Granite 4.0 H Small

Granite 4.0 H Small is IBM's flagship open-weight language model of the Granite 4.0 generation, released October 2025. It uses a hybrid architecture that mixes Mamba-2 state-space layers with a minority of transformer attention layers in roughly a 9:1 ratio, with 32B total parameters and 9B active per token. IBM reports the hybrid design cuts memory requirements for long-context and multi-session inference by over 70 percent versus conventional transformers.

The model ships under the Apache 2.0 license with cryptographically signed checkpoints, and IBM describes Granite as the first open model family to receive ISO 42001 certification for AI management. It targets enterprise workloads where throughput and memory efficiency matter more than raw scale, with native support on vLLM and other common runtimes.