Getting started with Royal Society of Chemistry web services  

Use our web services to enrich your apps, in-house systems and workflow tools with data held by the Royal Society of Chemistry.

ChemSpider APIs re-born 

As the first set of web services to be released, we are replacing our legacy ChemSpider SOAP APIs with new RESTful APIs. The new APIs provide a better interface to work with ChemSpider data.

By moving to our redesigned ChemSpider APIs, you will benefit from:

  • Better performance, as the APIs are now built upon an industry-leading API platform
  • Clearer, more concise and more-logically structured endpoints
  • Improved request payload validation and error handling
  • Secure access (HTTPS)
  • Better user experience and support materials for developers

Start Using the APIs

The Royal Society of Chemistry web services are now out of the preview period.

Standard accounts can make 1000 calls per month.

If you want an increased allowance, or if you have any feedback on the services, please contact us.

Using our new APIs

If you have used our ChemSpider APIs before then you will probably have received an email from us with details of how to update your software to use our new REST APIs.

Register for a new account
Create your API key in My Keys
Click on Get Started in the top menu




Search chemical structures

Use our name to structure service to allow a user to enter a name or other identifier and return a chemical structure

Search by chemical mass or formula

Search for all the structures with a particular molecular mass or molecular formula

Access chemical properties

Get structures and other information about a record



Our API Plans




Compare with the old ChemSpider APIs

ChemSpider Search API New API  (
AsyncSimpleSearch (input: Name) /filter/name
AsyncSimpleSearch  (input: InChI) /filter/InChI
AsyncSimpleSearch (input: InChIKey) /filter/InChIKey
AsyncSimpleSearch (input: SMILES) /filter/SMILES
AsyncSimpleSearchOrdered (input: Name) /filter/name
AsyncSimpleSearchOrdered (input: InChI) /filter/InChI
AsyncSimpleSearchOrdered (input: InChIKey) /filter/InChIKey
AsyncSimpleSearchOrdered (input: SMILES) /filter/SMILES
CSID2ExtRefs /records/{recordId}/externalreferences
GetAsyncSearchResultPart /filter/{queryId}/results
GetAsyncSearchStatus /filter/{queryId}/status
GetAsyncSearchStatusAndCount /filter/{queryId}/status
GetCompoundInfo /records/{recordId}/details
GetCompoundThumbnail  /records/{recordId}/image
GetRecordDetails /records/{recordId}/details
IntrinsicPropertiesSearch /filter/intrinsicproperty
SimpleSearch  (input: Name) /filter/name
SimpleSearch (input: InChI) /filter/InChI
SimpleSearch (input: InChIKey) /filter/InChIKey
SimpleSearch (input: SMILES) /filter/SMILES
SimpleSearch2IdList /filter/name


ChemSpider InChI API New API  (
CSIDToMol /records/{recordId}/mol
InChIKeyToCSID /filter/InChIKey
InChIKeyToInChI /tools/convert
InChIKeyToMol /tools/convert
InChIToCSID /filter/InChI
InChIToInChIKey /tools/convert
InChIToMol /tools/convert
InChIToSMILES /tools/convert
IsValidInChIKey /tools/validate/InChIKey
MolToInChI /tools/convert
MolToInChIKey /tools/convert
SMILESToInChI /tools/convert


ChemSpider MassSpec API New API  (
GetCompressedRecordsSdf /filter/{queryId}/results/sdf
GetDatabases /lookups/datasources
GetExtendedCompoundInfo /records/{recordId}/details
GetExtendedCompoundInfoArray /records/batch
GetExtendedMolCompoundInfoArray /records/batch
GetFormulaArrayAsyncSearchResultPart /filter/formula/batch/{queryId}/result
GetMassArrayAsyncSearchResultPart /filter/mass/batch/{queryId}/results
GetRecordMol /records/{recordId}/mol
SearchByFormula /filter/formula
SearchByFormula2 /filter/formula
SearchByFormulaArrayAsyncOrdered /filter/formula/batch
SearchByFormulaAsync /filter/formula
SearchByFormulaAsyncOrdered /filter/formula
SearchByMass /filter/mass
SearchByMass2 /filter/mass
SearchByMassArrayAsyncOrdered /filter/mass/batch
SearchByMassAsync /filter/mass
SearchByMassAsyncOrdered /filter/mass