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Block Kit

Block Kit is a UI framework that offers a balance of control and flexibility when building experiences in messages and other surfaces on Slack.

Customize the order and appearance of information and guide users through your app's capabilities by composing, updating, sequencing, and stacking blocks — reusable components that work almost everywhere in Slack.

Take a tour of the available blocks, get started with an app template, or dig into the documentation.

Block Kit Builder

Shuffle and stack blocks to quickly prototype messages and views on Slack. When you're ready, we'll provide the payload so all you have to do is copy and paste it into your app's code.

Design with Block Kit Builder.

Block Kit Builder Block Kit Builder
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Spend less time designing your app by starting with a template. Developed around common workflows in Slack, such as approvals, notifications and polls, templates makes designing apps simpler.

Get started with templates.


Explore our documentation and learn how to develop apps with Block Kit. Discover best practices for creating engaging user experiences, understand which APIs support our newest platform features, and use developer tools to simplify building your app.

Learn about composing messages.

Block Kit Builder Block Kit Builder