GPT-5.1 Codex Max
GPT-5.1 Codex Max on Zumik: live pricing, context, and caching, routable by id or alias through one OpenAI-compatible endpoint.
At a glance.
| Provider | OpenAI |
| Family | gpt-5 |
| Released | 2025-11 |
| License | Proprietary |
| Context window | 400K tokens |
| Max output | 128K tokens |
| Modalities | text, image |
| Tool calling | Yes |
| Reasoning mode | Yes |
| Caching | automatic |
| Batch discount | 50% off |
What reuse looks like here.
Pricing, context, and capabilities for GPT-5.1 Codex Max are live, but it is outside the flagship set Zumik benchmarks in depth, so measured reuse, capture, and warm TTFT are not shown yet. Run a workload estimate or route it by id to start collecting traces.
What you actually pay once caching works.
At a typical 55% prefix reuse, a million input tokens on GPT-5.1 Codex Max effectively costs $0.63 instead of $1.25 - blending to roughly $2.97 with a 25% output share. Background work drops a further 50% on the batch tier.
Estimate it for your workloadRoute it directly by id, or let an alias pick it when it wins under policy.
Same OpenAI client, this model.
from openai import OpenAI
client = OpenAI(base_url="https://api.zumik.ai/v1", api_key="zk_live_...")
r = client.responses.create(
model="gpt-5-1-codex-max",
input="Draft a fix for the failing test.",
)
print(r.usage.input_tokens_cached) # confirm reuseGPT-5.1 Codex Max, answered.
How much does GPT-5.1 Codex Max cost?
GPT-5.1 Codex Max is $1.25 per million input tokens and $10.00 per million output tokens through Zumik. Cache reads are $0.13 per million, a 90% discount on input.
What is GPT-5.1 Codex Max's context window?
GPT-5.1 Codex Max supports a 400K-token context window with up to 128K output tokens.
Run GPT-5.1 Codex Max with reuse measured.
Point an OpenAI client at Zumik and see exactly how much of this model's input you are reusing.