Slack's Reactions API lets apps programmatically manage emoji reactions on messages and files, making it easy to capture lightweight feedback like approvals, acknowledgments, or votes. Through Web API methods (reactions.add, reactions.remove, reactions.get, reactions.list) and the Events API (reaction_added and reaction_removed), apps can add or delete reactions, read which reactions are on an item, and monitor reaction activity in real time.
openapi: 3.1.0
info:
version: "1.0"
title: Slack Reactions API
description: "Slack\x19s Reactions API lets apps programmatically manage emoji reactions on messages and files, making it easy to capture lightweight feedback like approvals, acknowledgments, or votes.
Through Web API methods (reactions.add, reactions.remove, reactions.get, reactions.list) and the Events API (reaction_added and reaction_removed), apps can add or delete reactions, read which reactions
are on an item, and monitor reaction activity in real time. It works with messages (including threads), files, and file comments in channels, DMs, and group DMs where the app has access. Responses include
reaction names, counts, and user IDs, and support both standard and custom emoji. Proper scopes (reactions:read and reactions:write, plus relevant conversation/file scopes) and channel visibility rules
apply, rate limits are enforced, and each user can apply at most one instance of a given emoji per item."
paths:
/reactions.add:
post:
tags:
- Add
- Post
- Reactions
description: Adds a reaction to an item.
externalDocs:
description: API method documentation
url: https://api.slack.com/methods/reactions.add
operationId: postReactionsAdd
parameters:
- name: token
in: header
description: 'Authentication token. Requires scope: `reactions:write`'
required: true
schema:
type: string
requestBody:
content:
application/x-www-form-urlencoded:
schema:
required:
- channel
- name
- timestamp
type: object
properties:
channel:
type: string
description: Channel where the message to add reaction to was posted.
name:
type: string
description: Reaction (emoji) name.
timestamp:
type: string
description: Timestamp of the message to add reaction to.
application/json:
schema:
required:
- channel
- name
- timestamp
type: object
properties:
channel:
type: string
description: Channel where the message to add reaction to was posted.
name:
type: string
description: Reaction (emoji) name.
timestamp:
type: string
description: Timestamp of the message to add reaction to.
required: true
responses:
'200':
description: Typical success response
content:
application/json:
schema:
title: reactions.add schema
required:
- ok
type: object
properties:
ok:
$ref: '#/components/schemas/defs_ok_true'
additionalProperties: false
description: Schema for successful response from reactions.add method
example:
ok: true
default:
description: Typical error response
content:
application/json:
schema:
title: reactions.add error schema
required:
- error
- ok
type: object
properties:
callstack:
type: string
description: 'Note: PHP callstack is only visible in dev/qa'
error:
type: string
enum:
- bad_timestamp
- message_not_found
- no_item_specified
- invalid_name
- already_reacted
- too_many_emoji
- too_many_reactions
- not_authed
- invalid_auth
- account_inactive
- no_permission
- invalid_arg_name
- invalid_array_arg
- invalid_charset
- invalid_form_data
- invalid_post_type
- missing_post_type
- team_added_to_org
- invalid_json
- json_not_object
- request_timeout
- upgrade_required
ok:
$ref: '#/components/schemas/defs_ok_false'
additionalProperties: false
description: Schema for error response from reactions.add method
example:
error: already_reacted
ok: false
security:
- slackAuth:
- reactions:write
summary: Slack Post Reactions Add
x-api-evangelist-processing:
GenerateOperationSummariesFromPath: true
PascalCaseOperationSummaries: true
CaselCaseOperationIds: true
ChooseTags: true
x-microcks-operation:
delay: 0
dispatcher: FALLBACK
/reactions.get:
get:
tags:
- Get
- Reactions
description: Gets reactions for an item.
externalDocs:
description: API method documentation
url: https://api.slack.com/methods/reactions.get
operationId: getReactionsGet
parameters:
- name: token
in: query
description: 'Authentication token. Requires scope: `reactions:read`'
required: true
schema:
type: string
- name: channel
in: query
description: Channel where the message to get reactions for was posted.
schema:
type: string
- name: file
in: query
description: File to get reactions for.
schema:
type: string
- name: file_comment
in: query
description: File comment to get reactions for.
schema:
type: string
- name: full
in: query
description: If true always return the complete reaction list.
schema:
type: boolean
- name: timestamp
in: query
description: Timestamp of the message to get reactions for.
schema:
type: string
responses:
'200':
description: Typical success response
content:
application/json:
schema:
title: reactions.get success schema
type: array
description: Schema for successful response from reactions.get method
example:
file:
channels:
- C2U7V2YA2
comments_count: 1
created: 1507850315
groups: []
id: F7H0D7ZA4
ims: []
name: computer.gif
reactions:
- count: 1
name: stuck_out_tongue_winking_eye
users:
- U2U85N1RV
timestamp: 1507850315
title: computer.gif
user: U2U85N1RV
ok: true
type: file
default:
description: Typical error response
content:
application/json:
schema:
title: reactions.get error schema
required:
- error
- ok
type: object
properties:
callstack:
type: string
description: 'Note: PHP callstack is only visible in dev/qa'
error:
type: string
enum:
- bad_timestamp
- file_not_found
- file_comment_not_found
- message_not_found
- no_item_specified
- not_authed
- invalid_auth
- account_inactive
- no_permission
- invalid_array_arg
- invalid_charset
- invalid_form_data
- invalid_post_type
- missing_post_type
- team_added_to_org
- invalid_json
- json_not_object
- request_timeout
- upgrade_required
ok:
$ref: '#/components/schemas/defs_ok_false'
additionalProperties: false
description: Schema for error response from reactions.get method
example:
error: invalid_auth
ok: false
security:
- slackAuth:
- reactions:read
summary: Slack Get Reactions Get
x-api-evangelist-processing:
GenerateOperationSummariesFromPath: true
PascalCaseOperationSummaries: true
CaselCaseOperationIds: true
ChooseTags: true
x-microcks-operation:
delay: 0
dispatcher: FALLBACK
/reactions.list:
get:
tags:
- Get
- Lists
- Reactions
description: Lists reactions made by a user.
externalDocs:
description: API method documentation
url: https://api.slack.com/methods/reactions.list
operationId: getReactionsList
parameters:
- name: token
in: query
description: 'Authentication token. Requires scope: `reactions:read`'
required: true
schema:
type: string
- name: user
in: query
description: Show reactions made by this user. Defaults to the authed user.
schema:
type: string
- name: full
in: query
description: If true always return the complete reaction list.
schema:
type: boolean
- name: count
in: query
schema:
type: integer
- name: page
in: query
schema:
type: integer
- name: cursor
in: query
description: >-
Parameter for pagination. Set `cursor` equal to the `next_cursor`
attribute returned by the previous request's `response_metadata`.
This parameter is optional, but pagination is mandatory: the default
value simply fetches the first "page" of the collection. See
[pagination](/docs/pagination) for more details.
schema:
type: string
- name: limit
in: query
description: >-
The maximum number of items to return. Fewer than the requested
number of items may be returned, even if the end of the list hasn't
been reached.
schema:
type: integer
responses:
'200':
description: Typical success response
content:
application/json:
schema:
title: reactions.list schema
required:
- items
- ok
type: object
properties:
items:
type: array
items:
type: object
ok:
$ref: '#/components/schemas/defs_ok_true'
paging:
$ref: '#/components/schemas/objs_paging'
response_metadata:
$ref: '#/components/schemas/objs_response_metadata'
additionalProperties: false
description: Schema for successful response from reactions.list method
example:
items:
- channel: C3UKJTQAC
message:
bot_id: B4VLRLMKJ
reactions:
- count: 1
name: robot_face
users:
- U2U85N1RV
subtype: bot_message
text: 'Hello from Python! :tada:'
ts: '1507849573.000090'
username: Shipit Notifications
type: message
- comment:
comment: This is a file comment
created: 1508286096
id: Fc7LP08P1U
reactions:
- count: 1
name: white_check_mark
users:
- U2U85N1RV
timestamp: 1508286096
type: file_comment
user: U2U85N1RV
file:
channels:
- C2U7V2YA2
comments_count: 1
created: 1507850315
reactions:
- count: 1
name: stuck_out_tongue_winking_eye
users:
- U2U85N1RV
title: computer.gif
user: U2U85N1RV
username: ''
- file:
channels:
- C2U7V2YA2
comments_count: 1
created: 1507850315
id: F7H0D7ZA4
name: computer.gif
reactions:
- count: 1
name: stuck_out_tongue_winking_eye
users:
- U2U85N1RV
size: 1639034
title: computer.gif
user: U2U85N1RV
username: ''
type: file
ok: true
response_metadata:
next_cursor: dGVhbTpDMUg5UkVTR0w=
default:
description: Typical error response
content:
application/json:
schema:
title: reactions.list error schema
required:
- error
- ok
type: object
properties:
callstack:
type: string
description: 'Note: PHP callstack is only visible in dev/qa'
error:
type: string
enum:
- user_not_found
- not_authed
- invalid_auth
- account_inactiv
- no_permission
- invalid_arg_name
- invalid_array_arg
- invalid_charset
- invalid_form_data
- invalid_post_type
- missing_post_type
- team_added_to_org
- invalid_json
- json_not_object
- request_timeout
- upgrade_required
- fatal_error
ok:
$ref: '#/components/schemas/defs_ok_false'
additionalProperties: false
description: Schema for error response from reactions.list method
example:
error: invalid_auth
ok: false
security:
- slackAuth:
- reactions:read
summary: Slack Get Reactions List
x-api-evangelist-processing:
GenerateOperationSummariesFromPath: true
PascalCaseOperationSummaries: true
CaselCaseOperationIds: true
ChooseTags: true
x-microcks-operation:
delay: 0
dispatcher: FALLBACK
/reactions.remove:
post:
tags:
- Post
- Reactions
- Remove
description: Removes a reaction from an item.
externalDocs:
description: API method documentation
url: https://api.slack.com/methods/reactions.remove
operationId: postReactionsRemove
parameters:
- name: token
in: header
description: 'Authentication token. Requires scope: `reactions:write`'
required: true
schema:
type: string
requestBody:
content:
application/x-www-form-urlencoded:
schema:
required:
- name
type: object
properties:
name:
type: string
description: Reaction (emoji) name.
file:
type: string
description: File to remove reaction from.
file_comment:
type: string
description: File comment to remove reaction from.
channel:
type: string
description: >-
Channel where the message to remove reaction from was
posted.
timestamp:
type: string
description: Timestamp of the message to remove reaction from.
application/json:
schema:
required:
- name
type: object
properties:
name:
type: string
description: Reaction (emoji) name.
file:
type: string
description: File to remove reaction from.
file_comment:
type: string
description: File comment to remove reaction from.
channel:
type: string
description: >-
Channel where the message to remove reaction from was
posted.
timestamp:
type: string
description: Timestamp of the message to remove reaction from.
required: true
responses:
'200':
description: Typical success response
content:
application/json:
schema:
title: reactions.remove schema
required:
- ok
type: object
properties:
ok:
$ref: '#/components/schemas/defs_ok_true'
additionalProperties: false
description: Schema for successful response from reactions.remove method
example:
ok: true
default:
description: Typical error response
content:
application/json:
schema:
title: reactions.remove error schema
required:
- error
- ok
type: object
properties:
callstack:
type: string
description: 'Note: PHP callstack is only visible in dev/qa'
error:
type: string
enum:
- bad_timestamp
- file_not_found
- file_comment_not_found
- message_not_found
- no_item_specified
- invalid_name
- no_reaction
- not_authed
- invalid_auth
- account_inactive
- no_permission
- invalid_arg_name
- invalid_array_arg
- invalid_charset
- invalid_form_data
- invalid_post_type
- missing_post_type
- team_added_to_org
- invalid_json
- json_not_object
- request_timeout
- upgrade_required
- fatal_error
ok:
$ref: '#/components/schemas/defs_ok_false'
additionalProperties: false
description: Schema for error response from reactions.remove method
example:
error: no_reaction
ok: false
security:
- slackAuth:
- reactions:write
summary: Slack Post Reactions Remove
x-api-evangelist-processing:
GenerateOperationSummariesFromPath: true
PascalCaseOperationSummaries: true
CaselCaseOperationIds: true
ChooseTags: true
x-microcks-operation:
delay: 0
dispatcher: FALLBACK
components:
schemas: {}
tags:
- name: Add
- name: Get
- name: Lists
- name: Post
- name: Reactions
- name: Remove