Drop an .html into Slack and it's just a download. Instead, publish it and paste the link: the unfurl shows your branded preview card, and clicking opens the rendered page.
Paste a branded link
drop report.html → paste the URL into Slack → your OG card renders. A native /drop command is on the roadmap.
FAQ
Is it really open-source and self-hosted?
Yes — MIT licensed, and it runs on your own Vercel Blob + domain. No third party ever holds your content (it's encrypted client-side) or controls your URL.