How to add contextual gadget on personal gmail

Question

Can we use contextual gadget on my personal gmail OR do I have to purchase and app domain for this?

My mainfeast.json is

     {
  "manifest_version": 2,
  "name": "unsendMe-AddContact",
  "version": "0.0.0.2",
  "description": "Grab the contact of the mail sender and save .",
   "icons": {
    "128": "ICON_PLACE3 (2) (Custom) (2).png",
    "16": "ICON_PLACE3 (2) (Custom).png"
  },
 "container": ["app"],
  "api_console_project_id": "xxxxxxxxxx"
}

Answer 1

Gmail Contextual Gadgets are not available on your personal email. You will need to purchase an enterprise account.

Your manifest doesn't look right - you should check out the link below for the full details:

https://developers.google.com/gmail/contextual_gadgets#hello_world_example_manifest