ChEMBL website screenshot

ChEMBL

ChEMBL is a manually curated database of bioactive molecules with drug-like properties, maintained by the EMBL-EBI. It provides a REST API for accessing bioactive molecules, drug targets, bioactivity data, approved drugs, clinical trial compounds, and cheminformatics utilities to support drug discovery research.

ChEMBL publishes 16 APIs on the APIs.io network, including Activity API, Assay API, ATC Classification API, and 13 more. Tagged areas include Drug Discovery, Bioactivity, Molecules, Cheminformatics, and Life Sciences.

The ChEMBL catalog on APIs.io includes 1 Spectral governance ruleset.

ChEMBL’s developer surface includes authentication, status page, and 4 more developer resources.

🌐 Visit website 📡 Source on GitHub
35.4/100 thin ▼ -5.3 Agent 31/100 agent aware Full breakdown ↓
scored 2026-07-28 · rubric v0.6
AccessFree
16 APIs
Drug DiscoveryBioactivityMoleculesCheminformaticsLife SciencesBioinformaticsPharmacologyEMBL-EBI

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-28 · rubric v0.6
Composite quality — 35.4/100 · thin
Contract Quality 12.9 / 25
Developer Ergonomics 2.2 / 20
Commercial Clarity 7.9 / 20
Operational Transparency 0.0 / 13
Governance 7.0 / 12
Discoverability 8.2 / 10
Agent readiness — 31/100 · agent aware
Machine-Readable Contract 18 / 18
Agentic Access Contract 10 / 10
MCP Server 0 / 12
Machine-Readable Auth 10 / 10
Idempotency 0 / 9
Stable Error Semantics 0 / 8
Request/Response Examples 0 / 7
Rate-Limit Signaling 7 / 7
Typed Event Surface 0 / 6
Agent Skills 0 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3
A2A Agent Card 0 / 8
Dry-Run / Simulate Mode 0 / 4
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/chembl: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 16

Individual APIs this provider publishes, each with its own machine-readable definition.

ChEMBL Activity API

Activity values recorded in assays, linking molecules to targets with quantitative bioactivity measurements.

ChEMBL Assay API

Experimental protocols and result details from source documents and datasets.

ChEMBL ATC Classification API

WHO Anatomical Therapeutic Chemical classification for drugs.

ChEMBL Binding Site API

Target binding site definitions used in assays.

ChEMBL Cell Line API

Cell line information used in assays.

ChEMBL Compound Record API

Occurrence of a compound in a specific source document.

ChEMBL Document API

Source documents and datasets from which assay data is derived.

ChEMBL Drug API

Approved drug information including applicants, patent numbers, and research codes.

ChEMBL Drug Indication API

Drug-disease associations with clinical trial and regulatory references.

ChEMBL Drug Warning API

Safety information for withdrawn or black-box warned drugs.

ChEMBL Mechanism API

Mechanism of action information for approved drugs.

ChEMBL Molecule API

Chemical molecules including properties, structural representations, synonyms, and drug-like properties.

ChEMBL Similarity API

Molecule similarity searching using Tanimoto coefficient.

ChEMBL Status API

API operational status and ChEMBL database version information.

ChEMBL Substructure API

Molecular substructure searching.

ChEMBL Target API

Protein and non-protein targets defined in assays.

Scroll for all 16

Pricing Plans 1

Published pricing tiers and plan structures.

Plans

1 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Rate Limits

0 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Finops

FINOPS

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

ChEMBL API Rules

5 rules · 4 warnings 1 info

SPECTRAL

JSON Schema 3

Standalone JSON Schema definitions for this provider's data models.

ChEMBL Activity

28 properties

JSON SCHEMA

ChEMBL Molecule

20 properties

JSON SCHEMA

ChEMBL Target

8 properties

JSON SCHEMA

Examples 3

Example request and response payloads for these APIs.

Activity Example

2 fields

EXAMPLE

Molecule Example

2 fields

EXAMPLE

Similarity Search Example

4 fields

EXAMPLE

Security Posture 1

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Chembl Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Chembl Agentic Access

30 operations

30 operations · 0 acting

AGENTIC

Resources

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess
AgenticAccess

Design & Contract 1

Pagination, idempotency, versioning, errors, and events

Build 1

SDKs, sample code, and the tooling you integrate with

PythonClient
PythonClient

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity
DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Status
Status

Commercial 2

Pricing, plans, and the legal terms of use

License
License
 TermsOfService
TermsOfService

Other 2

Properties that don't map to a standard resource type

Source (apis.yml)

apis.yml Raw ↑ 
name: ChEMBL
description: ChEMBL is a manually curated database of bioactive molecules with drug-like properties, maintained by the EMBL-EBI.
  It provides a REST API for accessing bioactive molecules, drug targets, bioactivity data, approved drugs, clinical trial
  compounds, and cheminformatics utilities to support drug discovery research.
accessModel:
  pricing: free
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Free
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
image: https://www.ebi.ac.uk/chembl/static/chembl/img/chembl_logo.png
url: https://www.ebi.ac.uk/chembl/
created: '2026-06-13'
modified: '2026-06-13'
specificationVersion: '0.19'
apis:
- aid: chembl:chembl-activity-api
  name: ChEMBL Activity API
  description: Activity values recorded in assays, linking molecules to targets with quantitative bioactivity measurements.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Activity
  properties:
  - type: OpenAPI
    url: openapi/chembl-activity-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-assay-api
  name: ChEMBL Assay API
  description: Experimental protocols and result details from source documents and datasets.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Assay
  properties:
  - type: OpenAPI
    url: openapi/chembl-assay-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-atc-classification-api
  name: ChEMBL ATC Classification API
  description: WHO Anatomical Therapeutic Chemical classification for drugs.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - ATC Classification
  properties:
  - type: OpenAPI
    url: openapi/chembl-atc-classification-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-binding-site-api
  name: ChEMBL Binding Site API
  description: Target binding site definitions used in assays.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Binding Site
  properties:
  - type: OpenAPI
    url: openapi/chembl-binding-site-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-cell-line-api
  name: ChEMBL Cell Line API
  description: Cell line information used in assays.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Cell Line
  properties:
  - type: OpenAPI
    url: openapi/chembl-cell-line-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-compound-record-api
  name: ChEMBL Compound Record API
  description: Occurrence of a compound in a specific source document.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Compound Record
  properties:
  - type: OpenAPI
    url: openapi/chembl-compound-record-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-document-api
  name: ChEMBL Document API
  description: Source documents and datasets from which assay data is derived.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Document
  properties:
  - type: OpenAPI
    url: openapi/chembl-document-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-drug-api
  name: ChEMBL Drug API
  description: Approved drug information including applicants, patent numbers, and research codes.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Drug
  properties:
  - type: OpenAPI
    url: openapi/chembl-drug-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-drug-indication-api
  name: ChEMBL Drug Indication API
  description: Drug-disease associations with clinical trial and regulatory references.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Drug Indication
  properties:
  - type: OpenAPI
    url: openapi/chembl-drug-indication-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-drug-warning-api
  name: ChEMBL Drug Warning API
  description: Safety information for withdrawn or black-box warned drugs.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Drug Warning
  properties:
  - type: OpenAPI
    url: openapi/chembl-drug-warning-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-mechanism-api
  name: ChEMBL Mechanism API
  description: Mechanism of action information for approved drugs.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Mechanism
  properties:
  - type: OpenAPI
    url: openapi/chembl-mechanism-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-molecule-api
  name: ChEMBL Molecule API
  description: Chemical molecules including properties, structural representations, synonyms, and drug-like properties.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Molecule
  properties:
  - type: OpenAPI
    url: openapi/chembl-molecule-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-similarity-api
  name: ChEMBL Similarity API
  description: Molecule similarity searching using Tanimoto coefficient.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Similarity
  properties:
  - type: OpenAPI
    url: openapi/chembl-similarity-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-status-api
  name: ChEMBL Status API
  description: API operational status and ChEMBL database version information.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Status
  properties:
  - type: OpenAPI
    url: openapi/chembl-status-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-substructure-api
  name: ChEMBL Substructure API
  description: Molecular substructure searching.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Substructure
  properties:
  - type: OpenAPI
    url: openapi/chembl-substructure-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
- aid: chembl:chembl-target-api
  name: ChEMBL Target API
  description: Protein and non-protein targets defined in assays.
  humanURL: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  baseURL: https://www.ebi.ac.uk/chembl/api/data/
  tags:
  - Target
  properties:
  - type: OpenAPI
    url: openapi/chembl-target-api-openapi.yml
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/chembl-data-web-services
  - type: TermsOfService
    url: https://www.ebi.ac.uk/about/terms-of-use/
  - type: Documentation
    url: https://chembl.gitbook.io/chembl-interface-documentation/web-services/cheminformatic-utils-web-services
common:
- type: AgenticAccess
  url: agentic-access/chembl-agentic-access.yml
- type: DomainSecurity
  url: security/chembl-domain-security.yml
- type: Authentication
  value: None - public API, no key required
- type: Formats
  value: JSON, XML, YAML, SDF (compounds), SVG (images)
- type: Pagination
  value: Offset-based pagination with configurable limit (default 20 records per page)
- type: Filtering
  value: URL-friendly query language with operators including exact, contains, startswith, endswith, regex, gt/gte, lt/lte,
    range, in, isnull, and full-text search
- type: License
  url: https://creativecommons.org/licenses/by-sa/3.0/
  value: Creative Commons Attribution-ShareAlike 3.0 Unported
- type: TermsOfService
  url: https://www.ebi.ac.uk/about/terms-of-use/
- type: PythonClient
  url: https://github.com/chembl/chembl_webresource_client
  value: Official Python client available via pip install chembl_webresource_client
- type: Status
  url: https://www.ebi.ac.uk/chembl/api/data/status/
maintainers:
- FN: ChEMBL Team
  email: chembl-help@ebi.ac.uk
  url: https://www.ebi.ac.uk/chembl/
tags:
- Drug Discovery
- Bioactivity
- Molecules
- Cheminformatics
- Life Sciences
- Bioinformatics
- Pharmacology
- EMBL-EBI