Для начала сразу готовый код. Если кому-то нужно просто скопировать и не париться с вопросами ЧТО и ЗАЧЕМ. Не забудьте только поменять domen.com на ваш домен.
ROBOTS.TXT ДЛЯ OPENCART 2.*
User-agent: * Disallow: /*route=account/ Disallow: /*route=affiliate/ Disallow: /*route=checkout/ Disallow: /*route=product/search Disallow: /index.php?route=product/product*&manufacturer_id= Disallow: /admin Disallow: /catalog Disallow: /system Disallow: /*?sort= Disallow: /*&sort= Disallow: /*?order= Disallow: /*&order= Disallow: /*?limit= Disallow: /*&limit= Disallow: /*?filter_name= Disallow: /*&filter_name= Disallow: /*?filter_sub_category= Disallow: /*&filter_sub_category= Disallow: /*?filter_description= Disallow: /*&filter_description= Disallow: /*?tracking= Disallow: /*&tracking= Disallow: /*compare-products Disallow: /*search Disallow: /*cart Disallow: /*checkout Disallow: /*login Disallow: /*logout Disallow: /*vouchers Disallow: /*wishlist Disallow: /*my-account Disallow: /*order-history Disallow: /*newsletter Disallow: /*return-add Disallow: /*forgot-password Disallow: /*downloads Disallow: /*returns Disallow: /*transactions Disallow: /*create-account Disallow: /*recurring Disallow: /*address-book Disallow: /*reward-points Disallow: /*affiliate-forgot-password Disallow: /*create-affiliate-account Disallow: /*affiliate-login Disallow: /*affiliates Allow: /catalog/view/javascript/ Allow: /catalog/view/theme/*/ Allow: /*.css Allow: /*.js Allow: /*.jpg Allow: /*.jpeg Allow: /*.png Sitemap: https://domen.com/sitemap.xml User-agent: Yandex Disallow: /*route=account/ Disallow: /*route=affiliate/ Disallow: /*route=checkout/ Disallow: /*route=product/search Disallow: /index.php?route=product/product*&manufacturer_id= Disallow: /admin Disallow: /catalog Disallow: /system Disallow: /*?sort= Disallow: /*&sort= Disallow: /*?order= Disallow: /*&order= Disallow: /*?limit= Disallow: /*&limit= Disallow: /*?filter_name= Disallow: /*&filter_name= Disallow: /*?filter_sub_category= Disallow: /*&filter_sub_category= Disallow: /*?filter_description= Disallow: /*&filter_description= Disallow: /*compare-products Disallow: /*search Disallow: /*cart Disallow: /*checkout Disallow: /*login Disallow: /*logout Disallow: /*vouchers Disallow: /*wishlist Disallow: /*my-account Disallow: /*order-history Disallow: /*newsletter Disallow: /*return-add Disallow: /*forgot-password Disallow: /*downloads Disallow: /*returns Disallow: /*transactions Disallow: /*create-account Disallow: /*recurring Disallow: /*address-book Disallow: /*reward-points Disallow: /*affiliate-forgot-password Disallow: /*create-affiliate-account Disallow: /*affiliate-login Disallow: /*affiliates Allow: /catalog/view/javascript/ Allow: /catalog/view/theme/*/ Allow: /*.css Allow: /*.js Allow: /*.jpg Allow: /*.jpeg Allow: /*.png Clean-param: tracking Sitemap: https://domen.com/sitemap.xml
ROBOTS.TXT ДЛЯ OPENCART 3.*
User-agent: * Disallow: /*route=account/ Disallow: /*route=affiliate/ Disallow: /*route=checkout/ Disallow: /*route=product/search Disallow: /index.php?route=product/product*&manufacturer_id= Disallow: /admin Disallow: /catalog Disallow: /system Disallow: /*?sort= Disallow: /*&sort= Disallow: /*?order= Disallow: /*&order= Disallow: /*?limit= Disallow: /*&limit= Disallow: /*?filter_name= Disallow: /*&filter_name= Disallow: /*?filter_sub_category= Disallow: /*&filter_sub_category= Disallow: /*?filter_description= Disallow: /*&filter_description= Disallow: /*?tracking= Disallow: /*&tracking= Disallow: /*compare-products Disallow: /*search Disallow: /*cart Disallow: /*checkout Disallow: /*login Disallow: /*logout Disallow: /*vouchers Disallow: /*wishlist Disallow: /*my-account Disallow: /*order-history Disallow: /*newsletter Disallow: /*return-add Disallow: /*forgot-password Disallow: /*downloads Disallow: /*returns Disallow: /*transactions Disallow: /*create-account Disallow: /*recurring Disallow: /*address-book Disallow: /*reward-points Disallow: /*affiliate-forgot-password Disallow: /*create-affiliate-account Disallow: /*affiliate-login Disallow: /*affiliates Disallow: /*?pdf= Allow: /catalog/view/javascript/ Allow: /catalog/view/theme/*/ Allow: /*.css Allow: /*.js Allow: /*.jpg Allow: /*.jpeg Allow: /*.png Sitemap: https://domen.com/sitemap.xml User-agent: Yandex Disallow: /*route=affiliate/ Disallow: /*route=checkout/ Disallow: /*route=product/search Disallow: /index.php?route=product/product*&manufacturer_id= Disallow: /admin Disallow: /catalog Disallow: /system Disallow: /*?sort= Disallow: /*&sort= Disallow: /*?order= Disallow: /*&order= Disallow: /*?limit= Disallow: /*&limit= Disallow: /*?filter_name= Disallow: /*&filter_name= Disallow: /*?filter_sub_category= Disallow: /*&filter_sub_category= Disallow: /*?filter_description= Disallow: /*&filter_description= Disallow: /*compare-products Disallow: /*search Disallow: /*cart Disallow: /*checkout Disallow: /*login Disallow: /*logout Disallow: /*vouchers Disallow: /*wishlist Disallow: /*my-account Disallow: /*order-history Disallow: /*newsletter Disallow: /*return-add Disallow: /*forgot-password Disallow: /*downloads Disallow: /*returns Disallow: /*transactions Disallow: /*create-account Disallow: /*recurring Disallow: /*address-book Disallow: /*reward-points Disallow: /*affiliate-forgot-password Disallow: /*create-affiliate-account Disallow: /*affiliate-login Disallow: /*affiliates Disallow: /*?pdf= Allow: /catalog/view/javascript/ Allow: /catalog/view/theme/*/ Allow: /*.css Allow: /*.js Allow: /*.jpg Allow: /*.jpeg Allow: /*.png Clean-param: tracking Sitemap: https://domen.com/sitemap.xml
Как правило, указанных настроек достаточно для прекрасной и правильной индексации сайта на Opencart поисковыми системами. Можно добавить в него отдельно правила для Гугл-бота, но только если у вас есть специфические для него правила, не покрываемые разделом User-agent: *
И не забудьте в модулях включить Google Sitemap, чтобы XML карта вашего сайта заработала.