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OpenAI: GPT-5.1-Codex: AI model

GPT-5.1 Codex is an OpenAI model, a GPT-5.1 variant optimized for software engineering and coding workflows, with up to 400K-token context. Reachable from inside Iran through Hormouz.

Context window:
400,000 tokens
Input:
$1.25/1M tokens
Output:
$10/1M tokens
Type:
text, image
  • Vision
  • Tools
  • Streaming
  • Long context

Thinking levels: Always thinks · high · medium · low

GPT-5.1 Codex is a GPT-5.1 variant optimized for software engineering and coding workflows. GPT-5.1 Codex targets interactive development and long, independent execution of complex engineering tasks on the updated 5.1 stack. It supports a context window of up to 400K tokens, with training data through Sep 2024.

GPT-5.1 Codex is served through Hormouz behind an OpenAI-compatible API. It supports tool calling, image (vision) input and step-by-step reasoning. Point your base URL at Hormouz and drop in a Hormouz key, and existing OpenAI SDK code runs unchanged.

Pricing is usage-based: $1.25 per million input tokens and $10 per million output tokens. Hormouz provides stable access to the model from inside Iran, with no foreign credit card or circumvention tooling required.

GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks....

Quickstart

curl https://api.hormouz.net/v1/chat/completions \
  -H "Authorization: Bearer ng-YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.1-codex",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

Specs

VendorOpenAI
TypeText, Image
Context window400,000 tokens
Pricing$1.25/M in · $10.00/M out
APIChat Completions
CapabilitiesStreaming · Vision · Tools

Benchmarks

Reasoning

GPQA Diamond
Graduate-level scientific reasoning
86%
HLE
Humanity's Last Exam
25.7%
IFBench
Instruction-following
70%
AA-LCR
Long-context reasoning
69.3%
CritPt
Research-level physics reasoning
5.7%
AA Omniscience
Broad factual knowledge accuracy
39.9%
Non-Hallucination
Rate of avoiding fabricated answers
22.8%

Coding

Terminal-Bench Hard
Agentic coding & terminal use
34.8%

Agentic

τ²-Bench
Tool-use agents in dual-control scenarios
83%

Source: Artificial Analysis

Design Arena

How Design Arena works ↗

Ranking distribution

First
782
Second
822
Third
200
Fourth
127

1931 tournaments ?

Full-Stack
Top 70%
1,086Elo
Win rate: 44.5%
Mobile Apps
Top 41%
1,191Elo
Win rate: 53.4%
Web Apps
Top 98%
1,011Elo
Win rate: 44%
Code
Top 59%
1,158Elo
Win rate: 54.6%Avg time: 73.3s
Data Viz
Top 34%
1,222Elo
Win rate: 55.9%Avg time: 43.9s
Game Dev
Top 57%
1,151Elo
Win rate: 50.5%Avg time: 103s
UI Component
Top 29%
1,244Elo
Win rate: 60%Avg time: 70.2s
Website
Top 59%
1,168Elo
Win rate: 56.1%Avg time: 72.7s

Metrics sourced from Design Arena

Code example

cURL
curl https://api.hormouz.net/v1/chat/completions \
  -H "Authorization: Bearer ng-YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.1-codex",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'
Python
from openai import OpenAI
client = OpenAI(api_key="ng-YOUR_API_KEY", base_url="https://api.hormouz.net/v1")
response = client.chat.completions.create(
    model="openai/gpt-5.1-codex",
    messages=[{"role": "user", "content": "Hello!"}],
)
print(response.choices[0].message.content)
JavaScript
import OpenAI from "openai";
const client = new OpenAI({ apiKey: "ng-YOUR_API_KEY", baseURL: "https://api.hormouz.net/v1" });
const response = await client.chat.completions.create({
  model: "openai/gpt-5.1-codex",
  messages: [{ role: "user", content: "Hello!" }],
});
console.log(response.choices[0].message.content);

Buy the OpenAI: GPT-5.1-Codex API, paid in rial

  • Buy credit with an Iranian bank card; no foreign card or account needed.
  • One Hormouz key reaches OpenAI: GPT-5.1-Codex and 600+ other models, and you pay only for what you use.
  • No VPN and no risk of a banned account; just change the base URL to api.hormouz.net/v1.
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FAQ

How much does GPT-5.1 Codex cost?
Billing is usage-based: $1.25 per million input tokens and $10 per million output tokens. There is no fixed monthly fee. You pay only for what you use, and current rates are shown in the Hormouz dashboard.
How do I access GPT-5.1 Codex from inside Iran?
Create an account on Hormouz and generate an API key. Hormouz provides a stable path to GPT-5.1 Codex from inside Iran, with no foreign credit card or circumvention tooling required.
Is GPT-5.1 Codex compatible with OpenAI code?
Yes. Hormouz exposes an OpenAI-compatible API. Just change the base URL to Hormouz and swap in your Hormouz key. Your existing SDKs and chat-completions code run without a rewrite.
What context window and capabilities does GPT-5.1 Codex have?
GPT-5.1 Codex supports a context window of up to 400K tokens. It also supports tool calling, image (vision) input and step-by-step reasoning. That makes it a good fit for long documents, codebases and multi-turn conversations.
What is GPT-5.1 Codex good for?
GPT-5.1 Codex is purpose-built for coding and software engineering. Writing and refactoring code, agentic development runs, debugging and working across large codebases.
What is GPT-5.1 Codex's knowledge cutoff?
GPT-5.1 Codex's training data runs through Sep 2024. For information newer than that, provide the relevant context in your prompt or connect a tool that fetches live data.

Updated 2026-10-13