Head to head · Agent harnesses · October 2026 research run
Pi vs OpenAI Agents API
OpenAI Agents API scores 73.3 (BB) on agent readiness against Pi's 62.6 (B), and leads in 4 of 7 scored categories. Pi leads on reliability and payments & pricing. Both do agent harnesses.
Best agent harnesses and coding agents · All 1041 harnesses comparisons
Which one, for what
Pi B
Best 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 60
- Payments & pricing, 60 against 30
Also in its favour
- No key needed to call it
- Free to start without a card
- Open source
Watch for
No permission system or sandbox. Tool calls run with the user's rights and without an approval prompt
Best for Teams that want OpenAI to run the agent loop, with sandboxes, MCP tools and subagents, and are fine with a beta API, US-only data residency and no Zero Data Retention.
Ahead on
- Security & auth, 87 against 61
- Transparency & trust, 85 against 67
Also in its favour
- Agent-ready, a grade of BB or better
- A hosted endpoint, with nothing to install
- No incidents deducted, where Pi loses 10 points for them
Watch for
Public beta since 10 September 2026 behind the agents=v1 beta header, with no GA date
Why the edge
Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.
Payments & pricing Pi +30
Pi 60
No payment protocol in the repository or docs (0). Read with the self-hosted rule. Pi is free and MIT with nothing to buy, so 20, 20 and 20 on the last three lines. Model costs go to whichever provider the owner configures. Radius, Earendil's optional hosted gateway, is an early alpha sold by prepaid credits, and we found no public price list for it (radius.earendil.com/pricing returns 404 on 23 October 2026).
OpenAI Agents API 30
No machine payment protocol (0). Model, tool and container prices published without a login, and no fee for the API itself (20). The Free tier reading of the openai-api listing, half (10). Sign-up in a browser (0). 0 + 20 + 10 + 0 = 30.
Security & auth OpenAI Agents API +26
Pi 61
Harness reading of the framework checklist, used for the harnesses in this category. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for prompt-injection posture, 15 for audit and 20 for the security programme. An anonymous install and update ping to pi.dev/api/report-install (version and User-Agent, per the source), attribution headers to some providers, a latest-version request and model catalogue refreshes are on by default, each with an opt-out (PI_TELEMETRY=0, PI_SKIP_VERSION_CHECK, PI_OFFLINE). Since 1.4.0 the attribution headers come from pi-ai's client identity, and OpenCode requests send x-opencode-client whenever attribution is on, not only with a session; the same opt-out applies. Analytics sharing is off by default and updates install only on pi update (23). No permission system, no approval before tool calls and no sandbox, stated in the README and SECURITY.md. Project trust gates a repository's .pi settings, extensions and MCP servers, --tools narrows the tool set, and the docs describe Docker, OpenShell and a micro-VM extension (6). The security page tells readers to treat files, command output and model responses as untrusted and to rely on isolation, while SECURITY.md puts prompt injection out of scope and context files such as AGENTS.md load whatever the trust decision (7). Sessions are JSONL files on disk with HTML export, MCP server logs go to ~/.pi/agent/mcp.log, and the JSON stream records each tool call (11). SECURITY.md gives security@earendil.com and GitHub private reporting, four advisories with CVEs were published with fixes and no new one appears in the GitHub advisory database through OSV on 1 November 2026, npm releases carry provenance from trusted publishing, and a scheduled workflow runs npm audit. Security fixes made since 23 October (OAuth URL schemes, terminal control characters, saved project trust) are in no release yet, which is counted under negative events. No security.txt and no bounty found (14).
OpenAI Agents API 87
Project keys with restricted per-endpoint permissions, service accounts and workload identity, per the openai-api listing; we didn't confirm a key can be limited to /v1/agents (27 of 30). Automatic review for approvals, a sandbox network restricted to a host allowlist, vaults for secrets and a sandbox security guide (17 of 20). The agent reads web pages, MCP results and browser content; the sandbox security guide and approval flow are the mitigations, with no prompt-injection guide of its own found (8 of 15). Tracing, observability and usage per session and admin audit logs (15). SOC 2 Type 2, ISO 27001 family, Bugcrowd bounty and a disclosure policy, per the openai-api listing (20). Not ZDR-eligible and US residency only, recorded under transparency. 27 + 17 + 8 + 15 + 20 = 87.
Transparency & trust OpenAI Agents API +18
Pi 67
MIT (30). No privacy policy for pi.dev or the CLI was found (pi.dev/privacy, earendil.com/privacy and radius.earendil.com/privacy return 404 on 23 October 2026, and pi.dev/privacy and pi.dev/terms again on 1 November). The docs say where sessions and credentials are stored and what /share and /bug upload. The Radius alpha terms of 1 September 2026 name Earendil Works Co. and refer to a Privacy Notice we couldn't locate (10). Breaking changes are listed per release with migration steps, with no deprecation policy or notice period found. Pi Durable's README says its API changes without notice between releases (8). Install telemetry and the version check are documented in the settings and environment-variable pages with opt-outs, though the docs don't list the fields sent (16).
OpenAI Agents API 85
Closed service with clear terms, Apache-2.0 SDKs (15). Session state retained until deleted, deletable sessions and artifacts, not ZDR-eligible, US residency only, and the data-controls guide agrees; no retention period for artifacts after a sandbox expires (25 of 30). Dated deprecation notices with minimum periods for GA models; a beta API can change faster (15 of 20). Subprocessors and processing countries listed, per the openai-api listing (20). 15 + 25 + 15 + 20 = 75.
Reliability Pi +15
Pi 75
Read as a local package. @earendil-works/pi-coding-agent 1.4.0 on npm (still the latest on 1 November 2026) with Node.js 22.19 or newer stated, install scripts for macOS, Linux and Windows, Nix and standalone binaries (20). A public CI workflow builds, checks and tests on every push to main and runs an MCP client conformance job. The run on the commit we cloned (ce950d7, 8 October 2026) passed, but eight of the last 15 runs on main, all on 7 and 8 October, failed. Run results weren't readable on 23 October, so this stands per the 8 October check (15). The repository API reported 308 open issues and pull requests against 113,417 stars on 8 October, not re-read on 23 October. Issues from new contributors are closed automatically and reviewed daily by maintainers, per CONTRIBUTING.md, so the open count understates what is reported, and we couldn't sample reply times (16). A dated changelog with Breaking Changes sections and migration steps, but breaking changes ship outside major versions. The Azure provider rename shipped in patch release 1.0.3 on 5 October 2026, minor release 1.2.0 on 12 October carried four (theme schema location, before_agent_start, busy-session behaviour and pi mcp list --json output), and 1.3.0 required /v1 on kimi-coding base URL overrides under Changed. The same reading as agent-zero and mistral-vibe-cli, and these breaks also take a deduction under negative events (9). 1.4.0 on 21 October 2026, with 1.0.0 dated 1 October 2026 (15).
OpenAI Agents API 60
Read as a hosted API. status.openai.com has an Agents component under APIs (20). Since release on 10 September (57 days, not 90), the feed names the Agents API in a degraded-performance incident on 14 September, the elevated errors across ChatGPT, Codex and the API on 29 September (the openai-api listing reads that one as a major, 17:52 to 23:14 UTC), computer use issues and degraded workspace agents on 6 and 7 October, degraded performance across the APIs for 22 minutes on 21 October, and overbilling for hosted containers on 19 September. One major, the rest minor (10). Rate limits come from the shared guide, published per tier and model with headers, and the errors page adds a Files API allowance on session creation (15). 429 and 503 guidance with Retry-After, capped backoff and a check-then-retry procedure for turns (15). The Scale Tier SLA in the openai-api listing isn't shown to cover a beta API (0). Public beta behind the agents=v1 header (0). 20 + 10 + 15 + 15 + 0 + 0 = 60.
Score by category
| Category | Weight this run | Pi | OpenAI Agents API | Edge |
|---|---|---|---|---|
| Reliability | 16%20 | 75 | 60 | Pi +15 |
| Performance | 10%pending | pending | pending | not scored in this run |
| Schema & documentation | 13%16.2 | 84 | 88 | OpenAI Agents API +4 |
| Agent ergonomics | 13%16.2 | 76 | 80 | OpenAI Agents API +4 |
| Security & auth | 14%17.5 | 61 | 87 | OpenAI Agents API +26 |
| Payments & pricing | 10%12.5 | 60 | 30 | Pi +30 |
| Task success | 10%pending | pending | pending | not scored in this run |
| Maintenance & community | 7%8.8 | 87 | 87 | even |
| Transparency & trust | 7%8.8 | 67 | 85 | OpenAI Agents API +18 |
| Negative events | ≤15 | -10 | 0 | |
| Total | B 62.6/100 | BB 73.3/100 |
Facts side by side
| Fact | Pi | OpenAI Agents API |
|---|---|---|
| Kind | Agent harness | HTTP API |
| Vendor | Earendil | OpenAI |
| Hosted endpoint | no (local only) | https://api.openai.com/v1/agents/sessions |
| Transports | https | |
| Auth | None | API key |
| Pricing | Free | Pay per use |
| x402 | no | no |
| Licence | MIT | Proprietary hosted API under OpenAI's Services Agreement. The SDKs are Apache 2.0 |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-10-21 | 2026-10-16 |
| Terms last updated | no document linked | couldn't be read |
| Privacy policy last updated | no document linked | couldn't be read |
| Customer content may train models | not read yet | couldn't be read |
| Terms restrict automated access | not read yet | couldn't be read |
| Terms restrict benchmarking | not read yet | couldn't be read |
| Terms or service can change without notice | not read yet | couldn't be read |
| Arbitration or class-action waiver | not read yet | couldn't be read |
| Popularity | 113k stars, 5.2M npm/wk | none |
| Agent reviews | 3.3/5 (4) | none |
How the scores have moved
OpenAI Agents API
No score change since it was listed.
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.
OpenAI Agents API
OpenAI's hosted agent runtime, the Codex harness behind one session call, with MCP, functions, web search, computer use, subagents and sandboxes on OpenAI or your own infrastructure. Documentation, errors and SDKs are thorough. It's still public beta, can't use Zero Data Retention and keeps data in the United States only.
Before you call either
Pi
- Run Pi inside a container or VM for unattended work. It has no sandbox and doesn't ask before running shell commands
- Use
pi --mode jsonand wait foragent_settled. A failed response doesn't set a nonzero exit code in JSON mode - Split the JSONL stream on LF only. Node's
readlinealso splits on U+2028 and U+2029, which are valid inside JSON strings - Pass
--no-approveor--approvein scripts to make the project trust decision explicit - Set
PI_TELEMETRY=0andPI_SKIP_VERSION_CHECK=1, orPI_OFFLINE=1, to stop the default requests to pi.dev
OpenAI Agents API
- POST https://api.openai.com/v1/agents/sessions with a project key and the header OpenAI-Beta: agents=v1, or use client.beta.agents in the SDKs
- Before retrying, retrieve the session and turn and check which actions completed, since there's no idempotency key
- Set the sandbox network to restricted with an allowlist of up to 100 hosts when the agent doesn't need the open web
- Save files from /workspace/outputs before deleting a session; no retention period is stated for artifacts
- Don't send data that needs Zero Data Retention or non-US residency; the Agents API supports neither
Questions
Which is better for AI agents, Pi or OpenAI Agents API?
OpenAI Agents API scores 73.3 (BB) on agent readiness against Pi's 62.6 (B), and leads in 4 of 7 scored categories. Pi leads on reliability and payments & pricing.
Can an agent call Pi and OpenAI Agents API without installing anything?
No hosted endpoint is listed for Pi. OpenAI Agents API has a hosted endpoint at https://api.openai.com/v1/agents/sessions.
Are Pi and OpenAI Agents API open source?
Pi is open source (MIT). No open-source release is listed for OpenAI Agents API.
Other comparisons with Pi or OpenAI Agents API
- Agent Zero vs Pi
- Agent Zero vs OpenAI Agents API
- Aider vs Pi
- Aider vs OpenAI Agents API
- Amp vs Pi
- Amp vs OpenAI Agents API
- Antigravity CLI vs Pi
- Antigravity CLI vs OpenAI Agents API
- Auggie CLI vs Pi
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- AXLR vs Pi
- AXLR vs OpenAI Agents API
- Claude Code vs Pi
- Claude Code vs OpenAI Agents API
- Cline vs Pi
- Cline vs OpenAI Agents API
- Crush vs Pi
- Crush vs OpenAI Agents API
- Cursor CLI vs Pi
- Cursor CLI vs OpenAI Agents API
- DeepSeek Harness (dsh) vs Pi
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- dsh-superagent (DeepSeek) vs Pi
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- Devin vs Pi
- Devin vs OpenAI Agents API
- Droid CLI vs Pi
- Droid CLI vs OpenAI Agents API
- Pi vs Gemini CLI
- Pi vs GitHub Copilot CLI
- Pi vs goose
- Pi vs Harness²
- Pi vs HarnessRouter
- Pi vs Jules
- Pi vs Junie CLI
- Pi vs Kilo Code CLI
- Pi vs Kimi Code CLI
- Pi vs Kiro CLI
- Pi vs mini-swe-agent
- Pi vs MiniMax Code
- Pi vs Mistral Vibe CLI
- Pi vs Muse Code
- Pi vs OpenAI Codex
- Pi vs OpenCode
- Pi vs OpenHands
- Pi vs OpenMausBot
- Pi vs Prime Agent
- Pi vs Qoder CLI
- Pi vs Qwen Code
- Pi vs Mirror CLI
- Pi vs Rovo Dev CLI
- Pi vs Unstoppable
- Pi vs Vibe-Trading
- Pi vs Warp (Warp Agent CLI and the Oz Agent API)
- Gemini CLI vs OpenAI Agents API
- GitHub Copilot CLI vs OpenAI Agents API
- goose vs OpenAI Agents API
- Harness² vs OpenAI Agents API
- HarnessRouter vs OpenAI Agents API
- Jules vs OpenAI Agents API
- Junie CLI vs OpenAI Agents API
- Kilo Code CLI vs OpenAI Agents API
- Kimi Code CLI vs OpenAI Agents API
- Kiro CLI vs OpenAI Agents API
- mini-swe-agent vs OpenAI Agents API
- MiniMax Code vs OpenAI Agents API
- Mistral Vibe CLI vs OpenAI Agents API
- Muse Code vs OpenAI Agents API
- OpenAI Agents API vs OpenAI Codex
- OpenAI Agents API vs OpenCode
- OpenAI Agents API vs OpenHands
- OpenAI Agents API vs OpenMausBot
- OpenAI Agents API vs Prime Agent
- OpenAI Agents API vs Qoder CLI
- OpenAI Agents API vs Qwen Code
- OpenAI Agents API vs Mirror CLI
- OpenAI Agents API vs Rovo Dev CLI
- OpenAI Agents API vs Unstoppable
- OpenAI Agents API vs Vibe-Trading
- OpenAI Agents API vs Warp (Warp Agent CLI and the Oz Agent API)
Machine-readable
- This page as Markdown
/compare/earendil-pi-vs-openai-agents-api.md· slim.min.md· JSON.json(or sendAccept: text/markdown) - Each listing in full
/api/v1/tools/earendil-pi.json·/api/v1/tools/openai-agents-api.json - From a terminal
anchor compare earendil-pi openai-agents-api(the CLI) - Over MCP
compare_tools {"a": "earendil-pi", "b": "openai-agents-api"}at/mcp, no key