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OpenAI Codex

OpenAI's coding agent across CLI, IDE, desktop app and cloud tasks.

Official site: openai.com Free tier: Yes Open source: Yes Platforms: CLI, IDE, Desktop, Web
Last verified: Oct 15, 2026 Last tested: Not yet, hands-on test pending
⚠ Preliminary, based on public research, hands-on test pending. These scores come from a desk review of public sources (official pricing pages, docs, changelogs), linked on each tool page. Rex hasn't run the hands-on tests yet, so tiers shown are projected. Under our rubric, a tool's official tier is capped at B until it's tested.

What looks good

  • Included in every ChatGPT plan, even Free
  • GPT-6 Astra arrived in Codex in Sep 2026
  • Codex CLI is open source; usage visible with /status

Watch-outs

  • Plus gets only an estimated 5-45 GPT-6 Astra messages per 5-hour window
  • Weekly limits may apply on top of the 5-hour window

From public sources below, not from our own hands-on testing (yet).

Scores

Rank #2 · projected tier A · official tier B (untested cap) · ⚠ Preliminary

Buffed in Sep 2026 with GPT-6 Astra, and included in every ChatGPT plan. Plus-tier Astra limits are tight.

Output quality on the job test 31/35
Speed & friction 13/15
Value / price 10/15
Control & ownership 7/10
Momentum & community 10/10
Reliability & trust 8/10
Builder-fit 5/5
Total84/100

Pricing as found Oct 15, 2026

PlanPriceNotes
Free / Go$0 / Go priceTry Codex with limited usage
Plus$20/moExpanded Codex usage, limited GPT-6 Astra
Profrom $100/moMaximum Codex tasks, GPT-6 Astra within allowance
Business$20/seat/mo2+ seats, billed annually
API keyUsage-basedStandard API rates

Prices in USD, excluding tax. Vendors change pricing often; check the official page before buying.

Patch history

buff

Codex CLI 0.163.0: steer mid-task instantly

Sending a follow-up while Codex is responding now steers the active turn right away, and interrupting also stops running Code Mode cells and their nested tool calls. The release also adds a searchable /config and parallel read-only tool calls. Source

buff

GPT-6 Astra lands in Codex

OpenAI rolled GPT-6 Astra into Codex starting Sep 3, 2026. Included within the allowance on Pro and the $100 Business plan; Plus gets limited Astra usage with optional credits. Source

Alternatives

S
Claude Code
86/100 · projected
A
Cursor
80/100 · projected
A
GitHub Copilot
79/100 · projected
A
Cline
78/100 · projected

Sources

  1. Codex pricing (chatgpt.com)
  2. ChatGPT pricing (openai.com)
  3. OpenAI: GPT-6 Astra (openai.com)

Accessed Oct 15, 2026. Spot an error? Request a correction.