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Z.ai: GLM 5.3 Flash
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Z.ai: GLM 5.3 Flash

Near-frontier coding and agentic performance at budget-tier pricing, with native vision input and a 1M-token context window.

Context window: 
1048576
M tokens
Output: 
131072
 tokens
Modality:
Text
Image
PDF
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GLM 5.3 Flash: Frontier-Class Coding Agents at Budget Cost GLM-5.3-Flash is Z.ai's cost-optimized, natively multimodal model in the GLM-5 series, released under the MIT License and previously previewed as the stealth model "Ox Alpha." It is a 320B-parameter Mixture-of-Experts design with roughly 18B active per token, sitting below the larger GLM-5.3 flagship. Its distinguishing trait is delivering coding and agentic benchmark scores that approach Claude Opus 4.8 at a small fraction of the cost. It fits best in high-volume, long-horizon coding agents and document-heavy workflows where token economics dominate. Start building with the GLM 5.3 Flash API on AnyAPI.ai

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Z.ai: GLM 5.3 Flash

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Answers to common questions about integrating and using this AI model via AnyAPI.ai

GLM-5.3-Flash is designed for high-volume coding agents and long-horizon, tool-using agent workflows. Z.ai-reported benchmarks put it near Claude Opus 4.8 on agentic coding (63.4 DeepSWE v1.1, 84.3 Terminal-Bench 2.1) at roughly a tenth of the cost, making token-intensive code review, repository automation and long-context document processing economically viable.

GLM-5.3-Flash supports a context window of 1,048,576 tokens, approximately 1 million. It uses a hybrid sparse-and-linear attention architecture that keeps long-context inference affordable rather than scaling cost linearly with input length, which is why it suits whole-repository and large-document workloads.

Not especially. Independent Artificial Analysis measurements put output speed around 49 tokens per second on the Z.ai endpoint, below the ~67 t/s median for comparable models, and the model is somewhat verbose. "Flash" describes its low price tier, not its latency. Third-party hosts vary widely, with some exceeding 200 t/s.

Yes. GLM-5.3-Flash is the first natively multimodal model in the GLM-5 series, accepting text and image input and returning text. It supports function calling via tools and tool_choice, and JSON output via response_format, though without strict JSON-schema enforcement.

Yes. GLM-5.3-Flash weights are published under the MIT License, one of the most permissive licenses, allowing commercial use, modification and redistribution. It is a 320B-parameter Mixture-of-Experts model with about 18B active per token. Self-hosting is possible but requires substantial GPU capacity given the multi-hundred-GiB checkpoint.