OpenAI Launches Codex: Its Most Advanced AI Coding Agent
OpenAI announced on Friday the launch of a research preview of Codex, its most capable AI coding agent to date.
What Powers Codex?
Codex is powered by codex-1, a variant of OpenAI’s o3 model optimized for software engineering tasks. OpenAI says codex-1:
Produces cleaner code than o3
Follows instructions more precisely
Iteratively tests code until results are successful
How Codex Works
The agent operates in a cloud-based, sandboxed virtual environment. It can preload your GitHub repositories, allowing it to:
Write features
Fix bugs
Answer codebase questions
Run tests
Tasks may take anywhere from 1 to 30 minutes, and Codex can handle multiple tasks simultaneously without restricting user access to their computer or browser.
Access and Pricing
Codex is available now for ChatGPT Pro, Enterprise, and Team users. Initially, users will get generous access, but rate limits will roll out in the coming weeks. Users can purchase additional credits once limits are enforced. OpenAI plans to expand access to ChatGPT Plus and Edu users soon.
AI Coding Tools Are Booming
AI coding assistants, or “vibe coders,” are becoming popular. Google and Microsoft claim that ~30% of their code is written by AI. In 2024:
Anthropic launched Claude Code
Google updated Gemini Code Assist with new capabilities
Popular AI tool Cursor reached $300M in annualized revenue and may raise funds at a $9B valuation. OpenAI recently acquired Windsurf, the team behind another coding tool, for $3B.
Using Codex
Codex appears in the ChatGPT sidebar. Users can:
Assign tasks via a prompt and click “Code”
Ask questions with the “Ask” button
Assigned tasks appear below for progress tracking.
Safety and Limitations
According to OpenAI’s Agents Research Lead, Josh Tobin, the long-term goal is to make Codex a “virtual teammate” that autonomously completes tasks in hours that would take engineers days.
Codex will:
Refuse requests to generate malicious software
Operate in an air-gapped environment with no internet or external API access
Open Source and API
OpenAI is also updating Codex CLI, its open-source terminal agent, with the o4-mini model. Pricing for the API:
$1.50 per 1M input tokens (~750,000 words)
$6 per 1M output tokens
Part of ChatGPT’s Bigger Picture
Codex joins OpenAI’s growing suite of tools within ChatGPT, including:
Sora (video platform)
Deep Research
Operator (web browsing agent)
These tools aim to add value for subscribers and encourage upgrades through added capabilities and paid tiers.