Pay Attention: this extension is not compatible with OpenCart 3.0 at the moment!
Module Auto Translator allows translate all multilingual fields in opencart admin panel (default) . Administrator can translate fields (name, description, title, meta title, keywords, etc.) on edit page or use the automatic translation mode (bulk) in module settings.

Main advantages
✓ Easy installation (ocmod or vqmod version)
✓ Doesn't overwrite any opencart system files
✓ Support for 104 languages by Google API & 53 languages by Microsoft API
✓ Translation all multilingual fields in openсart admin panel
✓ Buttons translate and copy over each of multilingual field in admin panel
✓ Bulk translation (with logs):

• Selection of section (product category, option, etc.) with filtering by id, groups or selected items
• Selection of fields (name, description, title, keywords, etc.)
• Selection of language

Sections and fields for translation

• Product (Name, Description, Meta Tag Title, Meta Tag Description, Meta Tag Keywords, Tags, Attribute Text)
• Category (Name, Description, Meta Tag Title, Meta Tag Description, Meta Tag Keywords)
• Filter (Filter Name, Filter Group Name)
• Attribute (Attribute Name, Attribute Group Name)
• Option (Option Name, Option Value Name)
• Download (Download Name)
• Information (Title, Description, Meta Tag Title, Meta Tag Description, Meta Tag Keywords)
• Banner (Banner Image Title) - for versions 2.0.0.0-2.2.0.0
• Recurring Profile (Recurring Profile Name)
• Customer Group (Name, Description)
• Custom Field (Custom Field Name, Custom Field Value Name)
• Voucher Theme (Voucher Theme Name)
• Length Class (Length Title, Length Unit)
• Weight Class (Weight Title, Weight Unit)

Google Translate API

Price (source link)
For the use of Google Translate API will be charged fee (pricing) but at the moment of writing this manual, Google Cloud Platform have the free trial that allows you to get 300$ credit for free to use Google Cloud Platform services for 60 days, so for that amount using Google Translate API you will be able to translate 15-million characters ($20 per 1 million characters of text).

Limits (source link)
Content limits
Content to the Google Translation API is provided as text strings, and both pricing and usage are based on character counts. All characters sent to the Translation API, including whitespace characters, count towards these limits.

• 20,000,000 characters per month
• 2,000,000 characters per day
• 100,000 characters per 100 seconds

Attempting to process content in excess of the Text Content limit will produce an error. If you need to translate content in excess of these limits, please fill out a Google Cloud Translation API Quota Increase Request form.
Request limits
The current API usage limits for the Cloud Translation API are as follows (and are subject to change):

• 1000 requests per 100 seconds
• 800,000 requests per day

If you need to send requests in excess of these limits, please fill out a Google Cloud Translation API Quota Increase Request form.

Supported languages (source link)
Afrikaans, Albanian, Amharic, Arabic, Armenian, Azeerbaijani, Basque, Belarusian, Bengali, Bosnian, Bulgarian, Catalan, Chichewa, Chinese (Simplified), Chinese (Traditional), Corsican, Croatian, Czech, Danish, Dutch, English, Esperanto, Estonian, Filipino, Finnish, Frisian, Galician, Georgian, German, Greek, Gujarati, Haitian Creole, Hausa, Hawaiian, Hebrew, Hindi, Hungarian, Icelandic, Igbo, Indonesian, Irish, Japanese, Javanese, Kannada, Kazakh, Khmer, Korean, Kurdish, Kyrgyz, Lao, Latin, Latvian, Lithuanian, Luxembourgish, Macedonian, Malagasy, Malay, Malayalam, Maltese, Maori, Marathi, Mongolian, Burmese, Nepali, Norwegian, Pashto, Persian, Polish, Portuguese, Punjabi, Romanian, Russian, Samoan, Scots Gaelic, Serbian, Sesotho, Shona, Sindhi, Sinhala, Slovak, Slovenian, Somali, Spanish, Sundanese, Swahili, Swedish, Tajik, Tamil, Telugu, Thai, Turkish, Ukrainian, Urdu, Uzbek, Vietnamese, Welsh, Xhosa, Yiddish, Yoruba, Zulu

Microsoft Translator API

Price (source link)
Microsoft Translator is moving from the Microsoft Datamarket to the Azure Portal under the Cognitive Services category (28/10/16).
Azure Portal include:
• Subscriptions to the Microsoft Translator API will continue to be free (pricing) of charge for up to two million characters per month for Text Translation.
• New portal users can sign up for a free 30-day Azure account, which includes a $200 USD credit, or equivalent in your currency, to spend towards any Azure service.
• If you are a current Azure customer, you can include a subscription to the Microsoft Translator API as part of your overall Azure purchase.

Limits
The Microsoft Translator offer a free usage limit of 2 million characters per month and well as paid monthly subscriptions for higher volumes. Also, there is a limit of 10,000 characters for a single call to the microsoft translator api.

Supported languages (source link)
Afrikaans, Arabic, Bosnian (Latin), Bulgarian, Catalan, Chinese Simplified, Chinese Traditional, Croatian, Czech, Danish, Dutch, English, Estonian, Finnish, French, German, Greek, Haitian Creole, Hebrew, Hindi, Hmong Daw, Hungarian, Indonesian, Italian, Japanese, Kiswahili, Klingon, Klingon (pIqaD), Korean, Latvian, Lithuanian, Malay, Maltese, Norwegian, Persian, Polish, Portuguese, Querétaro Otomi, Romanian, Russian, Serbian (Cyrillic), Serbian (Latin), Slovak, Slovenian, Spanish, Swedish, Thai, Turkish, Ukrainian, Urdu, Vietnamese, Welsh, Yucatec Maya