OmegaT - OmegaT is a free open-source translation memory application for professional translators written in Java.
Google Translate - Google's free service instantly translates words, phrases, and web pages between English and over 100 other languages.
Crowdin - Localize your product in a seamless way
LibreTranslate - LibreTranslate is a free and open-source and self-hostable machine translation server. It also has a public instance designed for personal or infrequent use.
Transifex - Transifex makes it easy to collect, translate and deliver digital content, web and mobile apps in multiple languages. Localization for agile teams.
DeepL Translator - DeepL Translator is a machine translator that currently supports 42 language combinations.