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OpenAI Responses

gpt-5.3-codex

GPT-5.3-Codex is OpenAI’s most advanced agentic coding model, combining the frontier software engineering performance of GPT-5.2-Codex with the broader reasoning and professional knowledge capabilities of GPT-5.2.

👁Vision🧠Reasoning🔧Tool calling⚡Caching
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Specifications

Context window400K tokens
Max output128K tokens
API typechat
AddedFeb 25, 2026
Model IDopenai-responses/gpt-5.3-codex
Data retentionYes (30 days)
Used for trainingNo
Provider location🇺🇸 US
Privacy policyOpenAI Privacy Policy→

Benchmarks

Benchmarks haven't been published yet for this exact variant.

Some variants (region-specific deployments, highspeed tiers) share benchmarks with their base model — check the base model page or the OpenAI Responses models overview.

Pricing

Input / 1M
$1.75
Output / 1M
$14.00
Cache write / 1M
$14.00
Cache read / 1M
$0.17
Estimated cost
100K input + 10K output$0.31
1M input + 100K output$3.15
10M input + 1M output$31.50

Requesty charges exactly what the upstream provider charges — no markup, no per-request fees. Prompt caching and smart routing can reduce effective cost by 30-80%.

Quickstart

Drop-in compatible with the OpenAI SDK. Change the base URL, swap in your Requesty API key, and set the model to openai-responses/gpt-5.3-codex.

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from openai import OpenAI

client = OpenAI(
    api_key="YOUR_REQUESTY_API_KEY",
    base_url="https://router.requesty.ai/v1",
)

response = client.chat.completions.create(
    model="openai-responses/gpt-5.3-codex",
    messages=[
        {"role": "user", "content": "Explain quantum computing in one paragraph."},
    ],
)

print(response.choices[0].message.content)

Other OpenAI Responses models

gpt-5.5
1.1M ctx$5.00/1M
gpt-5.5-pro
1.1M ctx$30.00/1M
gpt-5.3-chat
128K ctx$1.75/1M
gpt-5.4-nano
400K ctx$0.20/1M
gpt-5.4-mini
400K ctx$0.75/1M
gpt-5.4
1.1M ctx$2.50/1M
SWE-Bench 82%

Frequently asked questions

How much does gpt-5.3-codex cost?
gpt-5.3-codex is priced at $1.75 per million input tokens and $14.00 per million output tokens when accessed via Requesty. Prompt caching is supported, which can cut effective input cost by up to 90% on repeated context. Requesty charges exactly what the upstream provider charges — we don't add markup.
What is the context window of gpt-5.3-codex?
gpt-5.3-codex has a context window of 400K tokens, with a maximum output of 128K tokens per response. That's roughly 533 words of input you can fit in a single prompt.
What can gpt-5.3-codex do?
gpt-5.3-codex supports vision input, tool calling, extended reasoning, prompt caching. You can call it through any OpenAI-compatible client by pointing base_url to Requesty.
How do I use gpt-5.3-codex with the OpenAI SDK?
Install the OpenAI SDK, set base_url to "https://router.requesty.ai/v1", set your API key to your Requesty key, and set the model to "openai-responses/gpt-5.3-codex". The Quickstart above shows Python, JavaScript and cURL snippets.

Access gpt-5.3-codex through Requesty

One API key, 400+ models, OpenAI-compatible. No markup on provider prices, automatic failover, and smart caching built-in.

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