sailfish OS has also been unofficially ported to other 3rd-party devices. The Hardware Adaptation Development Kit for porters has been published and is free. These ports are mostly published on the Maemo and XDA Developers forums, and in the Mer wiki a list of the ports is compiled. Due to license restrictions, proprietary parts or extensions such as the Alien Dalvik compatibility layer for Android apps are not included. However they can be added, e.g. when a manufacturer or distributor turns it from the community version into an officially supported version for a particular device. From the originally more than 80 ports, there are about 19 ports that are still in active development – as of March 2019 – meaning they have been updated to Sailfish 3:
To display the ease of porting Sailfish OS to other devices, Jolla showed created ports and community ports at events like the Mobile World Congress, Slush and FOSDEM:
OS development status.
Sailfish OS is promoted by Jolla and supported by the open Sailfish Alliance established in 2011, a group established to unite OEM and ODM manufacturers, chipset providers, operators, application developers and retailers. On 16 August 2012, the user interface was reported to be ready for release. Jolla's CEO Jussi Hurmola stated in a ZDNet interview, " ... Our UI is ready now, we haven't released it yet, we will save it for the product launch and the platform is getting up now so the project looks pretty nice".
The next day, Jolla's CEO Marc Dillon said on social networking website Twitter that the company had reached the first development target. Sailfish was debuted by the Jolla team, including a worldwide internet stream, as a demo of the OS, and the UI and SDK during the Slush event in Helsinki, Finland, on 21–22 November 2012. The alpha stage of Sailfish OS SDK was published at the end of February 2013 and was made available for free download.
On 16 September 2013, Jolla announced that its OS had been made compatible with Android applications and hardware. The first telephone to use it was launched on 27 November 2013 at a pop-up DNA Kauppa shop in Helsinki. The first 450 telephones were sold at this event, while the rest of the preordered devices were shipped shortly after.
In August 2015, version 1.1.9 "Eineheminlampi" was released, which added the main elements of the revamped Sailfish OS 2.0 user interface.
Sailfish OS 2.0.0 was launched with the Jolla Tablet, and existing devices, both smartphones and tablets, from Jolla's official distribution channels are supported with upgrade to Sailfish OS 2.0.0 and following updates.
In May 2016 Jolla announced the Sailfish Community Device Program, supporting developers and members of Sailfish OS community.
Aurora OS.
Jolla staff met with members of the Russian technology community to break ground on the new software and promote Sailfish OS, as part of Jolla's BRICS strategy. As a result of those efforts, on 18 May 2015 the Russian minister of communications Nikolai Nikiforov announced plans to replace Apple's iOS and Google's Android platforms with new software based on Sailfish. He intends it to cover 50% of Russian needs in this area during next ten years, in comparison to the 95% currently covered with western technology. The Russian version is currently being developed under the brand name Mobile OS "Aurora" (мобильная ОС «Аврора»), before 2019 as "Sailfish Mobile OS RUS". The Chinese multinational technology company Huawei was in talks with the Russian Ministry of Communications to install Aurora OS on tablets for Russia’s population census by August 2020.
Jolla has cut business ties with Russia in 2021.
Sailfish Alliance.
Sailfish Alliance is the open alliance established in 2011 by Jolla company to support the MeeGo ecosystem with new products, services and business opportunities around or using Sailfish OS, a Linux operating system combining Mer with proprietary components from Jolla and other parties, for various purposes and mobile devices.
The alliance is seen as a competitor to other groups like