OpenCart have inbuilt SEO friendly URLs feature. To enable SEO URLs in OpenCart follow these steps. Also make sure you have mod_rewrite module enabled already. If it’s not consult your hosting company.
1. Rename your htaccess.txt to .htaccess.
2. If you have installed OpenCart in a sub directory then edit “RewriteBase /” in .htaccess
2) Log into admin area.
3) Go to Admin->Configuration->Settings->Server and check SEO URL option Yes.
4) Then you have to enter SEO keyword field in every products/categories/information etc. on edit forms. Refer attached screen shot.