Sync files, screenshots and inline images between Jira and Slack
Screenshots are where triage actually happens — the stack trace, the broken UI, the log snippet. Threadmaker syncs file attachments both ways between a Jira comment and its Slack thread, and renders images inline in the Jira comment body so reviewers see them without opening a separate tab.
Add Threadmaker to Slack — free for up to 10 Jira users.
How attachment sync works
- Slack → Jira: files attached to a Slack reply land as attachments on the matching Jira comment.
- Jira → Slack: files attached to a Jira comment arrive as separate file-share messages in the Slack thread, paired with the parent comment.
Inline images
Any file type syncs as an attachment. Images — PNG, JPEG, JPG, GIF, or WebP — additionally render inline in the comment body, not just in the Attachments tab. SVG and other formats sync too but aren't inlined for security reasons; they appear as regular attachments.
The limit: 3.5 MB per file
Threadmaker forwards file bytes through the Cloudflare Workers and Atlassian Forge proxies, which have fixed body-size budgets — so each file can be up to 3.5 MB, any file type, in either direction. A comment carries up to ten files, up to two of them large (2–3.5 MB). On Slack→Jira the smaller files (each up to 2 MB) share a per-comment budget of about 2 MB, and the two large slots are separate from that pool. Oversized or excess files are dropped, and Threadmaker flags it where it can — an ephemeral warning to the uploader on Slack→Jira, and an optional in-thread note a project admin can enable on Jira→Slack. It's best-effort: a failed file upload never aborts the comment, so the text still syncs. For files larger than that, upload to your team's storage and paste a link in the comment instead.
FAQ
Do attachments sync when I edit a message? Yes — adding a file while editing a synced message or comment propagates, within the same 3.5 MB per-file cap. Removing a file does not retract the copy already synced to the other side; delete the whole message or comment to retract it.
What happens to a file over 3.5 MB? On the Slack→Jira path it's dropped and the uploader gets an ephemeral heads-up. On the Jira→Slack path the oversize file is left behind too, but a project admin can turn on an optional in-thread note ("📎 N of M attachments synced") that points back to the Jira issue — off by default. Either way the comment text still syncs; only the oversize file is left behind.
Can I sync a whole folder or a video? No — the proxy budgets are sized for triage artifacts (screenshots, log snippets, small PDFs and CSVs). Link out to your storage for anything larger.
Related
Full reference in the setup guide. See also edits and deletes, @-mention mapping, and live status in the thread — or read the engineering-triage playbook, which leans on inline screenshots. Back to all features.
Ready to try it?