OpenAI's AI coding agent can run software engineering tasks (coding, bug fixing, refactoring) independently in a cloud environment, supporting CLI, web, desktop app, and IDE integration (VS Code, JetBrains, Xcode)
Free Version Limitations
A free ChatGPT account can use Codex, but with Limited access; the CLI version can be used with your own API key, and the fee is based on API usage.
Long-form writing and document quality are its strengths, with the paid version including the Claude Code engineering tool
FreeThe quota is calculated based on a rolling 5-hour usage window (not simply resetting at a fixed number every day), and general conversations can be used for around 10-20 times, excluding Claude Code.
AI code editors are a staple in the engineering community
FreeHobby: 2000 times of completion + 50 times of slow progress requests (confirmed on the official website on 2026-07-26, but the official website no longer lists these numbers in detail, only mentioning limited quota, and the specific numbers are now only seen in third-party community sources, keeping the record but adjusting the confidence level to medium)
The most popular AI completion tools have a hidden benefit of being free for students
FreeThe general user free tier includes 2,000 completions and 50 chats per month. Open-source maintainers and teachers can upgrade to Pro for free. The free student plan has reopened for new applications since 2026-06-17, after being suspended since 2026-04-20 for 58 days. As of 2026-07-27, the model selection for Free and Student plans has been limited to only Auto, and manual model specification is no longer available, while Pro and above plans are not affected.
Launched in May 2025 and continuously updated rapidly in 2026. Features: cloud-based parallel execution of multiple tasks, built-in worktree, and integratable with ChatGPT. Free version is available but has a quota limit.
