DeepL is a machine translation service from DeepL SE, a company founded in Cologne in 2017 by its CEO Jarek Kutylowski. Machine translation means that a computer model, not a person, translates text from one language to another. DeepL trains its own language models with proprietary methods and refines them with thousands of professional language experts.
People use the DeepL Translator in the browser or in desktop and mobile apps, and DeepL Write to improve their own writing. Programs use the DeepL API: they send text or HTML to an endpoint such as /v2/translate with a target language and receive the translation, with the source language detected automatically. Glossaries fix how certain terms are translated, and a formality setting chooses a formal or informal tone. The Document API translates files such as PDF, DOCX and PPTX and keeps their layout, and the Voice API transcribes and translates speech in real time. Official client libraries exist for Python, JavaScript, PHP, .NET, Java and Ruby.
DeepL is a hosted service. The API has a free plan and paid plans; the Translator apps are sold as subscriptions per user.