This document covers Notary application programming interface (Notary API) of the cloud platform.

What is Notary?

Notary is a cloud platform service that provides notarization, electronic signature and authenticity verification of files and Amazon S3 objects of any size by using the Ethereum blockchain. It includes public RESTful API that allows integrators to leverage its functionality programmatically. For more details on functionality and features of the service, refer to Notary Administrator’s Guide.

What can I do with the Notary API?

With this API, a service administrator can do the following:

  • Notarize a file:

    • By uploading it to a dedicated cloud storage (the notary storage).

    • By sending it to the notary service but without uploading it to the notary storage.

    • By sending its unique hash, instead of the entire contents, to the notary service.

  • Electronically sign an individual file uploaded to the notary storage or a file stored in a file-sharing resource and available by a permanent link (e.g., Google Docs, Dropbox).

  • Verify the authenticity of a file (check its notarization status):

    • By sending it to the notary service.

    • By sending its unique hash, instead of the entire contents, to the notary service.

  • Notarize and verify a JSON object.


    The guide does not cover this functionality as its logic is the same as the one of notarizing and verifying a file by its hash. For more information, see the API reference.

  • Manage files uploaded to the notary storage.

  • Manage API keys.


    API keys management is deprecated and will be removed in future versions. Use Bearer Authentication scheme instead.

Data format

The API uses the secure HTTP/1.1 over TLS 1.2 protocol and operates mostly with JSON-formatted messages.

Platform-specific codes

Responses may also include platform-specific error codes in addition to standard HTTP codes. Information about each code is available in “Status and error codes”.