Install

GPT-5.3-Codex as a coding agent in your terminal

GPT-5.3-Codex by OpenAI, one of 250+ models you can use in Darce, the open source AI coding agent you can undo.

ModelGPT-5.3-Codex
VendorOpenAI
Model idopenai/gpt-5.3-codex
Context window400k tokens
Price per 1M tokens$1.75 input · $14.00 output (OpenRouter)
Can dotool calling · reads images · reasoning
CategoryCoding-tuned

Strengths

A GPT model tuned by OpenAI for coding work, from the Codex line.

OpenRouter's description:

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. It achieves state-of-the-art results...

Use GPT-5.3-Codex as a coding agent in your terminal

Start Darce in your project with GPT-5.3-Codex:

npm install -g darce-cli
darce --model openai/gpt-5.3-codex

Already in a session? Type /model openai/gpt-5.3-codex, or open the picker with Ctrl+P. Darce then reads your code, edits files and runs commands with GPT-5.3-Codex; risky commands ask first, and /undo reverses any change, including what shell commands did. No account yet? npx darce-cli lets you try it free. Which plan includes which models is on the pricing page.

Make it your default or a gear

In ~/.darcerc, set it as the starting model or add it to the gears you move between with Shift+↑ / Shift+↓ (see configuration):

{
  "router": { "default": "openai/gpt-5.3-codex" },
  "gears": ["qwen/qwen3-coder", "openai/gpt-5.3-codex"]
}

Compare it on your own code

Benchmarks rarely match your repository. Race GPT-5.3-Codex against two other models on a real task and keep the best diff:

/derby --models openai/gpt-5.3-codex,openai/gpt-6.1-sol,openai/gpt-6-sol fix the failing test

Read more about /derby and /swarm.

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Model data from OpenRouter, refreshed daily. Prices are OpenRouter's list rates and show relative cost; your Darce allowance is used in proportion to them.