GPT-5.1 Codex Mini

by OpenAI

GPT-5.1 Codex Mini is a faster, more cost-efficient Codex variant that keeps the 272,000-token context window while favoring quick responses for interactive development. It handles code generation and analysis across tasks from single-function edits to multi-file refactoring. The variant fits development environments, continuous integration pipelines, and real-time code assistance where response speed matters and the model still needs to work with large codebases.

Key info

Input
Output
Features
Context window
272K
Max output
128K
Input price
$0.25 /1M
Output price
$2.00 /1M
  • EU residency available
  • Zero data retention via Enterprise
  • No training by default
  • GDPR DPA available

Available routes

GPT-5.1 Codex Mini runs on 1 route through the Opper gateway. Compare residency, ZDR, and training posture at a glance β€” full data-handling detail per route below.

ProviderRegionZero data retentionTrainingInputOutput
EUEnterpriseNo$0.25$2.00

Uptime and availability

GPT-5.1 Codex Mini runs on a single route through the Opper gateway today, so its availability is that provider's availability.

99.80%route uptime, last 30 days
Single route, no failover target within this model.

Name a second model in the same request and the gateway tries it on retriable errors, so a busy hour never has to reach your users. Set up a fallback chain.

Measured over the last 30 days from each provider's official status feed via StatusGator. Refreshed hourly. See uptime for every provider Opper monitors.

Data handling per route

Each route hosting GPT-5.1 Codex Mini has its own privacy posture, residency, and GDPR terms. Postures are maintained by Opper with a last-verification timestamp.

Azure β€” SwedenπŸ‡ΈπŸ‡ͺ

Zero data retention is available via Opper Enterprise contract. No training on customer data. EU; DPA available.

Zero data retention
Available via Opper Enterprise contract.
Training
No training on customer data.
Logging
Abuse monitoring (30-day retention)
Third-party access
None disclosed
GDPR DPA
DPA available
Transfer mechanism
Not applicable β€” data stays in EU

Benchmarks

Independent benchmark scores β€” composite indices for reasoning, coding, and math, plus individual eval scores where available.

Global rank#153 of 596 LLMs
TierStrong
Output speed0 tok/s
First token0.00s
Intelligence Index31.3
Math Index91.7
Reasoning & knowledge
MMLU-Pro
82%
GPQA Diamond
81%
Humanity's Last Exam
19%
Long-context reasoning
65%
Coding
LiveCodeBench
84%
SciCode
43%
Agentic & tool use
Terminal-Bench Hard
33%
τ²-Bench Telecom
63%
Math & instruction following
AIME 2025
92%
IFBench
68%

Get started

Call GPT-5.1 Codex Mini through the Opper gateway with one API key. Let your coding agent set it up, or call it directly β€” Opper is drop-in compatible with the OpenAI, Anthropic, and Google AI SDKs.

Set it up with your agent

Copy this and paste it into a coding agent like Claude Code, Cursor or Codex and it'll wire up Opper for you.

Or call it directly

import OpenAI from "openai";
const client = new OpenAI({
apiKey: process.env.OPPER_API_KEY,
baseURL: "https://api.opper.ai/v3/compat",
});
const completion = await client.chat.completions.create({
model: "azure/gpt-5.1-codex-mini",
messages: [{ role: "user", content: "Hello" }],
});
console.log(completion.choices[0].message.content);

Compare GPT-5.1 Codex Mini with…

Side-by-side on privacy, EU hosting, pricing, and benchmarks.

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