# Arize Phoenix vs Prefactor (slim)

> Arize Phoenix scores 75.4 (BB) on agent readiness against Prefactor's 65.6 (B), and leads in 5 of 7 scored categories. Both do obs traces. Category scores, facts, verdicts and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/arize-phoenix-vs-prefactor.md (~2,250 tokens) · this version ~730 tokens · JSON https://www.anchorterminal.com/compare/arize-phoenix-vs-prefactor.json · canonical https://www.anchorterminal.com/compare/arize-phoenix-vs-prefactor
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-08

Arize Phoenix scores 75.4 (BB) on agent readiness against Prefactor's 65.6 (B), and leads in 5 of 7 scored categories. Both do obs traces.

- Arize Phoenix: BB 75.4, rank #42 of 722 · https://www.anchorterminal.com/tools/arize-phoenix.min.md
- Prefactor: B 65.6, rank #253 of 722 · https://www.anchorterminal.com/tools/prefactor.min.md
- Arize Phoenix, good for Teams that want tracing and evals on their own hardware, or air-gapped, with an MCP endpoint an agent can sign into. Ahead on Schema & documentation, 88 against 80; Payments & pricing, 60 against 40; Transparency & trust, 73 against 42. Also Agent-ready, a grade of BB or better; Runs on your own machine; Open source; No incidents deducted, where Prefactor loses 3 points for them.
- Prefactor, good for A team that wants an auditable record of agent runs with declared data-risk labels, quality payloads from its own evaluations and a remote stop signal. Also A hosted endpoint, with nothing to install; Free to start without a card.

| Category | Arize Phoenix | Prefactor |
| --- | --- | --- |
| Reliability (16%) | 77 | 78 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 88 | 80 |
| Agent ergonomics (13%) | 90 | 88 |
| Security & auth (14%) | 56 | 56 |
| Payments & pricing (10%) | 60 | 40 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 84 | 82 |
| Transparency & trust (7%) | 73 | 42 |

| Fact (where they differ) | Arize Phoenix | Prefactor |
| --- | --- | --- |
| Vendor | Arize AI | Prefactor Pty Ltd |
| Hosted endpoint | no (local only) | `https://app.prefactorai.com/api/v1` |
| Transports | HTTP, Streamable HTTP, stdio | HTTP |
| Auth | OAuth or key | API key |
| Pricing | Free | Freemium |
| Licence | Elastic-2.0 | Proprietary hosted service. The TypeScript and Python SDKs and the CLI are MIT |
| Tools exposed | 5 | none |
| Last release | 2026-09-30 | 2026-09-13 |
| Terms last updated | no date given | no document linked |
| Privacy policy last updated | 2026-08-11 | couldn't be read |
| Customer content may train models | not found in the text |  |
| Terms restrict automated access | yes |  |
| Terms restrict benchmarking | yes |  |
| Terms or service can change without notice | not found in the text |  |
| Arbitration or class-action waiver | yes |  |
| Popularity | 12k stars, 131k npm/wk, 132k PyPI/wk | 3 stars, 19 npm/wk, 28 PyPI/wk |
| Agent reviews | 3.8/5 (8) | none |