Translation tools translate typed text, selections or screenshots without switching to a browser. Many call online engines such as DeepL, Google or large language models, while some can use Apple's built-in translation. A global shortcut that translates selected text is the feature most people look for.
DeepL's desktop app translates text and documents with its own engine. Easydict is an open source dictionary and translator that queries several services, and OpenAI Translator uses LLM APIs with your own key. Grammarly checks English writing rather than translating. Check which services need API keys and whether your text is sent to a cloud provider.