Jamba 1.5 Large
AI21 LabsAI21-Jamba-1.5-Large (ai21labs/AI21-Jamba-1.5-Large on HF), hybrid SSM-Transformer (Mamba+Attention) MoE, 398B total / 94B active, 256K context, instruction-tuned chat model with tool use / grounded-RAG / JSON mode. Announced 22 Aug 2024 under the Jamba Open Model License. Verified live on HF June 2026, but stale: superseded by Jamba 1.6 (Mar 2025) and the Jamba2/Jamba Reasoning 3B generation now headlined on ai21.com/jamba. Recategorized from base_pretrained -> finetuned_chat: this is the instruct/chat SKU (post-trained for downstream chat/agentic use), not a raw base model.
AI21-Jamba-1.5-Large (ai21labs/AI21-Jamba-1.5-Large on HF), hybrid SSM-Transformer (Mamba+Attention) MoE, 398B total / 94B active, 256K context, instruction-tuned chat model with tool use / grounded-RAG / JSON mode. Announced 22 Aug 2024 under the Jamba Open Model License. Verified live on HF June 2026, but stale: superseded by Jamba 1.6 (Mar 2025) and the Jamba2/Jamba Reasoning 3B generation now headlined on ai21.com/jamba. Recategorized from base_pretrained -> finetuned_chat: this is the instruct/chat SKU (post-trained for downstream chat/agentic use), not a raw base model.
Openness
3 high confidence- weights
- open(downloadable on HF, contact-info gate)
- data
- closed
- code
- partial(inference/usage only, no training pipeline)
- license
- Jamba-Open-Model-License(non-OSI: $50M annual-revenue commercial cap + AUP + naming/attribution requirements)
Weights downloadable under the Jamba Open Model License: non-OSI, with a $50M annual-revenue cap that bars large-entity commercial use. The 'Open Model' branding overstates it. Moved from 2/restricted on 2026-08-01 by the universal license scale, which caps a bounded commercial license at 3 rather than 2. The test at that boundary is whether the license permits commercial use AT ALL: this one does, for everyone inside the bound. A license that forbids commerce outright - CC-BY-NC, Mistral Non-Production - stays at 2. Nine other products carry a bounded license and all now score 3; four of them were already recorded there, which is the inconsistency this resolves.
- https://huggingface.co/ai21labs/AI21-Jamba-1.5-Large recorded 2026-06-04
Jamba Open Model License + downloadable Safetensors weights, instruction-following model card
- https://www.ai21.com/licenses/jamba-open-model-license recorded 2026-06-04
non-OSI license text: $50M annual-revenue commercial cap, AUP, naming/attribution clauses
Adoption
1 high confidenceWeights downloadable under the Jamba Open Model License: non-OSI, with a $50M annual-revenue cap that bars large-entity commercial use. The 'Open Model' branding overstates it. Moved from 2/restricted on 2026-08-01 by the universal license scale, which caps a bounded commercial license at 3 rather than 2. The test at that boundary is whether the license permits commercial use AT ALL: this one does, for everyone inside the bound. A license that forbids commerce outright - CC-BY-NC, Mistral Non-Production - stays at 2. Nine other products carry a bounded license and all now score 3; four of them were already recorded there, which is the inconsistency this resolves.
- https://huggingface.co/ai21labs/AI21-Jamba-1.5-Large recorded 2026-06-04
~1,072 downloads last month on the official model card
Capability
3 medium confidenceWeights downloadable under the Jamba Open Model License: non-OSI, with a $50M annual-revenue cap that bars large-entity commercial use. The 'Open Model' branding overstates it. Moved from 2/restricted on 2026-08-01 by the universal license scale, which caps a bounded commercial license at 3 rather than 2. The test at that boundary is whether the license permits commercial use AT ALL: this one does, for everyone inside the bound. A license that forbids commerce outright - CC-BY-NC, Mistral Non-Production - stays at 2. Nine other products carry a bounded license and all now score 3; four of them were already recorded there, which is the inconsistency this resolves.
- https://www.ai21.com/blog/announcing-jamba-model-family/ recorded 2026-06-04
Arena Hard 65.4 for Jamba 1.5 Large, beats Llama 3.1 70B/405B; Jamba Open Model License
- https://huggingface.co/ai21labs/AI21-Jamba-1.5-Large recorded 2026-06-04
MMLU 81.2, GSM-8K 87, 256K RULER context on model card
Unchanged since 2026-08-07 (last edited, not re-checked)