Apertus 1.5

The multimodal successor to Apertus, released 24 July 2026 in 8B and 70B sizes. Produced by continued pretraining of Apertus 1.0 — adding a multimodal mix of 4T tokens to the 8B and 2T to the 70B on top of the original 15T — so it keeps the same architecture: a decoder-only transformer with the xIELU activation and the AdEMAMix optimizer, trained exclusively on fully open data.

Three firsts for the family: native multimodal input (image and audio understanding, text output), an optional thinking mode for reasoning tasks, and a 262,144-token context (a 4× jump over Apertus 1.0's 65K). The improved post-training recipe also strengthens instruction-following and tool use. Still Apache 2.0, still positioned as Switzerland's fully open, transparent, EU-AI-Act-aligned sovereign model line.

Detailed benchmark results are promised "in the coming weeks"; the models are not yet scored on the Artificial Analysis Intelligence Index.