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Z AI releases proprietary GLM-5.3-Flash reasoning model

The new text-based model features a 400,000-token context window and competitive pricing for its benchmark performance.

The short version

  • Z AI launched GLM-5.3-Flash, a proprietary text-only reasoning model, on August 26, 2026.
  • The model scored 57 on the Artificial Analysis Intelligence Index, outperforming the median score of 18 for similarly priced models.
  • API pricing is set at $0.15 per million input tokens and $0.50 per million output tokens, with a 400,000-token context window.

Key facts

  • Z AI released the proprietary GLM-5.3-Flash AI reasoning model on August 26, 2026.[Hacker News]
  • GLM-5.3-Flash scored 57 on the Artificial Analysis Intelligence Index, compared to a median score of 18 among models in the same price tier.[Hacker News]
  • Z AI set API pricing for the model at $0.15 per 1 million input tokens and $0.50 per 1 million output tokens.[Hacker News]
  • The model features a 400,000-token context window and only supports text inputs and outputs.[Hacker News]
  • GLM-5.3-Flash generated 150 million output tokens during its Artificial Analysis benchmark run, costing $138.02 total.[Hacker News]

What remains uncertain

  • Z AI has not publicly disclosed the exact parameter count or model size of GLM-5.3-Flash.[Hacker News]

Sources