Codex (OpenAI)

A Tier · 8.3/10

OpenAI's cloud-based coding agent -- runs parallel tasks, proposes PRs, and lives inside ChatGPT

Last updated: 2026-04-13Free tier availablePowered by GPT-5.3-Codex / GPT-5.4

Score Breakdown

8.0

Ease of Use

8.0

Output Quality

8.0

Value

9.0

Features

Benchmark Scores

Benchmarks for GPT-5.3-Codex

Benchmark	Description	Score
SWE-bench	Real GitHub issue fixing	72%
HumanEval	Python code generation	95%

Last updated: 2026-04-13

Visit Codex (OpenAI)

The Good and the Bad

What we like

+Lives inside ChatGPT -- if you already pay for Plus ($20/mo), Codex is included at no extra cost
+Parallel task execution is a real differentiator -- assign 5 tasks at once and come back when they're done
+Code review feature catches bugs and suggests improvements before you merge -- genuinely useful, not just a gimmick
+Sandboxed environments per task means it can't break your local setup -- runs tests safely in the cloud
+GitHub integration lets it propose PRs directly, read your repo, and work on real issues end-to-end
+CLI, web, and IDE extension gives you three ways to interact depending on your workflow

What could be better

−Usage limits burn through fast -- 20-100 messages per 5 hours on Plus means heavy users hit the wall mid-task
−Can't be corrected mid-task -- once you send a prompt, you wait for the full result, no steering
−Struggles with complex refactors and architectural decisions -- great at straightforward tasks, mediocre on nuanced ones
−Cloud-based GitHub integration is unintuitive to set up -- many users find the workflow confusing
−No image input yet -- can't show it a screenshot of a UI bug and ask it to fix it
−Response latency can spike to 3+ minutes per response during peak hours

Pricing

Free

✓Basic Codex access
✓Quick coding tasks only
✓Explore capabilities

Go

$8/month

✓Lightweight coding tasks
✓Codex CLI access

Plus

$20/month

✓Codex web + CLI + IDE extension
✓GPT-5.4 + GPT-5.3-Codex
✓20-100 local messages per 5h
✓Slack integration
✓Cloud code review

Pro

$100/month

✓10-20x higher rate limits
✓GPT-5.3-Codex-Spark (research preview)
✓Up to 2,000 messages per 5h
✓Priority processing

Business

Pay as you go/per seat

✓30-150 local messages per 5h
✓10-60 cloud tasks per 5h
✓20-50 code reviews per 5h
✓Admin controls
✓Larger VMs

Known Issues

Security vulnerability discovered where branch parameter allowed shell command injection during environment setup -- fixed by OpenAI with improved input validationSource: BeyondTrust Phantom Labs, TechRadar · 2026-03
CLI was macOS-only at launch, frustrating Windows and Linux users -- broader platform support now rolling outSource: Reddit r/openai, GitHub issues · 2026-04
Code quality for complex tasks often needs significant human review before merging -- better at code review than code writing according to developer feedbackSource: Hacker News, Reddit r/programming · 2026-04

Best for

Developers already paying for ChatGPT Plus who want a coding agent at no extra cost. Especially good for parallel task execution -- assign multiple bug fixes or feature branches and let Codex work them simultaneously.

Not for

Developers who need fine-grained control mid-task (use Claude Code or Cursor instead). Also not ideal for complex architectural refactors where the AI needs human guidance throughout the process.

Our Verdict

Codex is OpenAI's answer to Claude Code and Devin, and it has one killer advantage: it's bundled with ChatGPT Plus. If you're already paying $20/mo for ChatGPT, you get a cloud coding agent for free. The parallel task execution is genuinely unique -- no other coding agent lets you fire off 5 tasks and check back later. But the rough edges are real: you can't steer it mid-task, complex refactors fall flat, and the usage limits feel tight. For straightforward coding tasks and code review, it's excellent. For anything nuanced, Claude Code's interactive approach is still better.