Slack Block Kit

UI framework for building rich, interactive layouts in Slack messages, modals, and App Home.

CRITICAL: Two Markup Systems

Text inside Block Kit text objects uses Slack mrkdwn syntax (*bold*, <url|text>), NOT standard Markdown. The only exception is the markdown block, which accepts standard Markdown (**bold**, [text](url)). Mixing these up is the single most common Block Kit generation error.

Quick Decision Trees

"Should I use blocks?"