Jamba Large 1.5
Jamba Large 1.5 is the 398-billion-parameter member of the 1.5 family. It activates 94 billion parameters per token and supports a 256K context window.
Deprecated API; check access details
The release tested useful context, not only input capacity
Its card reports RULER results at lengths from 4K to 256K. The reported 256K score is 93.9. The tests assess whether the model can use information across a long input, rather than only accept that input.AI21-Jamba-Large-1.5 official model card
Practical guidance. A document workflow should also check missing evidence, contradictory passages and citations. A context benchmark does not cover every document type.
A finished instruction model
Large 1.5 supports tool calls, JSON responses and grounded generation. Unlike the original Jamba base checkpoint, it is presented as an instruction-following release.AI21-Jamba-Large-1.5 official model card
Legacy hosting and licensed weights
Amazon Bedrock marks the us-east-1 model Legacy from 26 May 2026 and schedules end of life for 26 November 2026. New adoption is restricted during the Legacy period.Amazon Bedrock lifecycle dates for legacy models
AI21's own dated API is deprecated. Downloadable weights remain subject to the Jamba Open Model License.AI21 Jamba versions, aliases and API deprecationsAI21-Jamba-Large-1.5 official model card
Specifications & access
| Detail | Value and conditions |
|---|---|
| Status | Deprecated API; check access details |
| Launch date | |
| Access | Downloadable, API |
| Model identifiers | AI21-Jamba-Large-1.5Jamba 1.5 Largejamba-large-1.5-2024-08ai21.jamba-1-5-large-v1:0 |
| Parameters | 398 billion total; 94 billion activeAI21-Jamba-Large-1.5 official model card |
| Context | 256K tokens advertisedAI21-Jamba-Large-1.5 official model card |
| Weight license | Jamba Open Model License; gated downloadAI21-Jamba-Large-1.5 official model card |
| AI21 API deprecation | 6 May 2025AI21 Jamba versions, aliases and API deprecations |
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