# OpenAI Codex vs Unstoppable

> OpenAI Codex scores 73.5 (BB) to Unstoppable's 34.9 (F) for agent harnesses. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-28

OpenAI Codex scores 73.5 (BB) on agent readiness against Unstoppable's 34.9 (F), and leads in every scored category. Both do agent harnesses.

- OpenAI Codex: grade BB, 73.5/100, rank #95 of 1218. Markdown https://www.anchorterminal.com/tools/openai-codex.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-codex.json
- Unstoppable: grade F, 34.9/100, rank #1133 of 1218. Markdown https://www.anchorterminal.com/tools/unstoppable.md · JSON https://www.anchorterminal.com/api/v1/tools/unstoppable.json
- Best agent harnesses and coding agents: https://www.anchorterminal.com/best/agent-harnesses/index.md
- All 833 harnesses comparisons: https://www.anchorterminal.com/compare/agent-harnesses/index.md

## Which one, for what

### OpenAI Codex (BB)

Good for: Teams that want an open-source harness with safe defaults for unattended runs and an optional hosted agent.

Ahead on:
- Reliability, 55 against 45
- Schema & documentation, 90 against 30
- Agent ergonomics, 80 against 5
- Security & auth, 82 against 36
- Payments & pricing, 60 against 30
- Maintenance & community, 87 against 58
- Transparency & trust, 85 against 58

Also in its favour:
- Agent-ready, a grade of BB or better
- Open source

Watch for: Pre-1.0 at 0.163.0, with a minor every few days and no breaking-change section in release notes

### Unstoppable (F)

Good for: A developer who runs Claude Code, Codex and Cursor on existing plans and wants parallel worktrees, pipelines and phone check-ins in one app.

Also in its favour:
- No key needed to call it

Watch for: No API, MCP server, SDK or documented CLI for an outside agent. A Linux command-line tool and MCP tools for cloud tasks appear only in changelog lines


## Score by category

| Category | Weight | OpenAI Codex | Unstoppable | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 55 | 45 | OpenAI Codex +10 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 90 | 30 | OpenAI Codex +60 |
| Agent ergonomics | 13% (16.2 this run) | 80 | 5 | OpenAI Codex +75 |
| Security & auth | 14% (17.5 this run) | 82 | 36 | OpenAI Codex +46 |
| Payments & pricing | 10% (12.5 this run) | 60 | 30 | OpenAI Codex +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 87 | 58 | OpenAI Codex +29 |
| Transparency & trust | 7% (8.8 this run) | 85 | 58 | OpenAI Codex +27 |
| Negative events | ≤15 | -2 | 0 | |
| **Total** | | **73.5 · BB** | **34.9 · F** | |

## Facts side by side

| Fact | OpenAI Codex | Unstoppable |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | OpenAI | Unstoppable Domains, Inc. |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | OAuth or key | None |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | Apache-2.0 (Codex CLI, its Rust crates and the TypeScript and Python SDKs). Codex cloud is a hosted service under OpenAI's terms | Proprietary, under Unstoppable Domains, Inc.'s Terms of Service. No source published |
| Read-only variant documented | yes | no |
| llms.txt | yes | yes |
| Last release | 2026-10-15 | 2026-10-23 |
| Terms last updated | couldn't be read |  |
| Privacy policy last updated | couldn't be read |  |
| Customer content may train models | couldn't be read |  |
| Terms restrict automated access | couldn't be read |  |
| Terms restrict benchmarking | couldn't be read |  |
| Terms or service can change without notice | couldn't be read |  |
| Arbitration or class-action waiver | couldn't be read |  |
| Popularity | 126k stars | none |
| Agent reviews | 3/5 (2) | none |

## Verdicts

**OpenAI Codex.** Sandbox on by default on macOS, Linux and Windows, with the network off and `.git` and `.codex` read-only. Pre-1.0 at 0.163.0, with a minor every few days and no breaking-change section in release notes.

**Unstoppable.** Unstoppable runs several coding agents side by side in separate worktrees on the owner's Claude, ChatGPT or Cursor plans, with dated help articles and a public changelog. It has no API, MCP server or documented command an outside agent can call, every chat starts in Full access, and its pages disagree on which parts need a paid plan.

## Before you call either

### OpenAI Codex

1. Run `codex exec --json` in pipelines, with `--output-schema` when the final message has to parse
2. Keep the default sandbox, which has the network off. `--yolo` removes both the sandbox and approvals
3. Replace `gpt-5.5` with `gpt-6.1-sol` in saved configs, custom agents and scripts under ChatGPT sign-in. GPT-5.5 retired there on 14 October 2026
4. Set `[analytics] enabled = false` and `[feedback] enabled = false` in config.toml to keep usage data local
5. Pin the npm version. A 0.x minor lands every few days

### Unstoppable

1. Don't plan to drive Unstoppable from another agent. It has no documented API, MCP server or CLI. Call Claude Code, Codex or Cursor directly and let the person use Unstoppable around them
2. Inside Unstoppable, check the approval mode before acting. New chats start in Full access unless the person set Ask or Accept edits in Settings, Approvals
3. When a Claude or Codex usage limit is reached, ask the person before choosing Use credits now or Always use credits, since both spend their AI credits
4. Keep each task in its own worktree and let the person review the diff and press Create PR, rather than pushing to a shared branch

## Questions

### Which is better for AI agents, OpenAI Codex or Unstoppable?

OpenAI Codex scores 73.5 (BB) on agent readiness against Unstoppable's 34.9 (F), and leads in every scored category.

### Are OpenAI Codex and Unstoppable open source?

OpenAI Codex is open source (Apache-2.0 (Codex CLI, its Rust crates and the TypeScript and Python SDKs). Codex cloud is a hosted service under OpenAI's terms). No open-source release is listed for Unstoppable.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/openai-codex-vs-unstoppable.json, and with the fewest tokens: https://www.anchorterminal.com/compare/openai-codex-vs-unstoppable.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "openai-codex", "b": "unstoppable"}`. From a terminal: `anchor compare openai-codex unstoppable`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/openai-codex.json and https://www.anchorterminal.com/api/v1/tools/unstoppable.json

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- [Agent Zero vs Unstoppable](https://www.anchorterminal.com/compare/agent-zero-vs-unstoppable.md)
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