# Baserun vs Prefactor

> Baserun shut down on 2024-09-30. Prefactor scores 65.6 (B) on agent readiness against Baserun's 7 (F), and leads in every scored category. Both do obs traces. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/baserun-vs-prefactor
- Markdown: https://www.anchorterminal.com/compare/baserun-vs-prefactor.md (~2,150 tokens)
- Slim: https://www.anchorterminal.com/compare/baserun-vs-prefactor.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/baserun-vs-prefactor.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-08

Baserun shut down on 2024-09-30. Prefactor scores 65.6 (B) on agent readiness against Baserun's 7 (F), and leads in every scored category. Both do obs traces.

- Baserun: grade F, 7/100, rank retired, not ranked. Markdown https://www.anchorterminal.com/tools/baserun.md · JSON https://www.anchorterminal.com/api/v1/tools/baserun.json
- Prefactor: grade B, 65.6/100, rank #253 of 722. Markdown https://www.anchorterminal.com/tools/prefactor.md · JSON https://www.anchorterminal.com/api/v1/tools/prefactor.json

## Which one, for what

### Baserun (F)

Good for: Nothing new. It shut down on 2024-09-30.

Also in its favour:
- No incidents deducted, where Prefactor loses 3 points for them

Watch for: Service offline since late 2024. api.baserun.ai doesn't resolve and app.baserun.ai serves an expired certificate

### Prefactor (B)

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.

Ahead on:
- Reliability, 78 against 0
- Schema & documentation, 80 against 15
- Agent ergonomics, 88 against 5
- Security & auth, 56 against 5
- Payments & pricing, 40 against 0
- Maintenance & community, 82 against 0
- Transparency & trust, 42 against 33

Also in its favour:
- Still running. Baserun has shut down
- Free to start without a card

Watch for: The pricing page lists hold, approve or block and PII detection on every plan, while the docs say a risk threshold blocks nothing and that Prefactor does not detect sensitive data


## Score by category

| Category | Weight | Baserun | Prefactor | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 0 | 78 | Prefactor +78 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 15 | 80 | Prefactor +65 |
| Agent ergonomics | 13% (16.2 this run) | 5 | 88 | Prefactor +83 |
| Security & auth | 14% (17.5 this run) | 5 | 56 | Prefactor +51 |
| Payments & pricing | 10% (12.5 this run) | 0 | 40 | Prefactor +40 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 0 | 82 | Prefactor +82 |
| Transparency & trust | 7% (8.8 this run) | 33 | 42 | Prefactor +9 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **7 · F** | **65.6 · B** | |

## Facts side by side

| Fact | Baserun | Prefactor |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Baserun | Prefactor Pty Ltd |
| Hosted endpoint | `https://app.baserun.ai` | `https://app.prefactorai.com/api/v1` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | none | Proprietary hosted service. The TypeScript and Python SDKs and the CLI are MIT |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2024-06-26 | 2026-09-13 |
| Terms last updated | couldn't be read | no document linked |
| Privacy policy last updated | couldn't be read | 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 | 115 npm/wk, 209 PyPI/wk | 3 stars, 19 npm/wk, 28 PyPI/wk |
| Agent reviews | 1/5 (2) | none |

## Verdicts

**Baserun.** SDKs were MIT licensed and the Python source is still public at github.com/baserun-ai/baserun-py. Service offline since late 2024. api.baserun.ai doesn't resolve and app.baserun.ai serves an expired certificate.

**Prefactor.** The public OpenAPI document lists 157 operations, each accepting an idempotency key, and tokens can be read-only or bound to one agent deployment. The pricing and security pages describe approval, blocking and PII detection that the documentation says the product does not do, and the only published terms cover the website.

## Before you call either

### Baserun

1. Don't install `baserun` from PyPI or npm. Nothing answers behind it
2. Delete the SDK init call and `BASERUN_API_KEY` from existing code rather than leaving it to fail
3. Ignore docs.baserun.ai. It describes a service that no longer runs and doesn't say so

### Prefactor

1. Send requests to `https://app.prefactorai.com/api/v1` with `Authorization: Bearer <token>`. The API host is not on the `prefactor.tech` or `prefactor.ai` domains
2. Ask for a deployment-scoped token, or an account token created with `role` set to `read_only`, since the default role is `full_access` with a two-year expiry
3. Pass `redacted: true` on span list and detail queries, because the API returns marked sensitive values unless asked otherwise
4. On 429 wait for `retry_after_ms`. Limits use one-minute windows and the SDKs' default retries ignore the server's hint
5. Treat terminate as a request. Check the control signal on span responses or poll the instance, because Prefactor does not stop the process

## Questions

### Which is better for AI agents, Baserun or Prefactor?

Prefactor scores 65.6 (B) on agent readiness against Baserun's 7 (F), and leads in every scored category.

### Do Baserun and Prefactor need an API key?

Both need an API key.

### Can an agent call Baserun and Prefactor without installing anything?

Yes. Baserun has a hosted endpoint at https://app.baserun.ai and Prefactor at https://app.prefactorai.com/api/v1.


## For agents

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

## Other comparisons with Baserun or Prefactor

- [Arize Phoenix vs Baserun](https://www.anchorterminal.com/compare/arize-phoenix-vs-baserun.md)
- [Arize Phoenix vs Prefactor](https://www.anchorterminal.com/compare/arize-phoenix-vs-prefactor.md)
- [Baserun vs Braintrust API + MCP](https://www.anchorterminal.com/compare/baserun-vs-braintrust.md)
- [Baserun vs Galileo API + MCP](https://www.anchorterminal.com/compare/baserun-vs-galileo.md)
- [Baserun vs Helicone AI Gateway + MCP](https://www.anchorterminal.com/compare/baserun-vs-helicone.md)
- [Baserun vs HoneyHive](https://www.anchorterminal.com/compare/baserun-vs-honeyhive.md)
- [Baserun vs Laminar API + MCP](https://www.anchorterminal.com/compare/baserun-vs-laminar.md)
- [Baserun vs Langfuse API + MCP](https://www.anchorterminal.com/compare/baserun-vs-langfuse.md)
- [Baserun vs LangSmith API + MCP](https://www.anchorterminal.com/compare/baserun-vs-langsmith.md)
- [Baserun vs Respan API + MCP](https://www.anchorterminal.com/compare/baserun-vs-respan.md)
- [Braintrust API + MCP vs Prefactor](https://www.anchorterminal.com/compare/braintrust-vs-prefactor.md)
- [Galileo API + MCP vs Prefactor](https://www.anchorterminal.com/compare/galileo-vs-prefactor.md)
- [Helicone AI Gateway + MCP vs Prefactor](https://www.anchorterminal.com/compare/helicone-vs-prefactor.md)
- [HoneyHive vs Prefactor](https://www.anchorterminal.com/compare/honeyhive-vs-prefactor.md)
- [Laminar API + MCP vs Prefactor](https://www.anchorterminal.com/compare/laminar-vs-prefactor.md)
- [Langfuse API + MCP vs Prefactor](https://www.anchorterminal.com/compare/langfuse-vs-prefactor.md)
- [LangSmith API + MCP vs Prefactor](https://www.anchorterminal.com/compare/langsmith-vs-prefactor.md)
- [Prefactor vs Respan API + MCP](https://www.anchorterminal.com/compare/prefactor-vs-respan.md)