What software are you using?

Anyway, for a Desktop app, you almost always use the "Implicit" (Client side) procedure.

1. Configure your Stack app as shown in this answer.

2. Your app appears to be set for "Implicit" (server side) OAuth. Unless it is acting as -- or on -- a full web server, this is incorrect. Attempt to set it for client side OAuth.

3. In that vein, key parameters are:

   • Client ID:                {Your app's Client ID}
   • Client Secret:         Not applicable
   • Redirect URI:         https://stackexchange.com/oauth/login_success
   • Authorization URL: https://stackexchange.com/oauth/dialog?scope=private_info

4. Worry about the the "retrieve token parameters" and "refresh token parameters" when the rest of the setup works. Not sure Stack Apps and whatever you are using, are on the same page...

5. The "API call parameters" setting needs more information. For client side OAuth and most API calls, the parameters should be in the URL (A GET request). But for write operations (editing or creating posts, comments, etc.) then POST is required and Header is correct.

What software are you using?

Anyway, for a Desktop app, you almost always use the "Implicit" (Client side) procedure.

1. Configure your Stack app as shown in this answer.

2. That dialog appears to be set for "Implicit" (server side) OAuth. Unless it is acting as -- or on -- a full web server, this is incorrect. Attempt to set it for client side OAuth.

3. In that vein for client-side OAuth, key parameters are:

   • Client ID:                {Your app's Client ID}
   • Client Secret:         Not applicable
   • Redirect URI:         https://stackexchange.com/oauth/login_success
   • Authorization URL: https://stackexchange.com/oauth/dialog?scope=private_info
     (Or use whatever scope is required for your needs.)

4. Worry about the the "retrieve token parameters" and "refresh token parameters" when the rest of the setup works. Not sure Stack Apps and whatever you are using, are on the same page...

5. The "API call parameters" setting needs more information. For client side OAuth and most API calls, the parameters should be in the URL (A GET request). But for write operations (editing or creating posts, comments, etc.) then POST is required and Header is correct.