Using the SP GET /authorization/v1/authorizationCode to call a SP API on behalf of a seller who already authorized me to call MWS


Hey there!

As per the SP documentation, I can use the GET /authorization/v1/authorizationCode endpoint to call a Selling Partner API on behalf of a seller who has already authorized me to call Amazon Marketplace Web Service (Amazon MWS). Which is the case I am working on.

I am sending a GET request to*************************

But I am faced with this 403 response

“errors”: [
“message”: “Access to requested resource is denied.”,
“code”: “MissingAuthenticationToken”

I’ve verified that the query parameter am sending for the mwsAuthToken and the Ids are correct

I’ve also gone through the instructions for registering a selling partner api application (By creating IAM User/ Roles/ Policies/ etc) and added the Role ARN to my application in the seller central account.

Thank you in advance for your help.


Thank you for reporting this @Glew. Were you (or anyone here) able to solve this? We’re having the same issue.


I am currently experiencing this issue as well


Referencing this, it looks like you need a published app in order to swap the MWS token for SP-API tokens.


@Harambay our app is published. So that shouldn’t be the issue.

No resolution just yet. @Droidox @Harambay -Have you guys figured out a solution?


I have an open case with Amazon and it has been pending response from Amazon since December.

Case number: 7800499431



Sorry, development of Amazon AWS API is not my area of expertise.


@Glew - No, we haven’t figured this out yet. So, with published app, you got it working? We plan to use our app by ourselves so we don’t plan to publish it.


Make sure you are signing every request, the issue i was having was that i wasn’t signing every request.

Its a bit complicated if you don’t already have something wrapping the new API for your language of choice. I decided to hold off on migrating over to SP-API till there is more support for Ruby.

Moderator Edit (Ricardo_Mod_Amazon): removed external URL.


We do sign the request and we use this wrapper


Yeah i saw him start that repo, it looks like the strongest ruby proj right now for SP-API, but i was hoping for an official SDK from Amazon. Looks like with there short time frame we will probably end up uzing amz_sp_api or at least forking it


@Harambay - Yes, our dev had submitted an issue on the repository and the owner confirmed our way is correct.

Let us know, if you ever get it working with only MWS API (as our Amazon Seller account isn’t active)


We had “MissingAuthenticationToken” - we were not getting an Access token before making the call to /authorizationCode.

Can’t see this documented anywhere at the moment. Reading the docs makes it look like your simply have to make a basic call with sellingPartnerId, DeveloperId and mwsAuthToken, but that’s not the case.

We’re no longer getting this error, but are now instead getting "“Developer ID xxxxxxxxxxxx is not associated with the application id”. This doesn’t really make any sense, but it might be because we’ve just converted existing app to hybrid, and Amazon haven’t approved this change yet. Shall have to wait and see on this. Can’t see anything else wrong with our set up.


Found the docs on this now (grantless operations):