ChemSpider API

ChemSpider offers a powerful set of web services to access and query the database using your own information systems. Access to the ChemSpider API is free to academic users; for commercial use please contact us at

Some operations require a security token; to obtain a token please complete the registration process –when you are registered the Security Token is listed on the Profile page. For web services which require a “Service Subscriber” role, then email us above to discuss upgrading your user account.

  • Powerful Mass Spectrometry and Search web services include:

    • Search by molecular mass or elemental composition within ChemSpider or within particular data source(s)
    • Search by chemical identifier
    • Retrieving information about ChemSpider record(s)
    • Retrieving chemical structure thumbnail

    Full details of the MassSpec API and demo
    Full details of the Search API and demo

  • Spectra web services include:

    • Returns all Open Data spectral information from ChemSpider
    • Return spectral information on a compound
    • Returns identified spectra

    Full details of the Spectra web services

  • InChI and Generic chemical web services include:

    • Generation of a SMILES from a chemical structure
    • Generation of a chemical structure from a SMILES
    • Generation of an InChI from a chemical structure
    • Generation of a chemical structure from an InChI
    • Conversion between chemical data formats using OpenBabel

    Full details of the InChI web services and demo

If you would like ChemSpider to provide additional API functions, please email us as above and we’ll be happy to discuss if these can be provided.

Examples of ChemSpider API use

Below are some examples of the application of the web services above. Please note that you should URI encode any parameters that are passed into the ChemSpider webservices or you may get spurious results.

  • Perl script:

    See Example of ChemSpider web service use blog post for an example of a Perl script which access the SimpleSearch operation of the Search webservice

  • Java:

    See How to use ChemSpider webservices when programming with java blog post for how to make a java library based on the WSDL of ChemSpider’s web services (or download a ready made one) and for examples of its use.

  • Excel 2007 spreadsheet:

    See Demo of ChemSpider InChi to SMILES webservice invoked from Excel for a description of how to use the Office XP WebServices toolkit, and Visual Basic to set up a function in Excel which calls the InChIToSMILES operation of the InChI webservice

  • KNIME:

    See How to use ChemSpider webservices from Knime blog post for how to incorporate a call to a ChemSpider webservice to a KNIME workflow

  • .Net Client API for the ChemSpider Search web service:

    See New RSC ChemSpider search add-in for Accelrys Draw blog post to download a Visual Basic solution which contains a library for accessing the ChemSpider Search web service

  • Python wrapper:

    See ChemSpiPy blog post describing how to use the ChemSpider API with a Python wrapper

  • HTML search form:

    See Web API Example if you are a web developer who wants to incorporate a form into your own website which will perform an advanced search of ChemSpider using the Web API which will:

    • Search ChemSpider by structure or substructure
    • Search ChemSpider by chemical identifier
    • Search ChemSpider by molecular formula or molecular weight
    • Search ChemSpider by one of the predicted properties

Predicted Properties

We cannot provide any of the Predicted Properties that appear in a compound page that were generated using ACD/Labs as a web service, to be accessed directly programmatically, but if you are interested in this information then the Properties Prediction webpage allows you to query this information by entering a search term or drawing a structure.
The PhysChem properties prediction has been provided by Advanced Chemistry Development.

Predicted Properties include the following:

  • Molecular Weight
  • Molar Refractivity
  • Molar Volume
  • Parachor
  • Index of Refraction
  • Surface Tension
  • Density
  • Dielectric Constant (for hydrocarbons)
  • Polarizability
  • Monoisotopic, nominal mass, and average mass
    (these predictions using ACD/ChemSketch Properties Batchdefinitions available)


  • logP
  • BCF (Bioconcentration Factor)
  • Koc (Adsorption coefficient)
  • PSA (polar surface area)
  • FRB (freely rotatable bonds)
  • Number of H-bond donors
  • Number of H-bond acceptors
  • (these predictions using ACD/LogP Batchdefinitions available)
Predicted by ACD/Labs

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