ChEMBL Target API

openapi: 3.0.3
info:
  title: ChEMBL Data REST Activity Target API
  description: ChEMBL is a manually curated database of bioactive molecules with drug-like properties, maintained by the EMBL-EBI. This REST API provides programmatic access to bioactive molecules, drug targets, bioactivity measurements, approved drugs, assay data, and clinical trial compound information. ChEMBL_37 contains over 2.9 million distinct compounds, 24.5 million activities, and 18,552 targets.
  version: ChEMBL_37
  contact:
    name: ChEMBL Team
    email: chembl-help@ebi.ac.uk
    url: https://www.ebi.ac.uk/chembl/
  license:
    name: Creative Commons Attribution-ShareAlike 3.0 Unported
    url: https://creativecommons.org/licenses/by-sa/3.0/
  termsOfService: https://www.ebi.ac.uk/about/terms-of-use/
  x-logo:
    url: https://www.ebi.ac.uk/chembl/static/chembl/img/chembl_logo.png
servers:
- url: https://www.ebi.ac.uk/chembl/api/data
  description: ChEMBL Production API Server
tags:
- name: Target
  description: Protein and non-protein targets defined in assays.
paths:
  /target:
    get:
      tags:
      - Target
      summary: List targets
      description: Retrieve a paginated list of targets. Targets can be single proteins, protein complexes, organisms, cell lines, or other biological entities.
      operationId: listTargets
      parameters:
      - $ref: '#/components/parameters/format'
      - $ref: '#/components/parameters/limit'
      - $ref: '#/components/parameters/offset'
      - name: target_chembl_id
        in: query
        description: Filter by target ChEMBL ID
        schema:
          type: string
          example: CHEMBL301
      - name: target_type
        in: query
        description: Filter by target type (e.g., SINGLE PROTEIN, PROTEIN COMPLEX)
        schema:
          type: string
          example: SINGLE PROTEIN
      - name: organism
        in: query
        description: Filter by organism (e.g., Homo sapiens)
        schema:
          type: string
          example: Homo sapiens
      - name: pref_name
        in: query
        description: Filter by preferred target name
        schema:
          type: string
      responses:
        '200':
          description: Paginated list of targets
          content:
            application/json:
              schema:
                type: object
                properties:
                  meta:
                    $ref: '#/components/schemas/Meta'
                  targets:
                    type: array
                    items:
                      $ref: '#/components/schemas/Target'
        '400':
          $ref: '#/components/responses/BadRequest'
        '404':
          $ref: '#/components/responses/NotFound'
  /target/{target_chembl_id}:
    get:
      tags:
      - Target
      summary: Get target by ChEMBL ID
      description: Retrieve a single target record by its ChEMBL ID.
      operationId: getTarget
      parameters:
      - name: target_chembl_id
        in: path
        required: true
        description: ChEMBL ID of the target
        schema:
          type: string
          example: CHEMBL301
      - $ref: '#/components/parameters/format'
      responses:
        '200':
          description: Target record
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Target'
        '404':
          $ref: '#/components/responses/NotFound'
  /target/search:
    get:
      tags:
      - Target
      summary: Search targets
      description: Full-text search for targets by name or other text fields.
      operationId: searchTargets
      parameters:
      - name: q
        in: query
        required: true
        description: Search query string
        schema:
          type: string
          example: kinase
      - $ref: '#/components/parameters/format'
      - $ref: '#/components/parameters/limit'
      - $ref: '#/components/parameters/offset'
      responses:
        '200':
          description: Search results
          content:
            application/json:
              schema:
                type: object
                properties:
                  meta:
                    $ref: '#/components/schemas/Meta'
                  targets:
                    type: array
                    items:
                      $ref: '#/components/schemas/Target'
  /go_slim:
    get:
      tags:
      - Target
      summary: List GO slim classifications
      description: Retrieve gene ontology slim classifications used to annotate targets.
      operationId: listGoSlim
      parameters:
      - $ref: '#/components/parameters/format'
      - $ref: '#/components/parameters/limit'
      - $ref: '#/components/parameters/offset'
      responses:
        '200':
          description: Paginated list of GO slim entries
          content:
            application/json:
              schema:
                type: object
                properties:
                  meta:
                    $ref: '#/components/schemas/Meta'
                  go_slims:
                    type: array
                    items:
                      $ref: '#/components/schemas/GoSlim'
  /protein_class:
    get:
      tags:
      - Target
      summary: List protein classifications
      description: Retrieve hierarchical protein family classification information for targets.
      operationId: listProteinClasses
      parameters:
      - $ref: '#/components/parameters/format'
      - $ref: '#/components/parameters/limit'
      - $ref: '#/components/parameters/offset'
      responses:
        '200':
          description: Paginated list of protein classifications
          content:
            application/json:
              schema:
                type: object
                properties:
                  meta:
                    $ref: '#/components/schemas/Meta'
                  protein_classifications:
                    type: array
                    items:
                      $ref: '#/components/schemas/ProteinClass'
  /tissue:
    get:
      tags:
      - Target
      summary: List tissues
      description: Retrieve tissue classification information.
      operationId: listTissues
      parameters:
      - $ref: '#/components/parameters/format'
      - $ref: '#/components/parameters/limit'
      - $ref: '#/components/parameters/offset'
      - name: pref_name
        in: query
        description: Filter by tissue preferred name
        schema:
          type: string
      responses:
        '200':
          description: Paginated list of tissues
          content:
            application/json:
              schema:
                type: object
                properties:
                  meta:
                    $ref: '#/components/schemas/Meta'
                  tissues:
                    type: array
                    items:
                      $ref: '#/components/schemas/Tissue'
components:
  parameters:
    offset:
      name: offset
      in: query
      description: Number of records to skip for pagination
      schema:
        type: integer
        default: 0
        minimum: 0
    format:
      name: format
      in: query
      description: Response format
      schema:
        type: string
        enum:
        - json
        - xml
        - yaml
        - jsonp
        default: json
    limit:
      name: limit
      in: query
      description: Number of records to return per page (default 20, max 1000)
      schema:
        type: integer
        default: 20
        maximum: 1000
        minimum: 1
  schemas:
    Error:
      type: object
      properties:
        error_message:
          type: string
        status:
          type: string
    Meta:
      type: object
      description: Pagination metadata for list responses
      properties:
        limit:
          type: integer
          description: Number of records returned per page
        next:
          type: string
          nullable: true
          description: URL for the next page of results
        offset:
          type: integer
          description: Number of records skipped
        previous:
          type: string
          nullable: true
          description: URL for the previous page of results
        total_count:
          type: integer
          description: Total number of records matching the query
    Tissue:
      type: object
      description: Tissue classification used in ChEMBL
      properties:
        tissue_chembl_id:
          type: string
          description: ChEMBL ID of the tissue
        bto_id:
          type: string
          nullable: true
          description: BRENDA Tissue Ontology identifier
        caloha_id:
          type: string
          nullable: true
        efo_id:
          type: string
          nullable: true
        pref_name:
          type: string
          description: Preferred tissue name
        uberon_id:
          type: string
          nullable: true
          description: UBERON ontology identifier
    GoSlim:
      type: object
      description: Gene Ontology slim term for target classification
      properties:
        go_id:
          type: string
          description: Gene Ontology term ID
        protein_class_desc:
          type: string
          nullable: true
        parent_go_id:
          type: string
          nullable: true
        prot_class_id:
          type: integer
    Target:
      type: object
      description: A biological target in ChEMBL
      properties:
        target_chembl_id:
          type: string
          description: Unique ChEMBL ID for the target
          example: CHEMBL301
        pref_name:
          type: string
          description: Preferred target name
        target_type:
          type: string
          description: Target type (e.g., SINGLE PROTEIN, PROTEIN COMPLEX, ORGANISM, CELL-LINE)
        organism:
          type: string
          nullable: true
          description: Source organism of the target
        tax_id:
          type: integer
          nullable: true
          description: NCBI taxonomy ID of the target organism
        species_group_flag:
          type: boolean
          nullable: true
          description: Indicates target represents a group of species
        score:
          type: number
          nullable: true
          description: Relevance score for search results
        target_components:
          type: array
          items:
            $ref: '#/components/schemas/TargetComponent'
          description: Protein components making up this target
        cross_references:
          type: array
          items:
            type: object
            properties:
              xref_id:
                type: string
              xref_name:
                type: string
              xref_src:
                type: string
          description: Cross-references to external databases (UniProt, Ensembl, etc.)
    ProteinClass:
      type: object
      description: Protein family classification in the hierarchy
      properties:
        prot_class_id:
          type: integer
        class_level:
          type: integer
          description: Hierarchy level (0=root)
        l1:
          type: string
          nullable: true
          description: Level 1 classification
        l2:
          type: string
          nullable: true
          description: Level 2 classification
        l3:
          type: string
          nullable: true
          description: Level 3 classification
        l4:
          type: string
          nullable: true
          description: Level 4 classification
        l5:
          type: string
          nullable: true
          description: Level 5 classification
        l6:
          type: string
          nullable: true
          description: Level 6 classification
        l7:
          type: string
          nullable: true
          description: Level 7 classification
        l8:
          type: string
          nullable: true
          description: Level 8 classification
        parent_id:
          type: integer
          nullable: true
        protein_class_desc:
          type: string
          description: Full hierarchical description
    TargetComponent:
      type: object
      description: A component (protein sequence) of a target
      properties:
        accession:
          type: string
          description: UniProt accession number
        component_description:
          type: string
          nullable: true
        component_id:
          type: integer
        component_type:
          type: string
          description: Component type (PROTEIN, DNA, RNA)
        relationship:
          type: string
          description: Relationship of this component to the target
        target_component_id:
          type: integer
  responses:
    BadRequest:
      description: Bad request - invalid query parameters
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: Resource not found
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
externalDocs:
  description: ChEMBL Web Services Documentation
  url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services