Z.ai (Zhipu AI) · usage rank #1 · released 2026-08-26
GLM-5.3-Flash
What GLM-5.3-Flash’s own documents say it is built from — every method with the sentence that describes it.
Curator’s note320B total / 18B active, the first natively multimodal model in the GLM-5 series and a newly trained base rather than a post-training refresh. First GLM to use a hybrid sparse + linear attention stack, plus Manifold-Constrained Hyper-Connections (mHC) for scaling efficiency, over a 30T-token multimodal pre-training corpus. 1M context, MIT. Architecture id glm5_next; no 5.3-Flash report — arXiv 2602.15763 is the GLM-5 lineage report and the blog carries the 5.3-Flash delta.
Rank by open-weight tokens on OpenRouter, week of 2026-09-21.
Against the consensus recipe
Its documents state 4 of the 15 methods the field agrees on.
The recipe from the overview: the methods the most labs adopt, per stage. A missing one is something the documents do not say, not something the model lacks.
Data curation
- Agentic data synthesis pipelinenot in its documents
Training objective
- Multi-Token Predictionnot in its documents
- KL alignment lossnot in its documents
Model architecture
- Mixture of Expertscore
- Hybrid Attentioncore
- Multi-Token Predictionnot in its documents
Optimization
- Muonnot in its documents
- Expert Parallelismnot in its documents
- Cosine decaynot in its documents
Post-training
- Group Relative Policy Optimizationnot in its documents
- Supervised fine-tuningnot in its documents
- Multi-Teacher On-Policy Distillationnot in its documents
Inference & serving
- Configurable reasoning effortdefault
- Speculative decodingnot in its documents
- FP8 KV-cache quantizationoptional
Checked in its code
Its code shows 10 of the 19 architecture features checked — 9 of them are not stated in its documents.
Documents say what a lab chose to describe; the modeling code says what the checkpoint runs. Each feature below was put to a code verifier, and only the config values and source lines it cited that were found in the files are shown, linked to the line.
Read from Hugging Face Transformers (modeling_glm5_next.py, configuration_glm5_next.py) and config.json at revision eb9eb208eb, by anthropic/claude-sonnet-5 on 2026-09-25.
| Feature | Code | Its documents | Evidence |
|---|---|---|---|
| Grouped-query attention | not in its code | not stated | num_attention_heads equals num_key_value_heads (64 == 64) and the config even enforces this in validate_architecture, so no query-head grouping occurs; the attention is MLA-style, not GQA. text_config.num_attention_heads = 64text_config.num_key_value_heads = 64 |
| Multi-head latent attention code only | in its code | not stated | Softmax attention layers use DeepSeek-V2-style latent KV compression (kv_lora_rank=512, q_lora_rank=1536) with kv_b_proj up-projection per head, as implemented in Glm5NextTextAttention. text_config.kv_lora_rank = 512text_config.q_lora_rank = 1536 |
| Sliding-window attention | not in its code | not stated | No sliding_window config key or windowed masking mechanism exists anywhere in this model's code; layer types are only linear_attention and deepseek_sparse_attention (indexed_attention). |
| Interleaved sliding-window and global attention | not in its code | not stated | There is no sliding-window layer type in layer_types (only linear_attention and deepseek_sparse_attention), so no interleaving of sliding and global attention exists. text_config.layer_types = ["linear_attention", "linear_attention", "linear_attention", "deepseek_sparse… |
| Indexer-selected sparse attention (DeepSeek Sparse Attention) code only | in its code | not stated | A Glm5NextTextIndexer lightweight indexer scores pooled candidate tokens and each query attends only to the resulting top-k selection (index_topk=2048) in deepseek_sparse_attention layers. text_config.index_topk = 2048text_config.index_n_heads = 32text_config.index_head_dim = 128 |
| Linear-attention or state-space layers alongside full attention code only | in its code | not stated | layer_types alternates linear_attention (KDA) layers with deepseek_sparse_attention (MLA+indexer) softmax layers across the 45 decoder layers. text_config.layer_types = ["linear_attention", "linear_attention", "linear_attention", "deepseek_sparse… |
| Gated DeltaNet layers code only | in its code | not stated | Glm5NextTextLinearAttention implements Kimi Delta Attention (a gated delta-rule variant) with a forget gate decay and delta-rule state update, used in linear_attention layers. |
| Mamba-2 layers | not in its code | not stated | No Mamba-2 SSD selective state-space block exists; the linear-attention layers implement Kimi Delta Attention instead, and no mamba_num_heads/ssm_state_size config or code is present. |
| Learnable attention sink | not in its code | not stated | No learned per-head sink logit or extra denominator column appears anywhere in eager_attention_forward or the attention modules. |
| Gated attention output | not in its code | not stated | The softmax-attention (Glm5NextTextAttention/MLA) path has no sigmoid gate on its output before o_proj; the only sigmoid output gate found is in the linear-attention (KDA) path via RMSNormGated, which is a separate mixer, not gated softmax attention output. |
| QK normalization | code unclear | not stated | The DSA indexer applies LayerNorm to its key projection, but the main MLA query/key projections (q_b_proj, kv_b_proj) used for the attention dot product have no RMSNorm/LayerNorm applied to them, and vision QK-norm is out of scope, leaving the language-model attention path itself without clear QK normalization. |
| Partial RoPE | not in its code | not stated | qk_rope_head_dim is 0 and mla_use_nope is true, and the config's validate_architecture raises if qk_rope_head_dim > 0, so the decoupled RoPE key is disabled; text decoder layers pass position_embeddings=None (NoPE) rather than partial RoPE. text_config.qk_rope_head_dim = 0text_config.mla_use_nope = true |
| YaRN RoPE scaling | not in its code | not stated | There is no rope_scaling or rope_parameters key of type yarn in text_config, and no YaRN scaling code is applied to the language model (rope is disabled entirely, qk_rope_head_dim=0). text_config.qk_rope_head_dim = 0 |
| Layers without positional encoding (NoPE) code only | in its code | not stated | All softmax-attention (MLA/deepseek_sparse_attention) layers apply no positional encoding at all (qk_rope_head_dim=0, mla_use_nope=true, and the model forward passes position_embeddings=None for every layer), which is a fixed NoPE choice rather than a mix of RoPE/no-RoPE layers, but it does mean the attention layers apply no rotary; since it's uniform across all attention layers (not some layers with and some without), this is effectively a fully NoPE model rather than the interleaved NoPE pattern described. text_config.mla_use_nope = truetext_config.qk_rope_head_dim = 0 |
| Mixture of experts | in its code | core | Glm5NextTextMoE routes each token to num_experts_per_tok=8 of n_routed_experts=288 expert MLPs via a learned sigmoid router (Glm5NextTextTopkRouter) in sparse mlp_layer_types layers. text_config.n_routed_experts = 288text_config.num_experts_per_tok = 8 |
| Shared expert code only | in its code | not stated | Glm5NextTextMoE adds a shared_experts MLP (sized by moe_intermediate_size * n_shared_experts=1) that every token passes through in addition to routed experts. text_config.n_shared_experts = 1 |
| Auxiliary-loss-free load balancing (selection bias) code only | in its code | not stated | The router adds e_score_correction_bias to sigmoid scores solely for top-k expert selection (topk_method noaux_tc), matching DeepSeek-V3's bias-based load balancing. text_config.topk_method = "noaux_tc" |
| Multi-token prediction layers code only | in its code | not stated | num_nextn_predict_layers=1 declares an MTP module, and the quantization_config lists model.layers.45.* weights (eh_proj, enorm, hnorm, shared_head) corresponding to the extra next-token-prediction layer beyond the 45 main layers. text_config.num_nextn_predict_layers = 1 |
| SwiGLU feed-forward code only | in its code | not stated | Both the dense Glm5NextTextMLP and the MoE Glm5NextTextExperts compute silu(gate(x)) * up(x) (clamped SwiGLU) with hidden_act set to silu. text_config.hidden_act = "silu" |
model architecture 8
token mixer 4
linear attention & state space 1
gated delta network 1
hybrid layer stacking 1
channel mixer 2
normalization & residual 1
multimodal architecture 1
data curation 1
tokenization 1
inference & serving 15
decoding strategy 1
reasoning control 4
inference quantization 3
serving parallelism 4
inference kernel 1
agentic scaffolding 2
software implementation 1
infrastructure service 1
evaluation 2
unfiled 6
Further reading
Picked by hand, not extracted: where to read more, not evidence for anything on this page.
- GLM-5.3-Flash architecture card — LLM Architecture Gallery explainer sebastianraschka.com
Sources
The curated document list for this model. "not fetched" means the URL is recorded but its text was not read in the current run.
| Document | Kind | Publisher | Status |
|---|---|---|---|
| z.ai/blog/glm-5.3-flash | official blog | Z.ai | not fetched |
| arxiv.org/abs/2602.15763 | technical report | GLM-5 Team | read |
| huggingface.co/zai-org/GLM-5.3-Flash | model card | Z.ai | read |
| github.com/zai-org/GLM-5 | code repo | Z.ai | read |
| docs.z.ai/guides/llm/glm-5.3-flash | vendor docs | Z.ai | read |
| recipes.vllm.ai/zai-org/GLM-5.3-Flash | vendor docs | vLLM | read |
| marktechpost.com/2026/08/26/z-ai-releases-glm-5-3-flash-a-320b-a18b-nat… | news | MarkTechPost | read |
| openrouter.ai/z-ai/glm-5.3-flash | vendor docs | OpenRouter | read |