TriggerTrelloReal-timeUpdated May 2026
How do I trigger when a Trello attachment is added?
Short answer: Drop the "Trello → Attachment Added" trigger on your workflow canvas, add filters if you want them, and publish. It fires within seconds of the event in Trello, not on a polling schedule.
Anatomy
What this trigger looks like in a workflow.
Drop it on the canvas. Configure a couple of fields. Publish.
In the builder
Trigger
Attachment Added
When the matching event happens
when an attachment is added to a cardon attachment addednew attachment addedwatch for attachment addedwhen attachment added
What this trigger returns
for the curiousYou don’t need to read this. Tiny Command auto-maps every field into the visual picker so downstream nodes can pull values by clicking. We show it here for power users who want to know what’s on the wire.
{"card": "Sample Card","board": "Project Board","event": "addAttachmentToCard"}
Output shape
Fields available to downstream nodes.
Every field below can be referenced by name in any action or filter that comes after this trigger.
| Field | Type | Example |
|---|---|---|
| card | string | "Sample Card" |
| board | string | "Project Board" |
| event | string | "addAttachmentToCard" |
Pairs with
Drop these actions after Attachment Added.
FAQ
Questions about Attachment Added.
How does the Attachment Added trigger work in Trello?
Fires when an attachment is added to a Trello card. Use to copy the file to S3/Drive for backup, virus-scan, or to extract text for downstream processing.
Is the Attachment Added trigger real-time?
Yes. Attachment Added uses webhooks or push subscriptions, not polling. Your workflow fires within seconds of the event happening in Trello.
What data does Attachment Added return?
The full event payload from Trello. The output shape table on this page lists every field, its type, and an example value so you can map fields into downstream nodes.
Can I filter Attachment Added so only some events start a workflow?
Yes. Add a Filter node right after the trigger and match on any field, whether that's subject, sender, status, or anything else in the payload. Workflows only continue when the filter passes.
Do I need Trello admin permissions to use Attachment Added?
For most Trello accounts a standard user can authorize the trigger. Some Trello plans require an admin to enable third-party webhooks. Check Trello's docs if the trigger fails to register.
More triggers
Other Trello triggers.
Trigger
New Card
Fires when a new card is created on a Trello board. The standard inbound hook for AI triage, auto-assignment, or external mirroring.
TriggerCard Moved
Fires when a card is moved between lists on a Trello board (the classic Kanban-stage-change event). Use to celebrate completion, log cycle-time, or kick off downstream work.
TriggerCard Updated
Fires whenever any field on a Trello card changes (name, description, due date, labels, members, custom fields). Combine with a field filter to react only to specific changes.
TriggerComment Added
Fires when a comment is added to a Trello card. Use to mirror discussion to Slack, alert the assignee, or extract AI sentiment.
TriggerNew List
Fires when a new list is created on a Trello board. Useful for templated board provisioning or governance audit logs.
Build a workflow on this trigger.
One trigger. 21+ downstream actions. Zero glue.
