Note: We have recently updated our system font stack in August 2022 to better support future Android and more Linux desktop environments.

As what a co-founder of Signal said, aesthetics are important in computer software. We take that word seriously when deciding whether to use custom fonts or not on our website.

Traditionally, our websites used a lot of custom fonts. No, really. I still remembered the days building our Instagram knock-off using 5 distinct web fonts: Pacifico, Montserrat, Source Sans Pro, Fira Sans, and Aileron.

Before redesigning this website to use the all-new Twenty Twenty-Two theme, we heavily used JetBrains Mono for everything. Because 2021 was the year when we encourage people to not just code, but also speak in code.

This year, however, should be the celebration of the diversity of computer software and systems all around the world. You know, #InterfaceInPolymorphism, our famous slogan which lets many search engines to give a premium red carpet path for you to walk into this specific site.

Of course, one of the best ways to capture the diversity of computer systems is by using the (in)famous system font stack:

font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;

This combination has been used in many sites. Including GitHub, which notably removes Roboto from the list due to rendering issues on some Linux operating systems. Note that Android users visiting the GitHub website today will still see Roboto font being used as they don’t have Helvetica or Arial installed.

And again, we ended up rearranging and use this specific stack instead:

font-family: "Segoe UI Variable Text", -apple-system, BlinkMacSystemFont, Inter, "Segoe UI", Cantarell, "Open Sans", "Noto Sans", Ubuntu, Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji"

What this font-family mess is all about.

font-family is a CSS property which lets you declare which fonts to use on specific parts of the website. And yes, font-family is also one of the oldest properties ever introduced in the history of CSS! font-family is even supported in Internet Explorer 3, released in 1996

Here, both -apple-system and BlinkMacSystemFont are used solely to load San Fransisco (or SF Pro), the system font for Apple products today including iOS, iPadOS, and macOS. "Segoe UI" refers to Segoe UI, the system font for Microsoft Windows since the age of Windows Vista. And finally, Roboto, which refers to Roboto, the default sans-serif font for Android and Chrome OS.

Wait, why not just use 3 fonts then Arial, Helvetica, sans-serif?

Even though these 3 fonts (San Fransisco, Segoe UI, Roboto) seem to cover most of modern operating systems today by market share (Android, Chrome OS, iOS, iPadOS, macOS, Windows), we haven’t yet talked about another great family of operating systems: Linux.

Despite having its low desktop market share (thanks to enterprises sticking to Windows as well as those Apple fanboys), Linux is still considered one of the most popular operating systems to date, powering everything from embedded devices up to 500 out of 500 top supercomputers in the world!

It wouldn’t be fair if the voice of Linux distributions are unheard on this website. Because remember, “Interface in Polymorphism” doesn’t just belong for mainstream and popular computer systems such as Windows or Microsoft Office.

We believe that by supporting a diverse community of computer systems, we will benefit a more diverse community of computer users today, which are well, human beings. Hence “Interface in Polymorphism” should belong to everyone, just like the diversity of people today.

Interface for the minority of desktop operating systems.

Now here’s the question, what is the system font for Linux (and perhaps others like Haiku or BSD)? The answers is many, depending on distros and desktop environments. To simplify this answer, let’s look at the original, recommended set of system font stack:

font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;

Here, Oxygen was chosen to cater Linux distros running the KDE Plasma 5 desktop environment. However, in 2016 the KDE community decided to replace it with Google’s Noto Sans, presumably to better support non-Latin alphabet letters, just like this case for Cyrillic.

Then we have Cantarell, the system font for the GNOME desktop environment. And here, I can see why Cantarell is placed after Ubuntu (more on that later), as earlier versions of Cantarell are very, very, ugly.

Since then the same font has been improvised to look even better, and now also available in different weights (e.g. Light or Extra Bold). The official website of Purism shows how good is Cantarell today.

Finally, as what the name states, “Ubuntu” refers to the Ubuntu font primarily used in Ubuntu, one of the most popular Linux distro. Despite being a Linux fan, I’m not actually a fan of the font itself and prefer to replace it with Cantarell on my Linux installations.

One designer talked about how Ubuntu performs the best amongst legacy macOS system fonts (Lucida Sans and Helvetica Neue) when it comes to legibility and (un)ambiguity:

No need to argue, Helvetica is not the most legible. However it’s remarkable how well Ubuntu performs in the above screenshot. Especially an interface typeface has to provide enough distinction between its various glyphs. Think about passwords, user names, data tables, drop down lists… Your interface must display them in an unambiguous way. You don’t want your users to pause for even a fraction of a second to decipher glyphs and shapes.

“The Best UI Typeface Goes Unnoticed” by Thomas Byttebier, 2015.

Sure, “Interface in Polymorphism” should account the diversity of desktop OSes, but the same phrase should also account the diversity of desktop environments, including GNOME, KDE, Budgie, Pantheon, MATE, LxQt, Cinnamon, and so on.

However, looking at Stack Exchange / StackOverflow’s and Firefox’s perspective for the system font stack, I’m personally afraid that developers will generalize Ubuntu as the default system font for any Linux distribution – which we shouldn’t.

The “perfect” set of system fonts.

Again, let me show you again our great system font stack:

font-family: "Segoe UI Variable Text", -apple-system, BlinkMacSystemFont, Inter, "Segoe UI", Cantarell, "Open Sans", "Noto Sans", Ubuntu, Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji"

Here, you’ve seen why I included -apple-system, BlinkMacSystemFont, Segoe UI, and Roboto. But what about the others?

But first, where’s ui-sans-serif and system-ui?

Well, they’re not in the list due to some concerns when it comes to web browser’s decisions to choose the right system font in Linux. But more on that later

For Windows.

font-family: “Segoe UI Variable Text”, -apple-system, BlinkMacSystemFont, Inter, “Segoe UI”, Cantarell, “Open Sans”, “Noto Sans”, Ubuntu, Roboto, Helvetica, Arial, sans-serif, “Apple Color Emoji”, “Segoe UI Emoji”, “Segoe UI Symbol”, “Noto Color Emoji”

One of the new additions to this font stack is Segoe UI Variable, the new system font for Windows 11. The new font really matters to me as I’m also a hater of the original font while liking this new one. Here’s why:

If you look closely at the above image, the new Segoe UI Variable font characters matches the style of Inter, aka. the “open-source, cheap free clone of Apple’s San Fransisco”. Yeah, developers today really love and using it everywhere; you can see Inter being used everywhere today from GitHub to Mozilla and everywhere.

For Android, iOS, iPadOS, and macOS.

font-family: “Segoe UI Variable Text”, -apple-system, BlinkMacSystemFont, Inter, “Segoe UI”, Cantarell, “Open Sans”, “Noto Sans”, Ubuntu, Roboto, Helvetica, Arial, sans-serif, “Apple Color Emoji”, “Segoe UI Emoji”, “Segoe UI Symbol”, “Noto Color Emoji”

Nothing’s different here, as Android users will get Roboto and Apple users will get what they want. However, we dropped Helvetica Neue and Lucida Grande from the stack since we feel most of the Apple devices today run the latest operating systems. As a reference, San Fransisco is available on iOS 9 and later as well as macOS / OS X El Capitan (10.11).

Note: If we included both of them on the stack, well we must put Tahoma, too!

However, there are two specific reasons why Roboto is included almost at the end of the stack, sitting next to Helvetica and Arial. First is because we’d like to favor Linux distributions’ preferred system fonts other than Roboto (e.g. Open Sans or Cantarell), and we decided to load Roboto from Google Fonts instead to provide compatibility with on pre-Android Lollipop (5.0) devices.

For Linux (and other Unix-like) distributions.

font-family: “Segoe UI Variable Text”, -apple-system, BlinkMacSystemFont, Inter, “Segoe UI”, Cantarell, “Open Sans”, “Noto Sans”, Ubuntu, Roboto, Helvetica, Arial, sans-serif, “Apple Color Emoji”, “Segoe UI Emoji”, “Segoe UI Symbol”, “Noto Color Emoji”

Last year, the LinuxQuestions.org forum posted an annual poll on the “Desktop Environment of the Year”. And here, we’re seeing KDE being the winner just right before XFCE. As I mentioned before, KDE now uses Noto Sans by default so potting it into a stack is a must.

Then, the voters also greatly voted GNOME which uses Cantarell by default (except for Ubuntu Desktop users which uses the Ubuntu font instead). By including Cantarell before Ubuntu, GNOME users outside the Ubuntu Desktop can comfortably visit our website with the matching system font as theirs. We believe this will benefit those Fedora, Trisquel, or even Purism fans out there!

And lastly, we also included Inter and Open Sans to the stack, as they are often set by some distros as their system font:

• elementary OS: Inter, previously Open Sans
• KDE Neon: Noto Sans (follows KDE Plasma defaults)
• Purism PureOS: Cantarell (follows GNOME defaults)
• Linux Lite: Noto Sans, despite some are using Roboto
• Linux Mint: Noto Sans
• Raspberry Pi OS / Raspbian: Roboto Piboto, see Update 1
• Ubuntu: Ubuntu
• Zorin OS: Inter

Oh wait, these selection of system fonts are ready to support other Linux based operating systems, too!

• KaiOS: Noto Sans
• KDE Plasma Mobile: Noto Sans (follows KDE Plasma defaults)
• PureOS Mobile / Phosh: Cantarell (follows GNOME defaults)

That’s it. Have fun!

Yeah, that’s the end of this post. As you can see, this is just a beginning of something I tried to achieved: cyber multiculturalism. If you are Indonesian and understood what multiculturalism is, I’m currently bringing that to the realm of today’s computer systems.

Enjoy reading our apps and articles in the most native possible way!

Update 1: August 6, 2022

We decided to introduce three new fonts to our system font stack. First is of course, Roboto Flex. We included them just before Roboto to let future Android devices have a piece of mind while still honoring Linux users’ of choice.

Next is Piboto, the Raspberry Pi’s actual system font because the designer behind the Raspberry Pi desktop disliked the aesthetics of the newer Roboto font.

Including Piboto, yeah, just right before Ubuntu, Roboto Flex, and Roboto, liberates Raspberry Pi devices to use their proudful system font without having to re-download Roboto as a webfont which may affect their web browsing performance. What a win-win solution for both of us!

Note: While Piboto itself is aesthetically similar to Roboto as on pre-Lollipop Android devices, the version of Piboto included on Raspberry Pi desktop ranges to Light to Black by default, compared to just Regular and Bold versions on those old Android devices.

And finally, GNU FreeSans. Preinstalled on 99.99% Linux desktop distributions, that we consider it as our last line of defense to let Linux desktops who retaliate from using Roboto webfonts to finally choose a better font than Bitstream Vera Sans or DejaVu Sans, which both kinda look like Verdana but their bold version is so wide that they may break our user interface as compared to all the other fonts.

GNU FreeSans will be placed after Helvetica and before Arial and the generic “sans-serif” due to the font’s similar aesthetics with Helvetica. So finally, our system font stack has just grown into:

font-family: "Segoe UI Variable Text", -apple-system, BlinkMacSystemFont, Inter, "Segoe UI", Cantarell, "Open Sans", "Noto Sans", Piboto, Ubuntu, "Roboto Flex", Roboto, Helvetica, FreeSans, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji"