Add Reaction: Slack action

Inputs

The fields this action accepts.

Every field can be mapped from an upstream trigger, AI step, table row, or hard-coded literal.

Field	Type	Required	Description
Channel channel	string	Required	Slack channel ID (starts with C for public, G for private group, D for DM). Find via List Channels. Not the channel name with #.
Message Timestamp timestamp	string	Required	The 'ts' value of the message to react to
Emoji Name name	string	Required	Emoji name without colons (e.g. thumbsup, not :thumbsup:)

Sample request

{
  "channel": "C1234567890",
  "timestamp": "1234567890.123456",
  "name": "e.g. thumbsup"
}

Returns

{
  "ok": true
}

Use these fields in downstream nodes for routing, logging, or error handling.

FAQ

Questions about Add Reaction.

What does the Add Reaction action do in Slack?

Adds an emoji reaction to a Slack message. Lightweight ack mechanism for bots, or used to seed a reaction-voting message.

What inputs does Add Reaction require?

Required: Channel, Message Timestamp, Emoji Name. Every input accepts a static value or a variable from any upstream node in your workflow.

Can I use dynamic inputs from earlier workflow nodes?

Yes. Any field on this action can pull values from upstream nodes, whether that's a form response, a trigger payload, an AI output, or a lookup result.

What happens if Slack returns an error?

The workflow pauses on the failed node, the error message is captured in the run log, and you can retry the run with one click. Auto-retry policies are configurable per workflow with exponential backoff up to 5 attempts.

Does Add Reaction support batch operations?

Yes. Run Add Reaction inside a Loop node to process arrays. Tiny Command handles Slack's rate limits automatically so you don't have to throttle manually.

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