What Font Does Bluesky Use? Inter, System Fonts, and the AT Protocol

TL;DR: Bluesky uses Inter as its main interface font on the web app (bsky.app). On iOS, posts and bios render in SF Pro. On Android, they render in Roboto. The AT Protocol branding uses its own visual identity. There is no built-in bold, italic, or font picker for posts.

Bluesky has grown from a small invite-only experiment into a real alternative to X, and with that growth comes a question designers and curious users keep asking: what font is that? The answer is straightforward, and because Bluesky is open-source, you can verify it yourself.

The Bluesky web app font: Inter

The primary typeface on bsky.app is Inter, a free and open-source sans-serif designed by Rasmus Andersson. Inter was originally created for computer interfaces, with a tall x-height and open apertures that keep text readable at small sizes on screens. It ships in variable-weight format, covering everything from Thin (100) to Black (900).

If you open bsky.app in a browser and inspect the CSS, the font stack looks like this:

Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif

Inter does the heavy lifting for post text, profile names, navigation labels, and buttons. The system-ui fallbacks exist for situations where Inter has not loaded yet or for characters Inter does not cover.

You can confirm this yourself. Bluesky is built on React Native for Web using the social-app repository on GitHub. The font declarations live in the theme files. Because everything is open-source under the MIT license, there is nothing hidden about the choice.

Why Inter?

Inter is one of the most widely used UI fonts on the web. GitHub uses it. Figma uses it. It became popular because it was purpose-built for interfaces rather than adapted from a print typeface. A few qualities make it a natural pick for a social platform:

• Legibility at small sizes. The tall x-height and generous letter spacing mean short posts, timestamps, and follower counts stay crisp on high-density screens.
• Variable font support. A single variable file covers all weights, so Bluesky can use semibold for usernames and regular for post body without loading multiple font files.
• Free and open-source. Inter is released under the SIL Open Font License, which means zero licensing cost and no usage restrictions. For a startup building an open protocol, that matters.
• Neutral personality. Inter does not call attention to itself. It gets out of the way and lets the content (your posts, images, links) do the talking.

What about the mobile apps?

On mobile, the picture changes. Bluesky's iOS and Android apps are built with React Native, and they lean on the operating system's default font rather than bundling Inter into the app binary.

This means the same post can look subtly different depending on where you read it. SF Pro has rounder terminals and slightly different letter proportions than Inter, so a bio that looks one way on the website may feel a bit different on an iPhone. This is not a bug. It is a standard trade-off in cross-platform development: bundling a custom font into a mobile app adds to the download size and can cause rendering quirks, so most apps let the OS handle it.

If you have used other social platforms, this pattern will look familiar. X (Twitter) does the same thing with Chirp on web and system fonts on mobile, and Mastodon follows a similar approach with Roboto.

The AT Protocol and Bluesky branding

Bluesky the app and the AT Protocol (the decentralized protocol it runs on) are related but separate. The AT Protocol documentation and branding have their own visual identity, distinct from the social app. The Bluesky butterfly logo and wordmark use custom lettering that is not a publicly available font. You will not find it in a font library.

For the app interface itself, though, it is all Inter (on web) and system fonts (on mobile). There is no secret brand typeface hiding behind the scenes.

Can you change the font on Bluesky?

No. Bluesky does not offer a font picker, text formatting toolbar, or any way to choose a typeface for your posts. The compose box is plain text. You type, you post, and the app renders it in whatever font the platform uses on that device.

So how do people post text that looks bold, italic, or styled in unusual ways? The same way they do it on every other platform that lacks native formatting: Unicode look-alike characters.

Unicode includes separate code points for mathematical bold letters (like 𝐁𝐥𝐮𝐞𝐬𝐤𝐲), italic letters, script letters, and dozens of other decorative alphabets. A text generator or font generator converts your plain text into these look-alikes, and you paste the result into Bluesky. The app displays them because they are standard Unicode, not because Bluesky has any special formatting support.

Our Bluesky text formatter is built for exactly this. Pick a style, type your text, copy the output, and paste it into your Bluesky post or bio.

But know the trade-offs before you go wild:

• Screen readers struggle with Unicode styled text. Many assistive technologies skip or mangle these characters. If accessibility matters to you (and it should), use Unicode styling sparingly. We wrote a full breakdown in are Unicode fonts accessible?
• Search does not work. A post written in 𝕌𝕟𝕚𝕔𝕠𝕕𝕖 𝕕𝕠𝕦𝕓𝕝𝕖-𝕤𝕥𝕣𝕦𝕔𝕜 letters will not show up when someone searches for the plain-text version of those words.
• Some characters may not render. If a reader's device lacks the right Unicode block, styled characters can appear as empty boxes. See why fancy text shows as boxes for more on that.
• Hashtags and mentions break. A hashtag written in Unicode bold will not function as a clickable tag.

A bold name in your display name or a single styled word in a bio? Fine. An entire post in cursive Unicode? That is going to hurt readability more than it helps.

How does Bluesky compare to other platforms?

Here is a quick comparison of what font each decentralized or alternative social platform uses:

Bluesky and Mastodon both picked widely available, open-source fonts for their web UIs. X went the custom route with Chirp. All three fall back to system fonts on mobile.

FAQ

What font does Bluesky use? Bluesky uses Inter on its web app (bsky.app). On iOS, posts render in SF Pro. On Android, posts render in Roboto.

Is Inter a free font? Yes. Inter is released under the SIL Open Font License. You can download it, use it in your own projects, and modify it without paying anything.

Can I change the font on my Bluesky posts? No. Bluesky has no font picker or text formatting options. The compose box is plain text. To get styled text, you paste Unicode look-alike characters from a generator like the Bluesky text formatter.

Why does my Bluesky post look different on my phone than on my computer? The web app uses Inter. The mobile apps use your phone's system font (SF Pro on iOS, Roboto on Android). The different typefaces have different letter shapes and spacing, so the same text can look slightly different across devices.

Does Bluesky have bold or italic text? Not natively. There is no formatting toolbar. People use Unicode look-alike characters (e.g. 𝗯𝗼𝗹𝗱 or 𝘪𝘵𝘢𝘭𝘪𝘤) to simulate styled text. These are separate Unicode code points, not actual formatting applied by Bluesky.

Is the Bluesky logo font available to download? No. The Bluesky butterfly logo and wordmark use custom lettering that is not a publicly available typeface.

Can I verify what font Bluesky uses myself? Yes. Bluesky is open-source. You can check the social-app repository on GitHub and inspect the theme/style files to see the font declarations directly.