Language-Agnostic SEntence Representations.

LASER is a library to calculate multilingual sentence embeddings.

Currently, we include an encoder which supports nine European languages:

  • Germanic languages: English, German, Dutch, Danish
  • Romanic languages: French, Spanish, Italian, Portuguese
  • Uralic languages: Finnish

All these languages are encoded by the same BLSTM encoder, and there is no need to specify the input language (but tokenization is language specific). According to our experience, the sentence encoder supports code-switching, i.e. the same sentences can contain words in several different languages.

We have also some evidence that the encoder generalizes somehow to other languages of the Germanic and Romanic language families (e.g. Swedish, Norwegian, Afrikaans, Catalan or Corsican), although no data of these languages was used during training.

A detailed description how the multilingual sentence embeddings are trained can be found in.


Python 3 with NumPy
PyTorch 0.40
Faiss (for mining bitexts)
tokenization from the Moses encoder and byte-pair-encoding


  • set the environment variable 'LASER' to the root of the installation, e.g. export LASER="${HOME}/projects/laser"
  • download encoders from Amazon s3
  • download third party software
  • download the data used in the examples tasks (see description for each task)