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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

The offer takes effect at 10:00 on October 4, 2026 (SGT, UTC+8).

From that time, eligible GLM-5.3-Flash usage through B.AI API and Chat is billed at 70% of the standard reference price.

The pricing table below continues to show standard reference prices.

Limited-Time Discount70% from Oct 4, 10:00 SGT

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, and max reasoning effort, with max as 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​

CapabilityDescription
ReasoningThinking is always enabled. reasoning_effort supports low, high, and max; the default is max.
Creative WritingSupports general and long-form text generation.
CodingZ.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.
MultimodalAccepts text, image, video, and file input and produces text output.
Context Window1,000,000 tokens.
Max Output131,072 tokens; the default max_tokens value is 65,536.
Tool UseSupports 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.
MultilingualThe official model repository identifies English and Chinese support.

Known Limitations​

  • thinking.type only supports enabled; applications that require lighter reasoning should use reasoning_effort: "low" rather than disabling thinking.

Standard Pricing​

The token prices below are shown in USD per 1 million tokens; web search is billed in USD per use.

ModelInput
(USD / 1M Tokens)		Cache Write
(USD / 1M Tokens)		Cache Read
(USD / 1M Tokens)		Output
(USD / 1M Tokens)		Web Search
(USD / use)
GLM-5.3-Flash$0.15$0.15$0.03$0.50-

Credits settlement: B.AI converts charges at 1 USD = 1,000,000 Credits and deducts Credits from the account balance.

Standard price effective date: The prices above take effect at 00:00 on September 10, 2026 (UTC+8). This standard price update does not affect current promotions. During a promotion, billing follows the applicable promotion rules; after it ends, the standard reference prices above apply.

Pricing note

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.