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

# List topics

> Returns the hierarchical topic taxonomy. Use parent_id to navigate the tree.



## OpenAPI

````yaml /openapi.json get /v1/topics
openapi: 3.1.0
info:
  description: Public API for Particle — news intelligence, financial data, and analysis.
  title: Particle API
  version: 0.1.0
servers:
  - url: https://api.particle.pro
security:
  - ApiKeyHeader: []
  - BearerAuth: []
paths:
  /v1/topics:
    get:
      tags:
        - Topics
        - tier:standard
      summary: List topics
      description: >-
        Returns the hierarchical topic taxonomy. Use parent_id to navigate the
        tree.
      operationId: list-topics
      parameters:
        - description: Results per page
          explode: false
          in: query
          name: limit
          schema:
            default: 25
            description: Results per page
            format: int64
            maximum: 100
            minimum: 1
            type: integer
        - description: Opaque pagination cursor from previous response
          explode: false
          in: query
          name: cursor
          schema:
            description: Opaque pagination cursor from previous response
            type: string
        - description: >-
            Get children of this topic. Accepts topic ID, ancestry slug, or
            ancestry path hash. Omit for top-level roots.
          explode: false
          in: query
          name: parent_id
          schema:
            description: >-
              Get children of this topic. Accepts topic ID, ancestry slug, or
              ancestry path hash. Omit for top-level roots.
            type: string
        - description: Filter by exact ancestry path hash.
          explode: false
          in: query
          name: ancestry_path
          schema:
            description: Filter by exact ancestry path hash.
            maxLength: 50
            type: string
        - description: Filter by ancestry path prefix (all descendants).
          explode: false
          in: query
          name: ancestry_path_prefix
          schema:
            description: Filter by ancestry path prefix (all descendants).
            maxLength: 50
            type: string
      responses:
        '200':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PageTopic'
          description: OK
        default:
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/PlatformError'
          description: Error
      x-codeSamples:
        - label: cURL
          lang: curl
          source: |-
            curl -H "X-API-Key: $PARTICLE_API_KEY" \
              "https://api.particle.pro/v1/topics?limit=25"
components:
  schemas:
    PageTopic:
      additionalProperties: false
      properties:
        cursor:
          description: Pass to next request for more results
          type: string
        data:
          description: List of results
          items:
            $ref: '#/components/schemas/Topic'
          type:
            - array
            - 'null'
        has_more:
          description: Whether more results exist
          type: boolean
      required:
        - data
        - has_more
      type: object
    PlatformError:
      additionalProperties: false
      properties:
        detail:
          description: >-
            A human-readable explanation specific to this occurrence of the
            problem.
          examples:
            - Property foo is required but is missing.
          type: string
        error_code:
          type: string
        errors:
          description: Optional list of individual error details
          items:
            $ref: '#/components/schemas/ErrorDetail'
          type:
            - array
            - 'null'
        instance:
          description: >-
            A URI reference that identifies the specific occurrence of the
            problem.
          examples:
            - https://example.com/error-log/abc123
          format: uri
          type: string
        resolve:
          $ref: '#/components/schemas/ErrorResolve'
        status:
          description: HTTP status code
          examples:
            - 400
          format: int64
          type: integer
        title:
          description: >-
            A short, human-readable summary of the problem type. This value
            should not change between occurrences of the error.
          examples:
            - Bad Request
          type: string
        type:
          default: about:blank
          description: A URI reference to human-readable documentation for the error.
          examples:
            - https://example.com/errors/example
          format: uri
          type: string
      type: object
    Topic:
      additionalProperties: false
      properties:
        ancestry:
          description: Human-readable breadcrumb path (e.g. Business > Technology > AI)
          type: string
        ancestry_path:
          description: Hash-based ancestry path for programmatic filtering
          type: string
        episode_count:
          description: >-
            Number of episodes in this podcast that cover this topic (only
            populated for /v1/podcasts/{id} topic lists)
          format: int64
          type: integer
        id:
          description: Unique identifier
          type: string
        name:
          description: Topic name
          type: string
        slug:
          description: >-
            Ancestry-based slug (e.g., technology/artificial-intelligence). Can
            be used as topic_id.
          type: string
      required:
        - id
        - name
        - slug
      type: object
    ErrorDetail:
      additionalProperties: false
      properties:
        location:
          description: >-
            Where the error occurred, e.g. 'body.items[3].tags' or
            'path.thing-id'
          type: string
        message:
          description: Error message text
          type: string
        value:
          description: The value at the given location
      type: object
    ErrorResolve:
      additionalProperties: false
      properties:
        action:
          type: string
        endpoint:
          type: string
        message:
          type: string
        method:
          type: string
        url:
          type: string
      required:
        - message
      type: object
  securitySchemes:
    ApiKeyHeader:
      description: Pass your API key in the X-API-Key header (recommended).
      in: header
      name: X-API-Key
      type: apiKey
    BearerAuth:
      description: Pass your API key as a Bearer token in the Authorization header.
      scheme: bearer
      type: http

````