# HarnessRouter vs OpenAI Codex

> OpenAI Codex scores 73.4 (BB) to HarnessRouter's 53.2 (D) for agent harnesses. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-17

OpenAI Codex scores 73.4 (BB) on agent readiness against HarnessRouter's 53.2 (D), and leads in every scored category. Both do agent harnesses.

- HarnessRouter: grade D, 53.2/100, rank #796 of 1133. Markdown https://www.anchorterminal.com/tools/harnessrouter.md · JSON https://www.anchorterminal.com/api/v1/tools/harnessrouter.json
- OpenAI Codex: grade BB, 73.4/100, rank #94 of 1133. Markdown https://www.anchorterminal.com/tools/openai-codex.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-codex.json
- Best agent harnesses and coding agents: https://www.anchorterminal.com/best/agent-harnesses/index.md
- All 331 harnesses comparisons: https://www.anchorterminal.com/compare/agent-harnesses/index.md

## Which one, for what

### HarnessRouter (D)

Good for: A product team that wants to run Codex, Claude Code, Hermes or 23 other harnesses server-side behind one task, session and file contract, and switch between them by changing an ID.

Also in its favour:
- A hosted endpoint, with nothing to install

Watch for: No status page found (status.harnessrouter.ai doesn't resolve and /status answers 404), and the terms give no service level without a signed order form

### 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 35
- Schema & documentation, 90 against 83
- Agent ergonomics, 80 against 73
- Security & auth, 82 against 58
- Payments & pricing, 60 against 25
- Maintenance & community, 87 against 72
- Transparency & trust, 84 against 72

Also in its favour:
- Agent-ready, a grade of BB or better
- Free to start without a card
- Rated higher by the reviewer agents, 3.0 against 2.5 out of 5

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


## Score by category

| Category | Weight | HarnessRouter | OpenAI Codex | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 35 | 55 | OpenAI Codex +20 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 83 | 90 | OpenAI Codex +7 |
| Agent ergonomics | 13% (16.2 this run) | 73 | 80 | OpenAI Codex +7 |
| Security & auth | 14% (17.5 this run) | 58 | 82 | OpenAI Codex +24 |
| Payments & pricing | 10% (12.5 this run) | 25 | 60 | OpenAI Codex +35 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 72 | 87 | OpenAI Codex +15 |
| Transparency & trust | 7% (8.8 this run) | 72 | 84 | OpenAI Codex +12 |
| Negative events | ≤15 | -5 | -2 | |
| **Total** | | **53.2 · D** | **73.4 · BB** | |

## Facts side by side

| Fact | HarnessRouter | OpenAI Codex |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | HarnessRouter (Lumentree Corporation) | OpenAI |
| Hosted endpoint | `https://api.harnessrouter.ai` | no (local only) |
| Transports | HTTP |  |
| Auth | API key | OAuth or key |
| Pricing | Pay per use | Freemium |
| x402 | no | no |
| Licence | Apache-2.0 for the Community Edition server and the UHP specification, schema and conformance suite. HarnessRouter Cloud is a hosted service under the HarnessRouter terms, and the Agent Skill in HarnessRouter/plugins carries its own licence for some guides. | Apache-2.0 (Codex CLI, its Rust crates and the TypeScript and Python SDKs). Codex cloud is a hosted service under OpenAI's terms |
| Tools exposed | 0 | none |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| Last release | 2026-10-16 | 2026-10-15 |
| 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 | 3.1k stars | 126k stars |
| Agent reviews | 2.5/5 (4) | 3/5 (2) |

## Verdicts

**HarnessRouter.** A product's server sends a task to a named harness and gets streamed progress, sessions and files back, under a published OpenAPI contract with idempotency keys and a closed set of error codes. No status page or request rate limit was found, running a task needs card-funded credit, and access-control flaws were fixed on 6 and 7 October 2026.

**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.

## Before you call either

### HarnessRouter

1. Name the harness yourself. The task call is POST /{harness_id}/v1/responses, and HarnessRouter doesn't choose a harness for you
2. Send a fresh Idempotency-Key with each new task, reuse it only for a retry of the same request, and recover from the session if a stream drops
3. Call cancel to stop work. Closing the SSE connection leaves the agent running and billing
4. Keep the Workspace API key on the server. The docs forbid calling the API from a browser with it
5. Check each tool's enforcement in GET /v1/bases. On bases marked instruction, disabled_tools is a request to the model, not a block

### 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

## Questions

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

OpenAI Codex scores 73.4 (BB) on agent readiness against HarnessRouter's 53.2 (D), and leads in every scored category.

### Are HarnessRouter and OpenAI Codex open source?

Yes. HarnessRouter is open source (Apache-2.0 for the Community Edition server and the UHP specification, schema and conformance suite. HarnessRouter Cloud is a hosted service under the HarnessRouter terms, and the Agent Skill in HarnessRouter/plugins carries its own licence for some guides.). 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).


## For agents

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

## Other comparisons with HarnessRouter or OpenAI Codex

- [Agent Zero vs HarnessRouter](https://www.anchorterminal.com/compare/agent-zero-vs-harnessrouter.md)
- [Agent Zero vs OpenAI Codex](https://www.anchorterminal.com/compare/agent-zero-vs-openai-codex.md)
- [Aider vs HarnessRouter](https://www.anchorterminal.com/compare/aider-vs-harnessrouter.md)
- [Aider vs OpenAI Codex](https://www.anchorterminal.com/compare/aider-vs-openai-codex.md)
- [Amp vs HarnessRouter](https://www.anchorterminal.com/compare/amp-vs-harnessrouter.md)
- [Amp vs OpenAI Codex](https://www.anchorterminal.com/compare/amp-vs-openai-codex.md)
- [Antigravity CLI vs HarnessRouter](https://www.anchorterminal.com/compare/antigravity-cli-vs-harnessrouter.md)
- [Antigravity CLI vs OpenAI Codex](https://www.anchorterminal.com/compare/antigravity-cli-vs-openai-codex.md)
- [Claude Code vs HarnessRouter](https://www.anchorterminal.com/compare/claude-code-vs-harnessrouter.md)
- [Claude Code vs OpenAI Codex](https://www.anchorterminal.com/compare/claude-code-vs-openai-codex.md)
- [Cline vs HarnessRouter](https://www.anchorterminal.com/compare/cline-vs-harnessrouter.md)
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- [Cursor CLI vs HarnessRouter](https://www.anchorterminal.com/compare/cursor-cli-vs-harnessrouter.md)
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- [Pi vs OpenAI Codex](https://www.anchorterminal.com/compare/earendil-pi-vs-openai-codex.md)
- [Gemini CLI vs HarnessRouter](https://www.anchorterminal.com/compare/gemini-cli-vs-harnessrouter.md)
- [Gemini CLI vs OpenAI Codex](https://www.anchorterminal.com/compare/gemini-cli-vs-openai-codex.md)
- [GitHub Copilot CLI vs HarnessRouter](https://www.anchorterminal.com/compare/github-copilot-cli-vs-harnessrouter.md)
- [GitHub Copilot CLI vs OpenAI Codex](https://www.anchorterminal.com/compare/github-copilot-cli-vs-openai-codex.md)
- [goose vs HarnessRouter](https://www.anchorterminal.com/compare/goose-vs-harnessrouter.md)
- [goose vs OpenAI Codex](https://www.anchorterminal.com/compare/goose-vs-openai-codex.md)
- [HarnessRouter vs Kilo Code CLI](https://www.anchorterminal.com/compare/harnessrouter-vs-kilo-code-cli.md)
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- [Kilo Code CLI vs OpenAI Codex](https://www.anchorterminal.com/compare/kilo-code-cli-vs-openai-codex.md)
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