All will be revealed

Build a richer experience for your users in Slack with app unfurls

Slack API
Slack Platform Blog


If you’ve ever shared a link in Slack and seen it expand with a photo or other metadata, then you’re already familiar with unfurls. Unfurls add important context to the millions of links teams share in Slack every day, saving people a click by helping them understand why a link was shared and whether they need to act on it.

Starting today, we’re giving you the ability to build custom unfurls for any link in Slack — most importantly, links to your app. With app unfurls, you can add context to links with message attachments and facilitate micro-workflows using message buttons, turning links into an opportunity to give people the best possible experience with your app.

Two main things differentiate app unfurls from the unfurls you already know. First, a new flow makes it possible for you to unfurl “authenticated” content, like CRM information, project management issues, or design wireframes. App unfurls also give you the freedom to unfurl domains other than your own, so you can build custom previews for the tools your team uses.

Preview authenticated information

With regular unfurls, Slack automatically creates an unfurl based on information found in that page’s metadata. With app unfurls, you have more control. Not only can you customize how links to public domains appear, but you can also bring in “authenticated” content, previewing information that previously couldn’t be unfurled in Slack.

Our events API will send you an event which you can act on by kicking off an OAuth path for your app to recognize the link sharer as a user. For example, take an analytics product like Periscope Data. Without app unfurls, a link in Slack to one of their dashboards remains just that — a plain URL. Nothing can unfurl because their app can’t tell whether the person sharing it has permission to view the content.

But with app unfurls, Periscope Data can recognize a person in Slack as a user of its own service. They can reveal the dashboard inside Slack, delivered in context alongside a team’s other work.

Make unfurls interactive

You can also make unfurls actionable with hyperlinks or message buttons that can fire off a variety of functions with your app.

For example, let’s look at Glitch, a new coding community where people can build on and “remix” projects that then get deployed instantly to the cloud.

When someone links to a Glitch project in Slack, that link expands to give people three options for working with the code in that project. Teams get to choose from these direct calls to action, increasing engagement with Glitch and saving time in the process.

Can I build custom unfurls for my team?

Beyond unfurling your own app, you can also use app unfurls to bridge tools your team frequently uses. For instance, imagine you’re on a team that receives and triages customer support tickets. You can rely on notifications from Slack’s events API to know when people link to those tickets. Then, you can build an unfurl that previews important ticket information and adds the option to convert it into a report in your company bug tracker. Simple.

How to start

We’ve made sure our SDKs support app unfurls today. Learn how to build an interactive unfurl and how to take advantage of app unfurls on our documentation site.

Are you using app unfurls to help your team get work done? We want to hear your story. Send us a note at

Illustration by Pete Ryan



Slack API
Slack Platform Blog

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