Definition

Mixture of Experts (MoE) is a neural network architecture where only a subset of model parameters (“experts”) activate per inference token, enabling very large total parameter counts with manageable compute per request. Sparse MoE designs route each token to a small number of expert layers.

Key Characteristics

  1. Total vs active parameters: Large total count (e.g., 310B) with small active subset (e.g., 15B) per forward pass
  2. Efficiency: Lower inference cost than dense models of equivalent capability
  3. Scaling: Enables frontier-class models without proportional compute increase

MiMo-V2.5 (Xiaomi, April 2026)

  • MiMo-V2.5: 310B total parameters, 15B active, 1M token context, natively multimodal
  • MiMo-V2.5-Pro: ~1.02T parameters, 42B active, hybrid-attention architecture
  • MIT-licensed; pricing from $0.40/M input tokens (among cheapest frontier models)
  • Powers mimo-code MiMo Auto channel (free limited-time)
  • Post-training includes “harness awareness” — model trained to manage memory within agent scaffolds

Sources