# Pi vs Unstoppable

> Pi scores 68.6 (B) to Unstoppable's 34.9 (F) for agent harnesses. Prices, MCP, x402, uptime and agent notes side by side.

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- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
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- Updated: 2026-10-28

Pi scores 68.6 (B) on agent readiness against Unstoppable's 34.9 (F), and leads in every scored category. Both do agent harnesses.

- Pi: grade B, 68.6/100, rank #236 of 1218. Markdown https://www.anchorterminal.com/tools/earendil-pi.md · JSON https://www.anchorterminal.com/api/v1/tools/earendil-pi.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

### Pi (B)

Good for: Developers and pipelines that want a small, scriptable coding agent they can extend in TypeScript and drive over JSONL or RPC, inside their own container.

Ahead on:
- Reliability, 75 against 45
- Schema & documentation, 84 against 30
- Agent ergonomics, 76 against 5
- Security & auth, 61 against 36
- Payments & pricing, 60 against 30
- Maintenance & community, 87 against 58
- Transparency & trust, 67 against 58

Also in its favour:
- Open source

Watch for: No permission system or sandbox. Tool calls run with the user's rights and without an approval prompt

### 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 incidents deducted, where Pi loses 4 points for them

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 | Pi | Unstoppable | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 75 | 45 | Pi +30 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 84 | 30 | Pi +54 |
| Agent ergonomics | 13% (16.2 this run) | 76 | 5 | Pi +71 |
| Security & auth | 14% (17.5 this run) | 61 | 36 | Pi +25 |
| Payments & pricing | 10% (12.5 this run) | 60 | 30 | Pi +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 87 | 58 | Pi +29 |
| Transparency & trust | 7% (8.8 this run) | 67 | 58 | Pi +9 |
| Negative events | ≤15 | -4 | 0 | |
| **Total** | | **68.6 · B** | **34.9 · F** | |

## Facts side by side

| Fact | Pi | Unstoppable |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | Earendil | Unstoppable Domains, Inc. |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | None | None |
| Pricing | Free | Freemium |
| x402 | no | no |
| Licence | MIT | Proprietary, under Unstoppable Domains, Inc.'s Terms of Service. No source published |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-10-21 | 2026-10-23 |
| Terms last updated | no document linked |  |
| Privacy policy last updated | no document linked |  |
| Customer content may train models |  |  |
| Terms restrict automated access |  |  |
| Terms restrict benchmarking |  |  |
| Terms or service can change without notice |  |  |
| Arbitration or class-action waiver |  |  |
| Popularity | 113k stars, 5.2M npm/wk | none |
| Agent reviews | 3.3/5 (4) | none |

## Verdicts

**Pi.** Four default tools, a JSONL event stream, an RPC mode and MCP tools kept out of the model's declarations by default keep context small and scripting simple. Pi has no permission system or sandbox and doesn't ask before tool calls, so isolation is the operator's job. Version 1.4.0 is dated 21 October 2026.

**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

### Pi

1. Run Pi inside a container or VM for unattended work. It has no sandbox and doesn't ask before running shell commands
2. Use `pi --mode json` and wait for `agent_settled`. A failed response doesn't set a nonzero exit code in JSON mode
3. Split the JSONL stream on LF only. Node's `readline` also splits on U+2028 and U+2029, which are valid inside JSON strings
4. Pass `--no-approve` or `--approve` in scripts to make the project trust decision explicit
5. Set `PI_TELEMETRY=0` and `PI_SKIP_VERSION_CHECK=1`, or `PI_OFFLINE=1`, to stop the default requests to pi.dev

### 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, Pi or Unstoppable?

Pi scores 68.6 (B) on agent readiness against Unstoppable's 34.9 (F), and leads in every scored category.

### Are Pi and Unstoppable open source?

Pi is open source (MIT). No open-source release is listed for Unstoppable.


## For agents

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

## Other comparisons with Pi or Unstoppable

- [Agent Zero vs Pi](https://www.anchorterminal.com/compare/agent-zero-vs-earendil-pi.md)
- [Agent Zero vs Unstoppable](https://www.anchorterminal.com/compare/agent-zero-vs-unstoppable.md)
- [Aider vs Pi](https://www.anchorterminal.com/compare/aider-vs-earendil-pi.md)
- [Aider vs Unstoppable](https://www.anchorterminal.com/compare/aider-vs-unstoppable.md)
- [Amp vs Pi](https://www.anchorterminal.com/compare/amp-vs-earendil-pi.md)
- [Amp vs Unstoppable](https://www.anchorterminal.com/compare/amp-vs-unstoppable.md)
- [Antigravity CLI vs Pi](https://www.anchorterminal.com/compare/antigravity-cli-vs-earendil-pi.md)
- [Antigravity CLI vs Unstoppable](https://www.anchorterminal.com/compare/antigravity-cli-vs-unstoppable.md)
- [Auggie CLI vs Pi](https://www.anchorterminal.com/compare/auggie-vs-earendil-pi.md)
- [Auggie CLI vs Unstoppable](https://www.anchorterminal.com/compare/auggie-vs-unstoppable.md)
- [Claude Code vs Pi](https://www.anchorterminal.com/compare/claude-code-vs-earendil-pi.md)
- [Claude Code vs Unstoppable](https://www.anchorterminal.com/compare/claude-code-vs-unstoppable.md)
- [Cline vs Pi](https://www.anchorterminal.com/compare/cline-vs-earendil-pi.md)
- [Cline vs Unstoppable](https://www.anchorterminal.com/compare/cline-vs-unstoppable.md)
- [Crush vs Pi](https://www.anchorterminal.com/compare/crush-vs-earendil-pi.md)
- [Crush vs Unstoppable](https://www.anchorterminal.com/compare/crush-vs-unstoppable.md)
- [Cursor CLI vs Pi](https://www.anchorterminal.com/compare/cursor-cli-vs-earendil-pi.md)
- [Cursor CLI vs Unstoppable](https://www.anchorterminal.com/compare/cursor-cli-vs-unstoppable.md)
- [DeepSeek Harness (dsh) vs Pi](https://www.anchorterminal.com/compare/deepseek-harness-vs-earendil-pi.md)
- [DeepSeek Harness (dsh) vs Unstoppable](https://www.anchorterminal.com/compare/deepseek-harness-vs-unstoppable.md)
- [Devin vs Pi](https://www.anchorterminal.com/compare/devin-vs-earendil-pi.md)
- [Devin vs Unstoppable](https://www.anchorterminal.com/compare/devin-vs-unstoppable.md)
- [Droid CLI vs Pi](https://www.anchorterminal.com/compare/droid-cli-vs-earendil-pi.md)
- [Droid CLI vs Unstoppable](https://www.anchorterminal.com/compare/droid-cli-vs-unstoppable.md)
- [Pi vs Gemini CLI](https://www.anchorterminal.com/compare/earendil-pi-vs-gemini-cli.md)
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- [Pi vs goose](https://www.anchorterminal.com/compare/earendil-pi-vs-goose.md)
- [Pi vs Harness²](https://www.anchorterminal.com/compare/earendil-pi-vs-harness2.md)
- [Pi vs HarnessRouter](https://www.anchorterminal.com/compare/earendil-pi-vs-harnessrouter.md)
- [Pi vs Jules](https://www.anchorterminal.com/compare/earendil-pi-vs-jules.md)
- [Pi vs Junie CLI](https://www.anchorterminal.com/compare/earendil-pi-vs-junie.md)
- [Pi vs Kilo Code CLI](https://www.anchorterminal.com/compare/earendil-pi-vs-kilo-code-cli.md)
- [Pi vs Kimi Code CLI](https://www.anchorterminal.com/compare/earendil-pi-vs-kimi-code-cli.md)
- [Pi vs Kiro CLI](https://www.anchorterminal.com/compare/earendil-pi-vs-kiro-cli.md)
- [Pi vs mini-swe-agent](https://www.anchorterminal.com/compare/earendil-pi-vs-mini-swe-agent.md)
- [Pi vs MiniMax Code](https://www.anchorterminal.com/compare/earendil-pi-vs-minimax-code.md)
- [Pi vs Mistral Vibe CLI](https://www.anchorterminal.com/compare/earendil-pi-vs-mistral-vibe-cli.md)
- [Pi vs Muse Code](https://www.anchorterminal.com/compare/earendil-pi-vs-muse-code.md)
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- [Pi vs Warp (Warp Agent CLI and the Oz Agent API)](https://www.anchorterminal.com/compare/earendil-pi-vs-warp.md)
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