> ## Documentation Index
> Fetch the complete documentation index at: https://developer.folk.app/llms.txt
> Use this file to discover all available pages before exploring further.

# (Beta) List the variables of a campaign

> Retrieve a paginated list of the `{{variables}}` a campaign's subjects and bodies can use: the fields of its people or companies, the text and numeric custom fields of its group, `{{unsubscribeLink}}` and `{{signature}}`. Write each `token` as given. A variable without a value for a recipient is removed from their message. `{{signature}}` inserts the sender's signature on a new step or message, as listed by `GET /v1/message-senders`: end a body with `<p>{{signature}}</p>` to sign it, rather than writing the signature yourself.<br/><Warning>This endpoint is currently in open beta. The API surface may change as we iterate based on feedback.</Warning>



## OpenAPI

````yaml /schemas/2025-06-09.json get /v1/campaigns/{campaignId}/variables
openapi: 3.1.0
info:
  title: Folk External API
  description: >-
    Folk's public REST API lets you manage workspaces, groups, contacts, and
    real-time triggers.
  version: '2025-06-09'
  contact:
    name: folk
    email: tech@folk.app
    url: https://folk.app
servers:
  - url: https://api.folk.app
    description: Folk's public API production base URL.
    x-internal: false
security: []
tags:
  - name: Campaigns
    description: >-
      Operations related to campaigns: emails, or sequences of emails, sent to
      people or companies, and their messages.
  - name: Companies
    description: Operations related to companies.
  - name: Credits
    description: Operations related to credits.
  - name: Custom objects
    description: >-
      Operations related to objects of any type in a group, such as deals. Every
      object type shares these endpoints, with its name given as the
      `objectType` path parameter.
  - name: Groups
    description: Operations related to groups.
  - name: Group members
    description: Operations related to group members.
  - name: Group custom fields
    description: Operations related to group custom fields.
  - name: Interactions
    description: Operations related to interactions.
  - name: Notes
    description: Operations related to notes.
  - name: People
    description: Operations related to people.
  - name: Person enrichments
    description: Operations related to person enrichments.
  - name: Reminders
    description: Operations related to reminders.
  - name: Tasks
    description: Operations related to tasks.
  - name: Users
    description: Operations related to users.
  - name: Views
    description: Operations related to views.
  - name: Webhooks
    description: Operations related to webhooks.
paths:
  /v1/campaigns/{campaignId}/variables:
    get:
      tags:
        - Campaigns
      summary: List the variables of a campaign
      description: >-
        Retrieve a paginated list of the `{{variables}}` a campaign's subjects
        and bodies can use: the fields of its people or companies, the text and
        numeric custom fields of its group, `{{unsubscribeLink}}` and
        `{{signature}}`. Write each `token` as given. A variable without a value
        for a recipient is removed from their message. `{{signature}}` inserts
        the sender's signature on a new step or message, as listed by `GET
        /v1/message-senders`: end a body with `<p>{{signature}}</p>` to sign it,
        rather than writing the signature yourself.<br/><Warning>This endpoint
        is currently in open beta. The API surface may change as we iterate
        based on feedback.</Warning>
      operationId: listCampaignVariables
      parameters:
        - schema:
            type: string
            minLength: 40
            maxLength: 40
          required: true
          description: The ID of the campaign.
          name: campaignId
          in: path
        - schema:
            type: integer
            minimum: 1
            maximum: 100
            default: 20
          required: false
          description: The number of items to return.
          example: 20
          name: limit
          in: query
        - schema:
            type: string
            maxLength: 512
          required: false
          description: >-
            A cursor for pagination across multiple pages of results. Don’t
            include this parameter on the first call. Use the
            `pagination.nextLink` value returned in a previous response to
            request subsequent results.
          example: eyJvZmZzZXQiOjN9
          name: cursor
          in: query
      responses:
        '200':
          description: A page of the variables the campaign can use.
          headers:
            X-RateLimit-Limit:
              $ref: '#/components/headers/X-RateLimit-Limit'
            X-RateLimit-Remaining:
              $ref: '#/components/headers/X-RateLimit-Remaining'
            X-RateLimit-Reset:
              $ref: '#/components/headers/X-RateLimit-Reset'
            X-RateLimit-Limit-Burst:
              $ref: '#/components/headers/X-RateLimit-Limit-Burst'
            X-RateLimit-Remaining-Burst:
              $ref: '#/components/headers/X-RateLimit-Remaining-Burst'
            X-RateLimit-Reset-Burst:
              $ref: '#/components/headers/X-RateLimit-Reset-Burst'
            RateLimit-Policy:
              $ref: '#/components/headers/RateLimit-Policy'
            RateLimit:
              $ref: '#/components/headers/RateLimit'
            Retry-After:
              $ref: '#/components/headers/Retry-After'
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    type: object
                    properties:
                      items:
                        type: array
                        items:
                          $ref: '#/components/schemas/CampaignVariable'
                      pagination:
                        type: object
                        properties:
                          nextLink:
                            type: string
                    required:
                      - items
                      - pagination
                    example:
                      items:
                        - token: >-
                            {{customFieldValues.grp_bc984b3f-0386-434d-82d7-a91eb6badd71.Deal
                            stage}}
                          key: >-
                            customFieldValues.grp_bc984b3f-0386-434d-82d7-a91eb6badd71.Deal
                            stage
                          label: Deal stage
                          source: customField
                          type: text
                          group:
                            id: grp_bc984b3f-0386-434d-82d7-a91eb6badd71
                            name: Leads
                      pagination:
                        nextLink: >-
                          https://api.folk.app/v1/campaigns/cmp_9b2f1c1e-2b8a-4d1e-8f5a-3c2d1e0f9a8b/variables?limit=20&cursor=eyJvZmZzZXQiOjIwfQ%3D%3D
                  deprecations:
                    type: array
                    items:
                      type: string
                    example:
                      - This field is deprecated
                required:
                  - data
              example:
                data:
                  items:
                    - token: >-
                        {{customFieldValues.grp_bc984b3f-0386-434d-82d7-a91eb6badd71.Deal
                        stage}}
                      key: >-
                        customFieldValues.grp_bc984b3f-0386-434d-82d7-a91eb6badd71.Deal
                        stage
                      label: Deal stage
                      source: customField
                      type: text
                      group:
                        id: grp_bc984b3f-0386-434d-82d7-a91eb6badd71
                        name: Leads
                  pagination:
                    nextLink: >-
                      https://api.folk.app/v1/campaigns/cmp_9b2f1c1e-2b8a-4d1e-8f5a-3c2d1e0f9a8b/variables?limit=20&cursor=eyJvZmZzZXQiOjIwfQ%3D%3D
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
        '404':
          $ref: '#/components/responses/NotFound'
        '422':
          $ref: '#/components/responses/UnprocessableEntity'
        '429':
          $ref: '#/components/responses/TooManyRequests'
        '500':
          $ref: '#/components/responses/InternalServerError'
        '503':
          $ref: '#/components/responses/ServiceUnavailable'
      security:
        - bearerApiKeyAuth: []
components:
  headers:
    X-RateLimit-Limit:
      schema:
        type: integer
        example: 1000
      description: >-
        The maximum number of requests that you can make in the current rate
        limit window.
    X-RateLimit-Remaining:
      schema:
        type: integer
        example: 998
      description: The number of requests remaining in the current rate limit window.
    X-RateLimit-Reset:
      schema:
        type: integer
        example: 1747322958
      description: >-
        The time at which the current rate limit window resets, in UTC epoch
        seconds.
    X-RateLimit-Limit-Burst:
      schema:
        type: integer
        example: 20
      description: >-
        The maximum number of requests that you can make in the current burst
        rate limit window.
    X-RateLimit-Remaining-Burst:
      schema:
        type: integer
        example: 18
      description: The number of requests remaining in the current burst rate limit window.
    X-RateLimit-Reset-Burst:
      schema:
        type: integer
        example: 1747322902
      description: >-
        The time at which the current burst rate limit window resets, in UTC
        epoch seconds.
    RateLimit-Policy:
      schema:
        type: string
        example: '"default";q=600;w=60, "burst";q=20;w=2'
      description: >-
        The rate limit policies applied to the request, as defined by the IETF
        RateLimit header fields draft. `q` is the number of requests allowed per
        window and `w` the window length in seconds.
    RateLimit:
      schema:
        type: string
        example: '"default";r=598;t=42, "burst";r=18;t=1'
      description: >-
        The current usage of each rate limit policy, as defined by the IETF
        RateLimit header fields draft. `r` is the number of requests remaining
        and `t` the number of seconds until the window resets.
    Retry-After:
      schema:
        type: integer
        example: 60
      description: >-
        The number of seconds to wait before making a new request after hitting
        the rate limit.
  schemas:
    CampaignVariable:
      type: object
      properties:
        token:
          type: string
          description: >-
            The exact text to write in a subject or body, with `\`, `|`, `}` and
            leading or trailing whitespace of a custom field name escaped by a
            backslash.
          example: '{{firstName}}'
        key:
          type: string
          description: >-
            The path of the value in the person or company, unescaped. A custom
            field is addressed by its group and its name.
          example: firstName
        label:
          type: string
          description: The name of the variable in the app.
          example: First name
        source:
          type: string
          enum:
            - native
            - customField
            - unsubscribeLink
            - signature
          description: >-
            Where the value comes from. `native`: a field of the person or
            company. `customField`: a custom field of the campaign group.
            `unsubscribeLink`: only valid as the whole `href` of a link in a
            body, `<a href="{{unsubscribeLink}}">`, with a `custom_domain`
            sender. `signature`: the step's signature, only valid alone in the
            last paragraph of a body, `<p>{{signature}}</p>`; it inserts the
            sender's signature on a new step or message.
          example: native
        type:
          type: string
          enum:
            - text
            - numeric
            - date
            - url
          description: >-
            The type of the value. For a field holding several values, the
            variable takes the first one.
          example: text
        group:
          type: object
          properties:
            id:
              type: string
              description: The ID of the group of the custom field.
              example: grp_bc984b3f-0386-434d-82d7-a91eb6badd71
            name:
              type: string
              description: The name of the group of the custom field.
              example: Leads
          required:
            - id
            - name
          description: The group of a `customField` variable.
      required:
        - token
        - key
        - label
        - source
        - type
      example:
        token: >-
          {{customFieldValues.grp_bc984b3f-0386-434d-82d7-a91eb6badd71.Deal
          stage}}
        key: customFieldValues.grp_bc984b3f-0386-434d-82d7-a91eb6badd71.Deal stage
        label: Deal stage
        source: customField
        type: text
        group:
          id: grp_bc984b3f-0386-434d-82d7-a91eb6badd71
          name: Leads
    Error:
      type: object
      properties:
        error:
          type: object
          properties:
            code:
              type: string
              example: TOO_MANY_REQUESTS
            message:
              type: string
              example: You have exceeded your rate limit.
            documentationUrl:
              type: string
              format: uri
              example: https://developer.folk.app/api-reference/errors#rate-limiting
            requestId:
              type: string
              format: uuid
              example: 123e4567-e89b-12d3-a456-426614174000
            timestamp:
              type: string
              format: date-time
              example: '2025-10-01T12:00:00Z'
            details:
              type: object
              additionalProperties: true
              example:
                policy: burst
                limit: 20
                remaining: 0
                windowSeconds: 2
                retryAfter: '2025-10-01T12:00:02.000Z'
          required:
            - code
            - message
            - documentationUrl
            - requestId
            - timestamp
      required:
        - error
      description: Error response containing error details.
    RateLimitError:
      type: object
      properties:
        error:
          type: object
          properties:
            code:
              type: string
              example: TOO_MANY_REQUESTS
            message:
              type: string
              example: You have exceeded your rate limit.
            documentationUrl:
              type: string
              format: uri
              example: https://developer.folk.app/api-reference/errors#rate-limiting
            requestId:
              type: string
              format: uuid
              example: 123e4567-e89b-12d3-a456-426614174000
            timestamp:
              type: string
              format: date-time
              example: '2025-10-01T12:00:00Z'
            details:
              type: object
              properties:
                policy:
                  type: string
                  enum:
                    - default
                    - burst
                  description: The name of the rate limit policy.
                limit:
                  type: integer
                  description: The maximum number of requests allowed per window.
                remaining:
                  type: integer
                  description: The number of requests remaining in the current window.
                windowSeconds:
                  type: integer
                  description: The length of the window, in seconds.
                retryAfter:
                  type: string
                  format: date-time
                  description: When the current window resets.
                policies:
                  type: array
                  items:
                    type: object
                    properties:
                      policy:
                        type: string
                        enum:
                          - default
                          - burst
                        description: The name of the rate limit policy.
                      limit:
                        type: integer
                        description: The maximum number of requests allowed per window.
                      remaining:
                        type: integer
                        description: >-
                          The number of requests remaining in the current
                          window.
                      windowSeconds:
                        type: integer
                        description: The length of the window, in seconds.
                      retryAfter:
                        type: string
                        format: date-time
                        description: When the current window resets.
                    required:
                      - policy
                      - limit
                      - remaining
                      - windowSeconds
                      - retryAfter
                  description: >-
                    The status of every rate limit policy applied to the
                    request.
              required:
                - policy
                - limit
                - remaining
                - windowSeconds
                - retryAfter
                - policies
              description: >-
                The exceeded rate limit policy. When several are exceeded, the
                one resetting last.
          required:
            - code
            - message
            - documentationUrl
            - requestId
            - timestamp
            - details
      required:
        - error
      description: Error response returned when a rate limit is exceeded.
  responses:
    BadRequest:
      description: The request was unacceptable, often due to missing an invalid parameter.
      headers:
        X-RateLimit-Limit:
          $ref: '#/components/headers/X-RateLimit-Limit'
        X-RateLimit-Remaining:
          $ref: '#/components/headers/X-RateLimit-Remaining'
        X-RateLimit-Reset:
          $ref: '#/components/headers/X-RateLimit-Reset'
        X-RateLimit-Limit-Burst:
          $ref: '#/components/headers/X-RateLimit-Limit-Burst'
        X-RateLimit-Remaining-Burst:
          $ref: '#/components/headers/X-RateLimit-Remaining-Burst'
        X-RateLimit-Reset-Burst:
          $ref: '#/components/headers/X-RateLimit-Reset-Burst'
        RateLimit-Policy:
          $ref: '#/components/headers/RateLimit-Policy'
        RateLimit:
          $ref: '#/components/headers/RateLimit'
        Retry-After:
          $ref: '#/components/headers/Retry-After'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              code: INVALID_REQUEST
              message: The request was invalid.
              documentationUrl: https://developer.folk.app/api-reference/errors#bad-request
              requestId: 123e4567-e89b-12d3-a456-426614174000
              timestamp: '2025-10-01T12:00:00Z'
    Unauthorized:
      description: No valid API key provided.
      headers:
        X-RateLimit-Limit:
          $ref: '#/components/headers/X-RateLimit-Limit'
        X-RateLimit-Remaining:
          $ref: '#/components/headers/X-RateLimit-Remaining'
        X-RateLimit-Reset:
          $ref: '#/components/headers/X-RateLimit-Reset'
        X-RateLimit-Limit-Burst:
          $ref: '#/components/headers/X-RateLimit-Limit-Burst'
        X-RateLimit-Remaining-Burst:
          $ref: '#/components/headers/X-RateLimit-Remaining-Burst'
        X-RateLimit-Reset-Burst:
          $ref: '#/components/headers/X-RateLimit-Reset-Burst'
        RateLimit-Policy:
          $ref: '#/components/headers/RateLimit-Policy'
        RateLimit:
          $ref: '#/components/headers/RateLimit'
        Retry-After:
          $ref: '#/components/headers/Retry-After'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              code: UNAUTHORIZED
              message: No valid API key provided.
              documentationUrl: https://developer.folk.app/api-reference/errors#unauthorized
              requestId: 123e4567-e89b-12d3-a456-426614174000
              timestamp: '2025-10-01T12:00:00Z'
    Forbidden:
      description: The API key doesn’t have permissions to perform the request.
      headers:
        X-RateLimit-Limit:
          $ref: '#/components/headers/X-RateLimit-Limit'
        X-RateLimit-Remaining:
          $ref: '#/components/headers/X-RateLimit-Remaining'
        X-RateLimit-Reset:
          $ref: '#/components/headers/X-RateLimit-Reset'
        X-RateLimit-Limit-Burst:
          $ref: '#/components/headers/X-RateLimit-Limit-Burst'
        X-RateLimit-Remaining-Burst:
          $ref: '#/components/headers/X-RateLimit-Remaining-Burst'
        X-RateLimit-Reset-Burst:
          $ref: '#/components/headers/X-RateLimit-Reset-Burst'
        RateLimit-Policy:
          $ref: '#/components/headers/RateLimit-Policy'
        RateLimit:
          $ref: '#/components/headers/RateLimit'
        Retry-After:
          $ref: '#/components/headers/Retry-After'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              code: FORBIDDEN
              message: The API key doesn’t have permissions to perform the request.
              documentationUrl: https://developer.folk.app/api-reference/errors#forbidden
              requestId: 123e4567-e89b-12d3-a456-426614174000
              timestamp: '2025-10-01T12:00:00Z'
    NotFound:
      description: The requested resource doesn’t exist.
      headers:
        X-RateLimit-Limit:
          $ref: '#/components/headers/X-RateLimit-Limit'
        X-RateLimit-Remaining:
          $ref: '#/components/headers/X-RateLimit-Remaining'
        X-RateLimit-Reset:
          $ref: '#/components/headers/X-RateLimit-Reset'
        X-RateLimit-Limit-Burst:
          $ref: '#/components/headers/X-RateLimit-Limit-Burst'
        X-RateLimit-Remaining-Burst:
          $ref: '#/components/headers/X-RateLimit-Remaining-Burst'
        X-RateLimit-Reset-Burst:
          $ref: '#/components/headers/X-RateLimit-Reset-Burst'
        RateLimit-Policy:
          $ref: '#/components/headers/RateLimit-Policy'
        RateLimit:
          $ref: '#/components/headers/RateLimit'
        Retry-After:
          $ref: '#/components/headers/Retry-After'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              code: RESOURCE_NOT_FOUND
              message: The requested resource was not found.
              documentationUrl: https://developer.folk.app/api-reference/errors#not-found
              requestId: 123e4567-e89b-12d3-a456-426614174000
              timestamp: '2025-10-01T12:00:00Z'
    UnprocessableEntity:
      description: >-
        The request was unacceptable, often due to missing or invalid
        parameters.
      headers:
        X-RateLimit-Limit:
          $ref: '#/components/headers/X-RateLimit-Limit'
        X-RateLimit-Remaining:
          $ref: '#/components/headers/X-RateLimit-Remaining'
        X-RateLimit-Reset:
          $ref: '#/components/headers/X-RateLimit-Reset'
        X-RateLimit-Limit-Burst:
          $ref: '#/components/headers/X-RateLimit-Limit-Burst'
        X-RateLimit-Remaining-Burst:
          $ref: '#/components/headers/X-RateLimit-Remaining-Burst'
        X-RateLimit-Reset-Burst:
          $ref: '#/components/headers/X-RateLimit-Reset-Burst'
        RateLimit-Policy:
          $ref: '#/components/headers/RateLimit-Policy'
        RateLimit:
          $ref: '#/components/headers/RateLimit'
        Retry-After:
          $ref: '#/components/headers/Retry-After'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              code: UNPROCESSABLE_ENTITY
              message: Invalid query parameters
              documentationUrl: >-
                https://developer.folk.app/api-reference/errors#unprocessable-entity
              details:
                issues:
                  - code: too_small
                    minimum: 1
                    type: number
                    inclusive: true
                    exact: false
                    message: Number must be greater than or equal to 1
                    path:
                      - limit
              requestId: 123e4567-e89b-12d3-a456-426614174000
              timestamp: '2025-10-01T12:00:00Z'
    TooManyRequests:
      description: >-
        Too many requests hit the API too quickly. We recommend an exponential
        backoff of your requests.
      headers:
        X-RateLimit-Limit:
          $ref: '#/components/headers/X-RateLimit-Limit'
        X-RateLimit-Remaining:
          $ref: '#/components/headers/X-RateLimit-Remaining'
        X-RateLimit-Reset:
          $ref: '#/components/headers/X-RateLimit-Reset'
        X-RateLimit-Limit-Burst:
          $ref: '#/components/headers/X-RateLimit-Limit-Burst'
        X-RateLimit-Remaining-Burst:
          $ref: '#/components/headers/X-RateLimit-Remaining-Burst'
        X-RateLimit-Reset-Burst:
          $ref: '#/components/headers/X-RateLimit-Reset-Burst'
        RateLimit-Policy:
          $ref: '#/components/headers/RateLimit-Policy'
        RateLimit:
          $ref: '#/components/headers/RateLimit'
        Retry-After:
          $ref: '#/components/headers/Retry-After'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/RateLimitError'
          example:
            error:
              code: TOO_MANY_REQUESTS
              message: You have exceeded your rate limit.
              documentationUrl: https://developer.folk.app/api-reference/errors#rate-limiting
              requestId: 123e4567-e89b-12d3-a456-426614174000
              timestamp: '2025-10-01T12:00:00Z'
              details:
                policy: burst
                limit: 20
                remaining: 0
                windowSeconds: 2
                retryAfter: '2025-10-01T12:00:02.000Z'
                policies:
                  - policy: default
                    limit: 600
                    remaining: 412
                    windowSeconds: 60
                    retryAfter: '2025-10-01T12:01:00.000Z'
                  - policy: burst
                    limit: 20
                    remaining: 0
                    windowSeconds: 2
                    retryAfter: '2025-10-01T12:00:02.000Z'
    InternalServerError:
      description: Something went wrong on our end.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              code: INTERNAL_SERVER_ERROR
              message: An internal server error occurred.
              documentationUrl: >-
                https://developer.folk.app/api-reference/errors#internal-server-error
              requestId: 123e4567-e89b-12d3-a456-426614174000
              timestamp: '2025-10-01T12:00:00Z'
    ServiceUnavailable:
      description: The server is overloaded or down for maintenance.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              code: SERVICE_UNAVAILABLE
              message: The service is currently unavailable.
              documentationUrl: >-
                https://developer.folk.app/api-reference/errors#service-unavailable
              requestId: 123e4567-e89b-12d3-a456-426614174000
              timestamp: '2025-10-01T12:00:00Z'
  securitySchemes:
    bearerApiKeyAuth:
      type: http
      scheme: bearer
      description: API key for authentication

````

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