OpenAI: GPT-5.3-Codex

deprecatedproprietary

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.

Intelligence
Reasoning
Speed
Context
400K
Max output
128K
Input price
$1.75/1M tokens
Output price
$14/1M tokens

Capabilities

Reasoning & Interaction
Reasoning
Tool Calling
Output Control
Structured Output
JSON Mode
Infrastructure
Streaming

Details

Model IDopenai/gpt-5.3-codex
Provider OpenRouter
Creator OpenAI
Familygpt-5.3
Licenseproprietary
Statusdeprecated
Typechat
Input modalitiestext, image
Output modalitiestext
Open weightNo
Parameters—
Architecture—
Context window400K tokens
Max input272K tokens
Max output128K tokens
Reasoning tokensYes
Knowledge cutoff
Release date
Deprecation date
Sourceofficial

Tools

Function Callingfunction_calling
Call external functions and APIs

Pricing

Input
$1.75
Output
$14
Cache write
—
Cache read
$0.18
Batch in
—
Batch out
—

Family Comparison: gpt-5.3

ModelContextMax outPricing
OpenAI: GPT-5.3 Chat128K16K$1.75$14
OpenAI: GPT-5.3-Codex400K128K$1.75$14

API

GET/v1/models/openrouter/openai/gpt-5.3-codex

OpenAI: GPT-5.3-Codex

deprecated
openai/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.

Changes · 3 entries
openai/gpt-5.3-codexupdate1cd659eMar 24, 2026, 04:19 AM
capabilitiesjson modeyes
openai/gpt-5.3-codexupdate2b100acMar 23, 2026, 05:30 AM
model_typechat
release_date2026-02-24
taglineGPT-5.3-Codex is OpenAI’s most advanced agentic coding mo...
tools["function_calling"]
openai/gpt-5.3-codexcreate7f5c66fMar 21, 2026, 05:16 AM