🪶 Soofi S 30B-A3B

A sovereign, open-source Mixture-of-Experts hybrid Mamba–Transformer foundation model for German and English

A Sovereign, Open-Source Foundation Model for German and English

Soofi S Pretraining Report v1.0

Core Team: Benedikt Droste10, David Fitzek3,9, Ruben Härle5, Lukas Helff2,5, Maximilian Idahl10, Alex Jude3,9, Abbas Goher Khan3, Maurice Kraus5, Timm Ruland3,9, Richard Rutmann3,9, Sebastian Sztwiertnia5

Contributors: Markus Frey3,9, Daniil Gurgurov2, Jan Pfister6, Tom Röhr7, Sebastian von Rohrscheidt7

Advisors: Jörg Bienert1, Nicolas Flores-Herr3, Simon Gottschalk8, Andreas Hotho6, Kristian Kersting2,5,11, Joachim Köhler3, Alexander Löser7, Wolfgang Nejdl8, Simon Ostermann2, Jan Plogsties4, Patrick Putzky12

Technical Leads: Mehdi Ali3, Michael Fromm3, Max Lübbering3,9

1KI Bundesverband, 2DFKI, 3Fraunhofer IAIS, 4Fraunhofer IIS, 5Technische Universität Darmstadt, 6Universität Würzburg, 7Berliner Hochschule für Technik, 8L3S Research Center, 9Lamarr, 10ellamind, 11hessian.AI, 12Merantix Momentum

Consortium coordinated by the KI Bundesverband. Funded by the German Federal Ministry for Economic Affairs and Energy (BMWE) in the context of IPCEI-CIS and 8ra.

Soofi S 30B-A3B is a sovereign, open-source Mixture-of-Experts (MoE) hybrid Mamba–Transformer foundation model for German and English. Its hybrid design activates only 3B of 30B parameters per token and keeps the inference cache near-constant as context grows, giving it a decisive throughput advantage over dense models for long-context, high-concurrency deployment.

Pretrained on roughly 27 trillion tokens with deliberately up-weighted German, Soofi S matches dense 14–27B models on aggregate English and German benchmarks, achieves the best code aggregates in both languages among 17 open base models, and outperforms every European sovereign baseline in our comparison — including ones far larger in active parameters. Among fully open models, it obtains the highest English and German evaluation scores, ahead of Olmo 3 32B and Apertus 70B. Soofi S was built end-to-end on the German Industrial AI Cloud, a sovereign HPC-scale AI infrastructure operated by Deutsche Telekom in Munich.

📌 At a Glance

Parameters

31.6B total
3.2B active

Architecture

52 layers
23 Mamba-2 · 23 MoE · 6 GQA

Pretraining

~26.68T tokens
DE up to 15.3%

Context

up to 1M
tokens

🧩 Highlights

  1. 🏆 German–English champion: best English and German code aggregates among all 17 measured open base models; strongest fully open model on the English and German aggregates; matches or outperforms every European sovereign baseline on every German benchmark in our suite — at a fraction of the active-parameter cost of dense 14–27B models.
  2. 📋 Full data transparency: complete per-source, per-language token accounting for all three training phases (including sources we evaluated and excluded), with reproducible corpus construction scripts. ~99% of the mixture can be independently reconstructed.
  3. 🔁 Reproducible recipe: full Warmup–Stable–Decay learning-rate schedule, optimizer, all hyperparameters, per-phase token budgets, and phase boundaries — a third party can rebuild the run.
  4. ⚡ Long-context serving efficiency: only 6 of 52 layers keep a KV cache, so the per-sequence cache stays near-constant with context length. Measured aggregate decode TPS/GPU is 8–9× that of dense 14–24B models at 40K context (batch 32) and stays essentially flat from 4K to 256K.
  5. 🇩🇪 Sovereign end to end: trained from 24 March to 13 May 2026 on up to 512 NVIDIA B200 GPUs of the German Industrial AI Cloud (Deutsche Telekom, Munich), under European operational and data-protection requirements.

📊 Results

📁 Available Artifacts

All artifacts are released under permissive licenses for transparent audit and extension.

📜 Citation

If you use Soofi S or its artifacts, please cite the report (PDF):

@techreport{soofi2026soofis,
  title       = {A Sovereign, Open-Source Foundation Model for German and English: Soofi S Pretraining Report v1.0},
  author      = {{The Soofi-Team}},
  institution = {Project Soofi},
  year        = {2026},
  note        = {\url{https://huggingface.co/Soofi-Project}}
}