Rate this page:

Cross Origin Resource Sharing (CORS)

Cross-Origin Resource Sharing is a security feature of modern browsers that keeps browser users secure. It prevents malicious activity like cross-site scripting. CORS implements headers in the response of any request to the server to say what domains are allowed to make specific types of calls to that server. In SendGrid's case, we do not allow our customers to make a browser-based call to our v3/mail/send endpoint.

Browser-Only Applications

When you have a browser-only application that reaches out to APIs, the API key has to be embedded in the application. Anyone with access to a browser-only application can access all of the Javascript source code, including your API keys.

Making your API key publicly accessible could result in anyone authenticating API calls with your API key — this is a significant security concern both for you and SendGrid.

Workarounds

You can create a server-based application, which will protect your API keys from being released to the world. Languages like NodeJS, PHP, Ruby, Python, C#, Go, and Java, and others can be implemented to make calls to the API from the security of a locked down server environment.

Rate this page:

Need some help?

We all do sometimes; code is hard. Get help now from our support team, or lean on the wisdom of the crowd browsing the SendGrid tag on Stack Overflow.

        
        
        

        Thank you for your feedback!

        We are always striving to improve our documentation quality, and your feedback is valuable to us. How could this documentation serve you better?

        Sending your feedback...
        🎉 Thank you for your feedback!
        Something went wrong. Please try again.

        Thanks for your feedback!

        Refer us and get $10 in 3 simple steps!

        Step 1

        Get link

        Get a free personal referral link here

        Step 2

        Give $10

        Your user signs up and upgrade using link

        Step 3

        Get $10

        1,250 free SMSes
        OR 1,000 free voice mins
        OR 12,000 chats
        OR more