OpenSubtitles
OpenSubtitles is part of the OPUS collection of open parallel corpora. It gathers subtitles from movies and television and aligns them across languages, giving you 2.6 billion sentences in 60 languages. Because subtitles are dialogue, the text captures how people actually speak, which makes it useful for conversational RAG, chat-style systems, and machine translation where you need aligned sentence pairs.
The corpus compilation is freely available for research, but the underlying subtitle content carries varied and sometimes unclear licensing, since the original subtitles were created by many different people. For that reason, treat commercial use as restricted and check the terms before building a product on it rather than a research prototype.
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