GLM-5.3 API Pricing: How Z.AI’s New Open-Weight Model Compares With Frontier AI Models

Following its high-profile debut with advanced coding and agent capabilities, Chinese AI startup Z.AI has made its new frontier open-weight language model, GLM-5.3, available through its application programming interfaces (APIs). Developers can access the GLM-5.3 API here.

The API allows developers to build applications, coding tools and autonomous agents on top of GLM-5.3. Teams can also integrate the model into existing workflows using OpenAI Chat Completions-compatible protocols.

Developers subscribed to the GLM Coding Plan currently have access through OpenAI-compatible interfaces. Z.AI has also said it plans to release the model weights, although the company has not yet announced a specific release date or licensing terms.

GLM-5.3 API pricing

Z.AI is keeping GLM-5.3 API pricing at the same level as GLM-5.2. The model costs $1.40 per million input tokens and $4.40 per million output tokens. Cached input is priced at $0.26 per million tokens, while Z.AI currently lists cached-input storage as free for a limited time.

This means developers can upgrade to the newer model without paying a higher per-token rate. Z.AI says GLM-5.3 delivers stronger coding performance and improved long-term agent capabilities, while remaining considerably less expensive than many premium frontier AI APIs.

GLM-5.3 pricing compared with other AI models

How much does GLM-5.3 cost compared with leading AI APIs?

Using a simple comparison of 1 million input tokens and 1 million output tokens, GLM-5.3 costs approximately $5.80. By comparison, Grok 4.6 costs $8 under its lower-context pricing tier, Kimi K3 costs $18, Claude Opus 5 costs $30, and GPT-5.6 Sol costs $35.

This comparison is intended to show relative API pricing rather than estimate the cost of a specific workload. Actual billing depends on the ratio of input to output tokens, cached-token usage, context length and total consumption.

Is GLM-5.3 the cheapest AI model?

GLM-5.3 is not the least expensive capable model in the comparison. Google’s introductory Gemini 3.7 Flash pricing is $0.75 per million input tokens and $3.75 per million output tokens through December 31, 2026. OpenAI’s GPT-5.6 Luna is priced at $0.20 per million input tokens and $1.20 per million output tokens.

Even so, GLM-5.3 remains in a significantly lower pricing tier than several premium frontier models against which it is increasingly being benchmarked. That combination of performance, OpenAI-compatible access and comparatively low API costs could make it attractive to developers building coding assistants and long-running AI agents.

GLM-5.3 performance and intelligence benchmarks

The pricing comparison has gained additional relevance following new independent benchmark results. Artificial Analysis gave GLM-5.3 an Intelligence Index score of 60, tying Kimi K3 as the highest-scoring open-weight model in the comparison. The result is 7 points higher than GLM-5.2.

Artificial Analysis estimates that GLM-5.3 costs approximately $0.68 per Intelligence Index task, compared with about $0.44 for GLM-5.2, despite both models having the same listed API token prices.

This difference highlights an important consideration when evaluating AI API pricing: a flat per-token rate does not necessarily translate into a flat cost for completed workloads. If a model uses more tokens to complete a task, the total cost can increase even when its input and output rates remain unchanged.

What GLM-5.3 means for developers

For developers, the immediate change is straightforward. GLM-5.3 is now available through the Z.AI API at the same $1.40 input and $4.40 output price per million tokens as GLM-5.2.

That gives development teams another relatively affordable option for testing frontier-class coding, reasoning and autonomous-agent workloads. Before moving GLM-5.3 into production, teams should compare output quality, latency, context requirements, token usage and the model’s final licensing terms once Z.AI publishes the weights.