PubChem

name: PubChem
description: PubChem is NCBI's open chemistry database containing information on more than 100 million chemical compounds.
  It provides REST and view APIs for searching chemical structures, retrieving molecular properties, bioactivity data, safety
  information, and drug information. PubChem integrates data from hundreds of data sources and is freely accessible without
  authentication for standard use.
image: https://pubchem.ncbi.nlm.nih.gov/favicon.ico
tags:
- Chemistry
- Chemical Compounds
- Drug Discovery
- Bioassay
- Life Sciences
- NCBI
- Bioinformatics
url: https://pubchem.ncbi.nlm.nih.gov/
created: '2026-06-13'
modified: '2026-06-13'
specificationVersion: '0.19'
apis:
- name: PubChem PUG REST API
  description: The Power User Gateway (PUG) REST API provides programmatic access to PubChem compound, substance, and bioassay
    data. Supports lookup by name, CID, SID, InChI, SMILES, and structure search. Returns molecular properties, identifiers,
    2D/3D structures, bioactivity summaries, cross-references, synonyms, and images.
  humanURL: https://pubchem.ncbi.nlm.nih.gov/docs/pug-rest
  baseURL: https://pubchem.ncbi.nlm.nih.gov/rest/pug
  tags:
  - Compounds
  - Substances
  - Bioassays
  - Structure Search
  - Chemical Properties
  properties:
  - type: Documentation
    url: https://pubchem.ncbi.nlm.nih.gov/docs/pug-rest
  - type: OpenAPI
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug/openapi.json
  contact:
  - FN: PubChem Help Desk
    email: pubchem-help@ncbi.nlm.nih.gov
  operations:
  - summary: Get compound by CID
    method: GET
    path: /compound/cid/{cid}/JSON
    description: Retrieve full compound record by PubChem Compound ID (CID) in JSON format.
  - summary: Get compound by name
    method: GET
    path: /compound/name/{name}/JSON
    description: Retrieve compound records by chemical name, returning CID and full compound data.
  - summary: Get compound by SMILES
    method: GET
    path: /compound/smiles/{smiles}/JSON
    description: Retrieve compound records by canonical SMILES string.
  - summary: Get compound by InChI
    method: GET
    path: /compound/inchi/{inchi}/JSON
    description: Retrieve compound records by IUPAC International Chemical Identifier.
  - summary: Get compound properties
    method: GET
    path: /compound/cid/{cid}/property/{properties}/JSON
    description: Retrieve selected calculated properties (MolecularFormula, MolecularWeight, CanonicalSMILES, InChI, InChIKey,
      IUPACName, XLogP, TPSA, etc.) for a compound.
  - summary: Get compound synonyms
    method: GET
    path: /compound/cid/{cid}/synonyms/JSON
    description: Retrieve all synonyms and alternative names for a compound.
  - summary: Get compound SIDs
    method: GET
    path: /compound/cid/{cid}/sids/JSON
    description: Retrieve all substance IDs (SIDs) associated with a compound.
  - summary: Get compound cross-references
    method: GET
    path: /compound/cid/{cid}/xrefs/{xreftypes}/JSON
    description: Retrieve external cross-references (RegistryID, RN, PubMedID, MMDBID, ProteinGI, NucleotideGI, TaxonomyID,
      MIMID, GeneID, ProbeID, PatentID) for a compound.
  - summary: Get compound image
    method: GET
    path: /compound/cid/{cid}/PNG
    description: Retrieve a 2D structure image of a compound in PNG format.
  - summary: Get compound bioassay summary
    method: GET
    path: /compound/cid/{cid}/assaysummary/JSON
    description: Retrieve a summary of bioassay results for a compound, including activity outcomes and assay metadata.
  - summary: Substructure search
    method: GET
    path: /compound/substructure/smiles/{smiles}/JSON
    description: Search for compounds containing a specified substructure using SMILES, InChI, or SDF input. Returns async
      listkey for large result sets.
  - summary: Superstructure search
    method: GET
    path: /compound/superstructure/smiles/{smiles}/JSON
    description: Search for compounds that are superstructures of the specified structure.
  - summary: Similarity search
    method: GET
    path: /compound/fastsimilarity_2d/smiles/{smiles}/JSON
    description: Fast 2D Tanimoto similarity search for structurally similar compounds.
  - summary: Get substance by SID
    method: GET
    path: /substance/sid/{sid}/JSON
    description: Retrieve a substance record by PubChem Substance ID (SID), including source information, synonyms, and associated
      compound.
  - summary: Get substance synonyms
    method: GET
    path: /substance/sid/{sid}/synonyms/JSON
    description: Retrieve all synonyms for a substance record.
  - summary: Get assay by AID
    method: GET
    path: /assay/aid/{aid}/JSON
    description: Retrieve a full bioassay record by Assay ID (AID), including protocol, results schema, and experimental data.
  - summary: Get assay description
    method: GET
    path: /assay/aid/{aid}/description/JSON
    description: Retrieve descriptive metadata for a bioassay, including title, protocol, target information, and measurement
      parameters.
  - summary: Get assay results
    method: GET
    path: /assay/aid/{aid}/CSV
    description: Retrieve bioassay experimental results in CSV format with all tested substance outcomes and activity values.
  - summary: Retrieve async results by listkey
    method: GET
    path: /compound/listkey/{listkey}/cids/JSON
    description: Poll for and retrieve results from an asynchronous structure search query using the listkey returned during
      the search initiation.
- name: PubChem PUG View API
  description: The PUG View API provides access to the full structured compound and substance pages as seen on the PubChem
    website, organized as hierarchical sections covering names, structures, physical and chemical properties, safety data,
    pharmacology, biological activities, toxicology, literature references, and more.
  humanURL: https://pubchem.ncbi.nlm.nih.gov/docs/pug-view
  baseURL: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view
  tags:
  - Compound Data
  - Safety Data
  - Pharmacology
  - Toxicology
  - Structured Data
  properties:
  - type: Documentation
    url: https://pubchem.ncbi.nlm.nih.gov/docs/pug-view
  contact:
  - FN: PubChem Help Desk
    email: pubchem-help@ncbi.nlm.nih.gov
  operations:
  - summary: Get full compound data page
    method: GET
    path: /data/compound/{cid}/JSON
    description: Retrieve all structured data for a compound as seen on its PubChem compound page, organized in hierarchical
      sections.
  - summary: Get compound data section
    method: GET
    path: /data/compound/{cid}/JSON
    description: Retrieve a specific section of a compound data page using the heading parameter (e.g., Safety+and+Hazards,
      Pharmacology+and+Biochemistry, Chemical+and+Physical+Properties).
  - summary: Get full substance data page
    method: GET
    path: /data/substance/{sid}/JSON
    description: Retrieve all structured data for a substance record in hierarchical section format.
  - summary: Get annotations by heading
    method: GET
    path: /annotations/heading/{heading}/JSON
    description: Retrieve annotations across all compounds for a specific data heading (e.g., Boiling+Point, LogP, Melting+Point).
  - summary: Get data in XML format
    method: GET
    path: /data/compound/{cid}/XML
    description: Retrieve full compound structured data in XML format.
  - summary: Get data in ASNT format
    method: GET
    path: /data/compound/{cid}/ASNT
    description: Retrieve full compound structured data in ASN.1 text format for programmatic parsing.
- name: PubChem PUG SOAP API
  description: Legacy SOAP/XML web service interface for PubChem providing structure search, identity search, and chemical
    standardization capabilities. Supports submitting queries and retrieving results in ASN.1, XML, and SDF formats.
  humanURL: https://pubchem.ncbi.nlm.nih.gov/pug/pugsoap.cgi?wsdl
  baseURL: https://pubchem.ncbi.nlm.nih.gov/pug/pugsoap.cgi
  tags:
  - SOAP
  - Legacy
  - Structure Search
  - Chemical Standardization
  properties:
  - type: Documentation
    url: https://pubchem.ncbi.nlm.nih.gov/docs/pug-soap
  - type: WSDL
    url: https://pubchem.ncbi.nlm.nih.gov/pug/pugsoap.cgi?wsdl
  contact:
  - FN: PubChem Help Desk
    email: pubchem-help@ncbi.nlm.nih.gov
- name: PubChem Structure Image Service
  description: Generates 2D and 3D structure images for chemical compounds by CID, SID, SMILES, or InChI. Returns PNG images
    at configurable sizes, suitable for embedding in applications and documents.
  humanURL: https://pubchem.ncbi.nlm.nih.gov/docs/pug-rest#section=PNG
  baseURL: https://pubchem.ncbi.nlm.nih.gov/rest/pug
  tags:
  - Structure Images
  - 2D Structures
  - Visualization
  properties:
  - type: Documentation
    url: https://pubchem.ncbi.nlm.nih.gov/docs/pug-rest#section=PNG
  contact:
  - FN: PubChem Help Desk
    email: pubchem-help@ncbi.nlm.nih.gov
  operations:
  - summary: Get compound 2D structure image by CID
    method: GET
    path: /compound/cid/{cid}/PNG
    description: Returns a PNG image of the 2D chemical structure for the given compound ID. Size can be controlled with the
      image_size parameter.
  - summary: Get compound image by name
    method: GET
    path: /compound/name/{name}/PNG
    description: Returns a PNG image of the 2D chemical structure for a compound looked up by name.
  - summary: Get compound image by SMILES
    method: GET
    path: /compound/smiles/{smiles}/PNG
    description: Returns a PNG image of the 2D chemical structure for the compound specified by SMILES string.
- name: PubChem Identifier Exchange Service
  description: Bulk identifier conversion service for translating between PubChem CIDs, SIDs, and external identifiers such
    as CAS Registry Numbers, ChEMBL IDs, ChEBI IDs, and other registry identifiers at scale.
  humanURL: https://pubchem.ncbi.nlm.nih.gov/idexchange/idexchange.cgi
  baseURL: https://pubchem.ncbi.nlm.nih.gov/idexchange
  tags:
  - Identifier Conversion
  - CAS Numbers
  - ChEMBL
  - ChEBI
  - Registry IDs
  properties:
  - type: Documentation
    url: https://pubchem.ncbi.nlm.nih.gov/docs/identifier-exchange-service
  contact:
  - FN: PubChem Help Desk
    email: pubchem-help@ncbi.nlm.nih.gov
common:
- type: TermsOfService
  url: https://www.nlm.nih.gov/web_policies.html
- type: PrivacyPolicy
  url: https://www.nlm.nih.gov/privacy.html
- type: Status
  url: https://pubchem.ncbi.nlm.nih.gov/
- type: Support
  url: https://support.nlm.nih.gov/
- type: Signup
  url: https://www.ncbi.nlm.nih.gov/account/
- type: GitHub
  url: https://github.com/ncbi
- type: Blog
  url: https://pubchemblog.wordpress.com/
- type: Documentation
  url: https://pubchem.ncbi.nlm.nih.gov/docs/
- type: FAQ
  url: https://pubchem.ncbi.nlm.nih.gov/docs/faq
- type: RateLimits
  url: https://pubchem.ncbi.nlm.nih.gov/docs/programmatic-access#section=Request-Volume-Limitations
- type: Plans
  url: plans/plans.yml
- type: RateLimits
  url: rate-limits/rate-limits.yml
- type: FinOps
  url: finops/finops.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com