OpenAI Codex · a cloud software-engineering agent

Codex runs each task in its own isolated, sandboxed cloud environment preloaded with your repository. It reads and edits files and runs commands (tests, linters, type checkers), then proposes a pull request you review.

1
Assign a task
A natural-language issue, in your repo.
2
Spin up a sandbox
Isolated container, repo preloaded, network off.
3
Edit and run
Change files, run the test suite in a terminal.
4
Iterate to green
Read the failure, fix, re-run until tests pass.
5
Propose a PR
Open a pull request, citing terminal logs.
codex
# user assigns a task
task> Fix jdiff error with special characters in filenames
repo: codex-cli branch: main
Code ▶
# a fresh, isolated environment is created
✓ clone repository into /workspace
✓ install dependencies (cached)
✓ load AGENTS.md, setup script
⊘ network access: DISABLED at execution
# edit files, then run the suite
- execSync(`git diff`, { shell: true })
+ execFileSync('git', ['diff'], { shell: false })
+ test('handles filenames with quotes', ...)
$ pnpm test tests/get-diff.test.ts
$ pnpm test (run 1)
✗ 1 failed · get-diff: special characters
→ read traceback, adjust escaping
$ pnpm test (run 2)
✓ 31 passed · 0 failed (4m 28s)
# human reviews the proposed change
Fix jdiff error with special characters
2 files changed  +46 −11
✓ evidence: tests 31 passed, terminal logs attached
Open pull request
Click to walk through one Codex task, from prompt to reviewed pull request.
OpenAI, "Introducing Codex", May 2025. Powered by codex-1, a version of o3 trained with RL on real coding tasks.