# Invalid Signature with Sample Web App

**URL:** <https://devforum.zoom.us/t/invalid-signature-with-sample-web-app/4005>\
**Category:** Web\
**Created:** [April 23, 2019, 1:35am UTC](https://devforum.zoom.us/t/invalid-signature-with-sample-web-app/4005 "2019-04-23T01:35:44Z")\
**Posts on this page:** 1\
**Showing post:** 28

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**Author:** ![tommy](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/tommy/32/72769_2.png) [@tommy](https://devforum.zoom.us/u/tommy)\
**Post date:** [January 16, 2020, 8:28pm UTC](https://devforum.zoom.us/t/invalid-signature-with-sample-web-app/4005/28 "2020-01-16T20:28:44Z")

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Hey @mchrenko,

Yes it does sound like an issue generating the signature.

> [@mchrenko](#):
>
> Can you please be more specific when we **must** use JWT (and how to use it) and when we can use generating signature from sample code?

To use the Web SDK, you need to use a JWT App Type Key and Secret to [generate the signature](https://marketplace.zoom.us/docs/sdk/native-sdks/web/essential/signature) to authenticate.

To call the [Zoom APIs](https://marketplace.zoom.us/docs/api-reference/introduction), you can use the J[WT Token.](https://devforum.zoom.us/t/how-to-create-jwt-token-using-rest-api-in-c/6620/4)

Can you share the code you are using to generate the signature so I can help debug? Also make sure to use a real meeting ID.

Thanks,  
Tommy

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