GLM-5.3-Flash
Overview
GLM-5.3-Flash is an open-weight, natively multimodal model released by Z.AI on August 26, 2026 as the Flash-tier member of the GLM-5 family. It combines 320 billion total parameters with 18 billion activated parameters, a 1M-token context window, and a hybrid sparse-and-linear-attention architecture for coding, agentic, and visual knowledge-work workloads.
GLM-5.3-Flash
- API: GLM-5.3-Flash API usage is currently billed at
0 Credits. No input, cache write, cache read, or output token fees apply. - Chat: Free access begins when GLM-5.3-Flash becomes available in B.AI Chat. The availability time is subject to the actual model listing. Once available, Chat usage is billed at
0 Credits.
After the offer ends, GLM-5.3-Flash will return to the prices shown on this page.
Key Features
- Efficient Hybrid Architecture: Uses sparse attention, linear attention, Manifold-Constrained Hyper-Connections (mHC), and IndexPool. Z.AI reports 3.0x lower attention compute and 4.4x smaller KV-cache size than GLM-5.3 in its architecture comparison.
- Native Multimodal Understanding: Accepts text, images, videos, and files, allowing agents to inspect interfaces, rendered outputs, documents, and other visual evidence during a task.
- Coding and Agent Evaluation: Z.AI reports 84.3 on Terminal-Bench 2.1, 63.4 on DeepSWE v1.1, 78.4 on Toolathlon Verified, and 48.8 on AutomationBench v1.0.6.
- Configurable Always-On Reasoning: Supports
low,high, andmaxreasoning effort, withmaxas the default. Thinking cannot be disabled.
Best Use Cases
- Visual Software Engineering: Building and refining frontends, games, 3D scenes, and other interfaces by combining code changes with screenshot or rendered-output inspection.
- Long-Horizon Coding Agents: Repository-scale implementation, debugging, testing, and multi-step automation that require reasoning, function calls, and large working contexts.
- Multimodal Professional Workflows: Extracting and reasoning over documents, charts, dashboards, presentations, spreadsheets, and video before producing structured text or office deliverables through an agent environment.
- Cost-Sensitive API Workloads: High-volume text and multimodal tasks that benefit from low per-token pricing, cached-input discounts, and a 1M-token context window.
Capabilities and Limitations
| Capability | Description |
|---|---|
| Reasoning | Thinking is always enabled. reasoning_effort supports low, high, and max; the default is max. |
| Creative Writing | Supports general and long-form text generation. |
| Coding | Z.AI reports Terminal-Bench 2.1: 84.3, DeepSWE v1.1: 63.4, NL2Repo: 56.3, Toolathlon Verified: 78.4, and AutomationBench v1.0.6: 48.8. |
| Multimodal | Accepts text, image, video, and file input and produces text output. |
| Context Window | 1,000,000 tokens. |
| Max Output | 131,072 tokens; the default max_tokens value is 65,536. |
| Tool Use | Supports function calling, streamed tool calls, context caching, and JSON structured output. ZCode can pair the model with Browser Use and Computer Use for visually grounded agent workflows. |
| Multilingual | The official model repository identifies English and Chinese support. |
Known Limitations
thinking.typeonly supportsenabled; applications that require lighter reasoning should usereasoning_effort: "low"rather than disabling thinking.
Credits Usage
| Model | Input (Credits/Token) | Cache Write (Credits/Token) | Cache Read (Credits/Token) | Output (Credits/Token) | Web Search (Credits/Use) |
|---|---|---|---|---|---|
| GLM-5.3-Flash | 0.075 | 0.075 | 0.015 | 0.25 | - |
Limited-time pricing: The 50% token-price promotion ends at 24:00 on September 9, 2026 (UTC+8, Singapore time).
Prices shown in the documentation are B.AI standard reference prices for base billing purposes. B.AI may provide lower actual usage costs through limited-time offers, top-up bonuses, and account benefits. Specific prices, bonus Credits, account benefits, and final billing are subject to the platform display and billing records.