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Create a Meta App
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Go to http://developers.facebook.com > My Apps > Create App. Select the "Business" type and follow the prompts on your screen.
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Locate the WhatsApp product on the newly created app's dashboard and click Set up.
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Next, you will see the option to select an existing Business Manager (if you have one) or, if you would like, the onboarding process can create one automatically for you (you can customize your business later, if needed). Make a selection and click Continue.
Tada! 🎉 Your Meta App with WhatsApp product has been successfully created!
Send a Test Message
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On the Getting Started tab, select your test phone number in the From field.
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Add the phone number you would like to message in the To field.
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Click Send Message to send the first message. As an alternative, you can copy the code sample provided and execute it in your terminal or in Postman.
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That’s it! You have just sent a test message! 
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