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Facts checked against both vendors on September 28, 2026.
Codex is the better pick if you already pay for ChatGPT and want one subscription to cover a terminal agent, an IDE extension, cloud tasks and pull request review on OpenAI models. Copilot is the better pick if your team lives on GitHub, wants to choose between Claude, GPT, Gemini and Grok, and needs per-seat billing an admin can manage. The decision often comes down to whether you want a ChatGPT plan or a GitHub plan.
An AI system by OpenAI that translates natural language to code.
OpenAI Codex and GitHub Copilot both started as autocomplete and have both grown into agents that take a task, work through a repository and open a pull request. Each now has a CLI, an IDE extension, a cloud execution mode and an automated reviewer. The differences that matter to a buyer are which models you get, how usage is metered, and which platform the product is anchored to.
Codex is anchored to ChatGPT: access comes with a ChatGPT subscription, limits are messages per five-hour window, and the models are OpenAI's. Copilot is anchored to GitHub: access is a plan or seat, limits are monthly AI credits, and the model list spans several vendors.
Codex is OpenAI's coding agent. Its documentation says it runs in the ChatGPT desktop app, on the web, as a CLI, as an IDE extension, in a cloud environment and through a GitHub integration. The CLI lets you set permissions per run so you "choose when Codex can edit files or run commands without asking," and a /model command switches models and reasoning effort. Codex cloud runs tasks in isolated environments in parallel, connects to GitHub or GitLab (beta), and can be started from GitHub pull requests, GitLab merge requests, Linear issues or Slack threads. The GitHub integration reviews every pull request automatically or on an @codex review comment, and a follow-up such as @codex fix the P1 issue starts a cloud chat that can push a fix to the branch. Review rules live in a Code Review Rules section of AGENTS.md.
GitHub Copilot is GitHub's assistant and agent. Its documentation splits it into assistive features (suggesting, answering, explaining) and agentic ones where Copilot "researches a repository, proposes a plan, edits files, reviews pull requests, runs tools, and prepares tasks for your review." The cloud agent runs in an ephemeral GitHub Actions environment, takes work from Issues, the agents panel, VS Code or an @copilot comment, and opens pull requests. Code review runs on pull requests, can be enforced by repository rulesets, and reads instructions from the .github directory. The plan page lists Claude, GPT, Gemini and Grok models.
Codex has no separate price list; it comes with ChatGPT plans. OpenAI's pricing page lists Free at $0, Go at $8 per month, Plus at $20 per month, Pro from $100 per month with 5x or 20x the Plus rate limits, Business at $20 per user per month on annual billing (two or more users) or $25 monthly, and Enterprise on custom pricing. Free and Go get Codex in the desktop app; Plus adds the web, CLI, IDE extension and cloud integrations. Limits are local messages per five-hour window: on Plus, OpenAI lists 350 to 3,000 for GPT-6 Luna, 15 to 150 for GPT-6 Sol and 5 to 45 for GPT-6 Astra. You can buy credits when you run out, or bill Codex against an API key at API rates.
Copilot meters usage in AI credits worth $0.01 each. GitHub's plans documentation lists Free at $0 with 2,000 completions and limited chat and agent use, Pro at $10 per month with 1,500 monthly credits, Pro+ at $39 with 7,000 credits and Max at $100 with 20,000 credits. Copilot Business is $19 per seat per month with 1,900 credits per user and Enterprise is $39 per seat with 3,900 credits per user; usage beyond the pool is $0.01 per credit. GitHub estimates a code review consumes $0.05 to $1 worth of credits at Lite effort and $0.25 to $5 at Balanced. The cloud agent uses Actions minutes and credits but has no separate fee.
Codex is the stronger choice for long, autonomous work. Its cloud mode gives "longer tasks dedicated environments" that continue while you do something else, and entry points from Linear and Slack let non-engineers kick off work without opening an editor. If your team already has ChatGPT Plus or Business, Codex arrives at no extra cost, and the five-hour windows are generous for the lighter Luna model.
The review loop is tighter: a finding becomes a fix with one comment on the pull request, and a security review preview goes deeper on security-specific risks. The CLI's explicit permission model with a visible sandbox suits developers who want an agent with guardrails.
Copilot wins on model choice and administration. You can pick Claude, GPT, Gemini or Grok per task, and Pro+ and above can delegate to third-party coding agents. For a company, Business and Enterprise give an admin a seat count, a credit pool and policy controls inside the GitHub organization it already manages, which is simpler than issuing ChatGPT Business seats to engineers.
The cloud agent runs on GitHub Actions in your repository's environment, so it executes your tests and linters as part of the task, and its output is an ordinary pull request. Code review can be made mandatory through rulesets, and the Free plan gives a solo developer 2,000 completions, agent mode and the CLI at no cost.
Pick Codex if you are an individual or small team already on ChatGPT, you want to hand multi-hour tasks to a cloud agent, and you are happy to standardize on OpenAI models. It also fits teams that trigger work from Linear or Slack.
Pick Copilot if your organization runs on GitHub, you want admins to control seats and spend from the GitHub side, you want a choice of model vendors, or you need review enforced by repository rules. GitLab teams should note that Codex cloud supports GitLab in beta while Copilot is a GitHub product.
Built from each tool's listing. Vendors can update their own listing after claiming it.
Included with ChatGPT plans: Free ($0), Go ($8 per month), Plus ($20 per month), Pro (from $100 per month), Business ($20 per user per month billed annually or $25 monthly) and Enterprise (custom). Limits are counted per five-hour window and Codex can also be billed against an API key.
Free ($0), Pro ($10 per month, 1,500 AI credits), Pro+ ($39, 7,000 credits), Max ($100, 20,000 credits), Business ($19 per seat per month, 1,900 credits per user) and Enterprise ($39 per seat, 3,900 credits per user). Overage is $0.01 per credit.
