1. Search for “google cloud console”

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2. Click the first result03. Login to your account if needed04. Click on the “Console” button on the top-right corner

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5. Select your project from the top-left corner dropdown

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6. Click the option icon and at the top-left corner

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7. Click the “APIs and services” option

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8. Click on the “OAuth consent screen” option from the left panel

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9. Chose “External” and click “Create”

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10. Provide the necessary informations and click “SAVE AND CONTINUE” for the next two steps and click “BACK TO DASHBOARD” for the last step

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11. Now click on “Credentials“

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12. Click on “CREATE CREDENTIALS” then “OAuth client ID“

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13. Select Android from the dropdown option and provide the necessary info. Then click “CREATE“

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14. Sometimes creating credentials with release SHA-1 will not able to Sign-In in app debug mode. So Try building the app and then try Google Sign-in. If you are using App signing key certificate from google play store then also create a OAuth using Sha-1 key from Play store.

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15. Next steps for IOS.

16. Create another “OAuth client ID“. This time Select “IOS” and provide the necessary info and Click “CREATE“.

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17. In the Google cloud console, click on the OAuth credential you created for your ios app

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18. Only copy this first section

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19. Open project/ios/Runner/Info.plist in any editor, Search for “google-reversed-client-Id-for-SignIn” and replace with the copied id from step 18

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24. Run your app and it should be working with Google Sign-In now.