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

# Classify text (Aboutness)

> **DEPRECATED:** This endpoint is deprecated and not recommended for new projects. It will not receive updates or support.

Classify arbitrary text to find relevant OpenAlex topics. Costs $0.01 per request.



## OpenAPI

````yaml /api-reference/openapi.json get /text/topics
openapi: 3.1.0
info:
  title: OpenAlex API
  description: >-
    The OpenAlex API provides access to a comprehensive catalog of scholarly
    works, authors, sources, institutions, topics, keywords, publishers, and
    funders. OpenAlex indexes over 250 million scholarly works.
  version: 1.0.0
  contact:
    name: OpenAlex Support
    email: support@openalex.org
    url: https://openalex.org
  license:
    name: CC0
    url: https://creativecommons.org/publicdomain/zero/1.0/
servers:
  - url: https://api.openalex.org
    description: OpenAlex Production API
security:
  - apiKey: []
tags:
  - name: Works
    description: Scholarly documents like journal articles, books, datasets, and theses
  - name: Authors
    description: People who create scholarly works
  - name: Sources
    description: Journals, repositories, and other venues where works are hosted
  - name: Institutions
    description: Universities, research organizations, and other affiliations
  - name: Topics
    description: Research topics automatically assigned to works
  - name: Keywords
    description: Short phrases identified from works' topics
  - name: Publishers
    description: Companies and organizations that publish scholarly works
  - name: Funders
    description: Organizations that fund research
  - name: Autocomplete
    description: Fast typeahead search for any entity type
  - name: Domains
    description: Top-level categories in the topic hierarchy (4 total)
  - name: Fields
    description: Second-level categories in the topic hierarchy (26 total)
  - name: Subfields
    description: Third-level categories in the topic hierarchy (254 total)
  - name: SDGs
    description: UN Sustainable Development Goals (17 total)
  - name: Countries
    description: Geographic countries for filtering research by location
  - name: Continents
    description: Geographic continents (7 total)
  - name: Languages
    description: Languages of scholarly works
  - name: Awards
    description: Research grants and funding awards
  - name: Concepts
    description: Legacy taxonomy of research areas (deprecated - use Topics instead)
  - name: Work Types
    description: Types of scholarly works (article, book, dataset, etc.)
  - name: Source Types
    description: Types of sources (journal, repository, conference, etc.)
  - name: Institution Types
    description: Types of institutions (education, healthcare, company, etc.)
  - name: Licenses
    description: Open access licenses (CC BY, CC BY-SA, etc.)
paths:
  /text/topics:
    get:
      tags:
        - Topics
      summary: Classify text (Aboutness)
      description: >-
        **DEPRECATED:** This endpoint is deprecated and not recommended for new
        projects. It will not receive updates or support.


        Classify arbitrary text to find relevant OpenAlex topics. Costs $0.01
        per request.
      operationId: classifyText
      parameters:
        - name: title
          in: query
          description: Title text to classify
          schema:
            type: string
        - name: abstract
          in: query
          description: Abstract text to classify
          schema:
            type: string
        - $ref: '#/components/parameters/api_key'
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TextClassificationResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '429':
          $ref: '#/components/responses/RateLimited'
      deprecated: true
components:
  parameters:
    api_key:
      name: api_key
      in: query
      description: >-
        Your OpenAlex API key (required). Get a free key at
        https://openalex.org/settings/api
      required: true
      schema:
        type: string
  schemas:
    TextClassificationResponse:
      type: object
      properties:
        meta:
          type: object
          properties:
            count:
              type: integer
        results:
          type: array
          items:
            $ref: '#/components/schemas/WorkTopic'
    WorkTopic:
      type: object
      properties:
        id:
          type: string
        display_name:
          type: string
        score:
          type: number
        subfield:
          type: object
          properties:
            id:
              type: string
            display_name:
              type: string
          description: The parent [subfield](/api-reference/subfields)
        field:
          type: object
          properties:
            id:
              type: string
            display_name:
              type: string
          description: The parent [field](/api-reference/fields)
        domain:
          type: object
          properties:
            id:
              type: string
            display_name:
              type: string
          description: The parent [domain](/api-reference/domains)
    Error:
      type: object
      properties:
        error:
          type: string
          description: Error type
        message:
          type: string
          description: Human-readable error message
  responses:
    BadRequest:
      description: Bad request - invalid parameters
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    RateLimited:
      description: Rate limit exceeded
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  securitySchemes:
    apiKey:
      type: apiKey
      in: query
      name: api_key
      description: >-
        Your OpenAlex API key. Get a free key at
        https://openalex.org/settings/api

````