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models / compare / kimi-k3-vs-gpt-oss-120b

Kimi K3 vs gpt-oss-120b

How Kimi K3 (Moonshot AI, July 2026) and gpt-oss-120b (OpenAI, August 2025) are built, drawn on the same November 2026 blueprint. They make different choices on 15 of 27 components. Select a component in either diagram to find it in the table.

--- frontier-llm@2026-11+++ kimi-k3@2026-07+0~5−3

Kimi K3

Moonshot AI, July 2026, 2.8T total, 104B active

Text · code · tool outputText · code · tool outputImages · video · audioImages · video · audioByte-level BPE tokenizer — 128K–262K vocabByte-level BPE tokenizer128K–262K vocabVision / audio encoder — native ViT or encoder-free patchesVision / audio encodernative ViT or encoder-free patchesToken embedding — media embeds spliced in placeToken embeddingmedia embeds spliced in placeEngram n-gram memory — hashed 2–4-gram lookup (V4.1)Engram n-gram memoryhashed 2–4-gram lookup (V4.1)Block Attention Residuals (AttnRes) — Residual & normBlock Attention Residuals (AttnRes)Residual & normRMSNorm — pre-normRMSNormpre-normQK-Clip and normalized latents (no per-head QK-Norm) — Residual & normQK-Clip and normalized latents (no per…Residual & normPartial RoPE / NoPE — rotate 64 dims, or nonePartial RoPE / NoPErotate 64 dims, or noneGated DeltaNet / KDA — linear · ~3 of every 4 layersGated DeltaNet / KDAlinear · ~3 of every 4 layersLatent attention (MLA) — global · GQA in many modelsLatent attention (MLA)global · GQA in many modelsSparse / compressed attn — DSA indexer · CSA / HCASparse / compressed attnDSA indexer · CSA / HCASliding-window attention — local · 128–1,024-token windowSliding-window attentionlocal · 128–1,024-token windowOutput gate + sink — σ(x·W_g) ⊙ o · learnable sinkOutput gate + sinkσ(x·W_g) ⊙ o · learnable sink⊕ residual⊕residualRMSNorm — pre-normRMSNormpre-normSigmoid router with Quantile Balancing — Mixture of expertsSigmoid router with Quantile BalancingMixture of expertsStable LatentMoE routed experts (SiTU-GLU) — Mixture of expertsStable LatentMoE routed experts (SiTU-…Mixture of expertsShared expert — 1–2 · always activeShared expert1–2 · always active⊕ residual⊕residualFinal RMSNormFinal RMSNormLM head — untied · vocab logitsLM headuntied · vocab logitsMTP layer turned EAGLE-3 drafter (not in open weights) — Input & outputMTP layer turned EAGLE-3 drafter (not…Input & outputNext-token logitsNext-token logitsDraft tokensDraft tokensMuon optimizer — Newton–Schulz · QK-Clip · per-headMuon optimizerNewton–Schulz · QK-Clip · per-headFP8 → FP4 training — block-scaled FP8 · MXFP4/NVFP4 QATFP8 → FP4 trainingblock-scaled FP8 · MXFP4/NVFP4 QATLong-context extension — staged 4K → 1M · YaRNLong-context extensionstaged 4K → 1M · YaRNRL with verifiable rewards — GRPO family · async agentic RLRL with verifiable rewardsGRPO family · async agentic RLOn-policy distillation — reverse KL to specialist teachersOn-policy distillationreverse KL to specialist teachersSpeculative decoding — MTP self-drafting · DSparkSpeculative decodingMTP self-drafting · DSparkKV-cache compression — FP4 KV · cross-layer reuse · SSDKV-cache compressionFP4 KV · cross-layer reuse · SSD
AttentionMixture of expertsResidual & normInput & outputTraining & inferenceData flowResidual / skipAddedReplacedNot used

--- frontier-llm@2026-11+++ gpt-oss-120b@2025-08+0~4−9

gpt-oss-120b

OpenAI, August 2025, 117B total, 5.1B active

Text · code · tool outputText · code · tool outputImages · video · audioImages · video · audioByte-level BPE tokenizer — 128K–262K vocabByte-level BPE tokenizer128K–262K vocabVision / audio encoder — native ViT or encoder-free patchesVision / audio encodernative ViT or encoder-free patchesToken embedding — media embeds spliced in placeToken embeddingmedia embeds spliced in placeEngram n-gram memory — hashed 2–4-gram lookup (V4.1)Engram n-gram memoryhashed 2–4-gram lookup (V4.1)Single residual stream — Residual & normSingle residual streamResidual & normRMSNorm — pre-normRMSNormpre-normQK-Norm — per-head RMSNorm on q, kQK-Normper-head RMSNorm on q, kFull RoPE with YaRN scaling — AttentionFull RoPE with YaRN scalingAttentionGated DeltaNet / KDA — linear · ~3 of every 4 layersGated DeltaNet / KDAlinear · ~3 of every 4 layersDense grouped-query attention — AttentionDense grouped-query attentionAttentionSparse / compressed attn — DSA indexer · CSA / HCASparse / compressed attnDSA indexer · CSA / HCASliding-window attention — local · 128–1,024-token windowSliding-window attentionlocal · 128–1,024-token windowOutput gate + sink — σ(x·W_g) ⊙ o · learnable sinkOutput gate + sinkσ(x·W_g) ⊙ o · learnable sink⊕ residual⊕residualRMSNorm — pre-normRMSNormpre-normSoftmax top-k router — Mixture of expertsSoftmax top-k routerMixture of expertsRouted experts — top-6–22 of 256–896 · SwiGLURouted expertstop-6–22 of 256–896 · SwiGLUShared expert — 1–2 · always activeShared expert1–2 · always active⊕ residual⊕residualFinal RMSNormFinal RMSNormLM head — untied · vocab logitsLM headuntied · vocab logitsMTP module(s) — predict t+2 … t+kMTP module(s)predict t+2 … t+kNext-token logitsNext-token logitsDraft tokensDraft tokensMuon optimizer — Newton–Schulz · QK-Clip · per-headMuon optimizerNewton–Schulz · QK-Clip · per-headFP8 → FP4 training — block-scaled FP8 · MXFP4/NVFP4 QATFP8 → FP4 trainingblock-scaled FP8 · MXFP4/NVFP4 QATLong-context extension — staged 4K → 1M · YaRNLong-context extensionstaged 4K → 1M · YaRNRL with verifiable rewards — GRPO family · async agentic RLRL with verifiable rewardsGRPO family · async agentic RLOn-policy distillation — reverse KL to specialist teachersOn-policy distillationreverse KL to specialist teachersSpeculative decoding — MTP self-drafting · DSparkSpeculative decodingMTP self-drafting · DSparkKV-cache compression — FP4 KV · cross-layer reuse · SSDKV-cache compressionFP4 KV · cross-layer reuse · SSD
AttentionMixture of expertsResidual & normInput & outputTraining & inferenceData flowResidual / skipAddedReplacedNot usedNot disclosed

Component by component

Kimi K3 and gpt-oss-120b differ on 15 of 27 components.

Blueprint componentKimi K3gpt-oss-120b

Same as the blueprintMoonViT-V2: a 27-layer, 401M-parameter ViT (14-px patches, width 1,024, 12 heads) with RMSNorm and no bias terms, trained from scratch with the language-model loss instead of a SigLIP initialization. Images and video share weights (factorized spatial/temporal attention, temporal pooling); a 2×2 pixel shuffle cuts tokens 4× before an MLP projector, allowing inputs up to 3,584 × 3,584 px.

Not used

Block Attention Residuals (AttnRes)Each sublayer reads a softmax-weighted mix of the embedding and earlier 12-layer block summaries, not one running sum.

Single residual streamOne d = 2,880 residual stream with pre-norm sublayers; no hyper-connections.

QK-Clip and normalized latents (no per-head QK-Norm)No per-head RMSNorm on q and k: MLA logits are held by K2's weight clipping, KDA's q and k are L2-normalized.

Not used

Same as the blueprintNoPE throughout. The 24 MLA layers apply no rotary or other positional encoding (the 64-dim decoupled key slot of MLA is kept but never rotated), and KDA's decay and short convolutions carry order. Context therefore extends to 1M tokens without RoPE rescaling or YaRN.

Full RoPE with YaRN scalingRotary embeddings on all 64 head dims, θ = 150,000, stretched 32× with YaRN.

Same as the blueprintKDA in 69 of 93 layers (three of every four, starting at layer 1): 96 heads with 128-dim q, k, v and a 128 × 128 state per head; short conv (kernel 4) + SiLU on q, k, v; L2-normalized q, k. K3 bounds the per-channel log-decay as g = −5·σ(eᴬ·z) instead of Kimi Linear's −eᴬ·softplus(z), which keeps 16-token-tile rescaling inside BF16 range so every intra-chunk tile runs as a tensor-core matmul.

Not used

Same as the blueprintGated MLA in 24 layers: every fourth layer (4, 8, …, 92) plus layer 93. 96 heads; queries via a 1,536-dim latent, keys and values from a 512-dim latent plus a 64-dim shared key slot (576 cached values per token per layer); q/k head dim 192, v head dim 128. The attention output is kept in FP32 during training to avoid flash attention's biased rounding.

Dense grouped-query attentionFull causal attention with 64 query heads sharing 8 KV heads, in every other block.

Not used

Same as the blueprintEvery other block (18 of 36) attends only to a banded window of the last 128 tokens, alternating with the dense blocks; same GQA head layout.

Sigmoid router with Quantile BalancingSigmoid scores pick 16 of 896 experts; each expert's selection bias is reset every step from a quantile of routing margins.

Softmax top-k routerA linear router picks the top 4 of 128 experts; softmax over those 4 logits gives the weights.

Stable LatentMoE routed experts (SiTU-GLU)896 SiTU-GLU experts run in a 3,584-dim latent (half of d); 16 fire per token; an RMSNorm precedes the up-projection.

Same as the blueprint128 experts, top-4 active, each a SwiGLU with intermediate size 2,880. The gate is clamped at 7.0 and the linear branch to ±7.0, combined as (x_lin + 1) · x_glu · σ(1.702 · x_glu). Expert weights ship in MXFP4.

Same as the blueprintTwo full-width shared experts per MoE layer, stored fused as one SiTU-GLU MLP with intermediate size 6,144 (2 × 3,072) at d = 7,168. They read the un-projected input, are ungated and stay in BF16.

Not used

MTP layer turned EAGLE-3 drafter (not in open weights)One pretrained MTP layer is fine-tuned into an EAGLE-3-style draft model that reads features from three depths.

Not used

Same as the blueprintPer-Head Muon: momentum of the Q, K and V projections is split along the head dimension and each head's block is orthogonalized separately, equalizing update scale across heads; other matrices use standard Muon. Pretraining also keeps Kimi K2's weight-clipping mechanism, a cosine LR schedule with 1% linear warmup and weight decay 0.1.

Not disclosed

Same as the blueprintMulti-teacher on-policy distillation merges the nine domain × effort experts: for a sampled domain and effort level, the matching teacher scores each student token with the clipped log-ratio clip(sg(log π_teacher − log π_θ), −R_max, R_max), used as a dense reward inside the RL framework. Top-k distillation objectives showed no advantage.

Not disclosed

Same as the blueprintSpeculative decoding uses the EAGLE-3-style drafter fine-tuned from the MTP layer. For KDA rollback, the serving kernel caches only the draft tokens' projected inputs and replays them on-chip to rebuild the accepted state, instead of snapshotting the state at every draft position.

Not used

Same as the blueprintOnly the 24 MLA layers keep a per-token cache: 576 values per token per layer, 13,824 per token in total (~27 KiB in BF16). Each KDA layer holds a fixed 96 × 128 × 128 state per sequence. Serving packs KDA states into the same paged pool as MLA pages, matches prefixes at 512-token granularity and checkpoints KDA states at a sparse subset of those boundaries; RL rollouts spill idle prefixes to a CPU-DRAM pool.

Not used

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