# Apertus 1.5

Switzerland's Apertus project released 1.5 versions of its 8B and 70B models, continuing pretraining from 1.0 to add image and audio understanding, an optional thinking mode, and a context window of 262,144 tokens. Multimodality arrives by early fusion: images and audio become discrete tokens placed in the same sequence as text, with no separate vision encoder, so the architecture is unchanged and training runs at text-only speed. The models read images and audio but generate only text, speech handling remains experimental, and the project says the release still trails frontier open-weight models.

Switzerland's Apertus project released 1.5 versions of its 8B and 70B models, continuing pretraining from 1.0 to add image and audio understanding, an optional thinking mode, and a context window of 262,144 tokens. Multimodality arrives by early fusion: images and audio become discrete tokens placed in the same sequence as text, with no separate vision encoder, so the architecture is unchanged and training runs at text-only speed. The models read images and audio but generate only text, speech handling remains experimental, and the project says the release still trails frontier open-weight models.