By default, you can set only meta description to you Opencart's home page. With this extension you can set meta keywords for Opencart's home page, also.

DEMO:
http://ocdemos.womgoo.com/admin/
user:demo
pass:demo

Meta Keywords for home page can be set in System -> Settings -> Edit your store -> Store tab -> Meta Tag Keywords.

This extension is included in Opencart SEO PACK PRO. It contains 20+ extensions and you can save more than $100 by purchasing the full Opencart SEO PACK PRO:

http://www.opencart.com/index.php?route=extension/extension/info&extension_id=6182

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