OpenAI: GPT-5.1-Codex-Mini vs Z.ai: GLM 4.5V
A side-by-side comparison of OpenAI: GPT-5.1-Codex-Mini ($0.88 / 1M tokens) and Z.ai: GLM 4.5V ($2.10 / 1M tokens) using current USD prices and capabilities from the api14 catalog. Both run through the same OpenAI-compatible API.
Specifications
| OpenAI: GPT-5.1-Codex-Mini | Z.ai: GLM 4.5V | |
|---|---|---|
| Provider | OpenAI | Z.ai |
| Input | $0.88 / 1M tokens | $2.10 / 1M tokens |
| Output | $7.00 / 1M tokens | $6.30 / 1M tokens |
| Cache read | $0.11 / 1M tokens | $0.39 / 1M tokens |
| Web search | $35.00 / 1K searches | - |
| Context window | 400,000 | 65,536 |
| Max output | 128,000 | 16,384 |
| Input | image, text | text, image |
| Output | text | text |
| Tool calling | ||
| Structured output | ||
| Reasoning control | ||
| Added | Nov 13, 2025 | Aug 11, 2025 |
Key differences
- OpenAI: GPT-5.1-Codex-Mini is 58% cheaper on input tokens.
- Z.ai: GLM 4.5V is 10% cheaper on output tokens.
- OpenAI: GPT-5.1-Codex-Mini reads 6.1× more context (400,000 tokens).
- Only OpenAI: GPT-5.1-Codex-Mini supports structured JSON output.
- A request with 1,000 input and 500 output tokens costs $0.00438 with OpenAI: GPT-5.1-Codex-Mini and $0.00525 with Z.ai: GLM 4.5V.
In depth
OpenAI: GPT-5.1-Codex-Mini is made by OpenAI and is positioned as a compact member of the Codex family, released on 2025-11-13. Z.ai: GLM 4.5V is made by Z.ai and was released earlier, on 2025-08-11. Both are text output models, so whatever you send them comes back as text, and both accept images alongside text as input. The practical difference starts with who maintains them and which API surface you prefer, since both are reachable through the same gateway here.
The clearest split is context. GPT-5.1-Codex-Mini offers a 400000 token context window, while GLM 4.5V offers 65536 tokens, so the OpenAI model can hold far more material in a single call. Both take image and text input and both return text, so multimodality is not a differentiator between them. On parameters, GPT-5.1-Codex-Mini exposes reasoning controls such as reasoning_effort, verbosity, include_reasoning, structured_outputs and max_completion_tokens, while GLM 4.5V exposes sampling controls such as temperature, top_p, top_k, frequency_penalty, presence_penalty and repetition_penalty. Structured outputs are listed only for GPT-5.1-Codex-Mini, so if you need schema constrained responses, that is the side to use. Tool calling appears on both, so neither has an exclusive advantage there, and reasoning support is not a meaningful differentiator based on what is listed.
For day to day selection, reach for GPT-5.1-Codex-Mini when the job involves large inputs, long files, big diffs, or multi document context, and when you want structured outputs or fine grained reasoning effort control. Reach for GLM 4.5V when the task fits comfortably inside a smaller context and you want direct control over sampling behaviour, for example tuning temperature, top_p or penalties for creative or stylistic variation. Cost matters too: GPT-5.1-Codex-Mini is the cheaper side for input, while GLM 4.5V is the cheaper side for output, so workloads dominated by long prompts lean one way and workloads dominated by long generations lean the other. Check the live price table for the actual numbers before committing.
Calling either model through api14 works the same way because the API is OpenAI compatible. You point your client at the gateway, send a chat completions request, and change only the model id. Use "openai/gpt-5.1-codex-mini" for the OpenAI model and "z-ai/glm-4.5v" for the Z.ai model. Your messages array, image parts, tool definitions and response handling stay identical, so switching is a one line change and you can compare behaviour on your own workload without rewriting integration code.
There are still cases where the other model wins. If your prompts are short and your outputs are long, GLM 4.5V is the cheaper output side and its sampling parameters give you more direct control over generation style. If you need a very large context, structured outputs, or reasoning effort settings, GPT-5.1-Codex-Mini is the better fit.
Switch with one string
Both models use the same endpoint and request shape. Change the model value from "openai/gpt-5.1-codex-mini" to "z-ai/glm-4.5v" and prompts, streaming and tools keep working.
import OpenAI from "openai";
const client = new OpenAI({
baseURL: "https://api14.com/api/v1",
apiKey: process.env.API14_API_KEY,
});
const result = await client.chat.completions.create({
"model": "z-ai/glm-4.5v",
"messages": [
{
"role": "user",
"content": "Explain vector databases in two sentences."
}
]
});
console.log(result.choices[0].message.content);
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