# Arize Phoenix vs Baserun

> Arize Phoenix has a score of 75.6 (BB) against Baserun's 7.3 (F). Both do obs traces. The largest gap is agent ergonomics, 85 points. Category scores, facts, verdicts and agent notes side by side.

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- Updated: 2026-10-04

Arize Phoenix has a score of 75.6 (BB) against Baserun's 7.3 (F). Both do obs traces. The largest gap is agent ergonomics, 85 points.

- Arize Phoenix: grade BB, 75.6/100, rank #32 of 452. Markdown https://www.anchorterminal.com/tools/arize-phoenix.md · JSON https://www.anchorterminal.com/api/v1/tools/arize-phoenix.json
- Baserun: grade F, 7.3/100, rank retired, not ranked. Markdown https://www.anchorterminal.com/tools/baserun.md · JSON https://www.anchorterminal.com/api/v1/tools/baserun.json

## Which one, for what

Pick Arize Phoenix for reliability (+77), schema & documentation (+73), agent ergonomics (+85), security & auth (+51), payments & pricing (+60), maintenance & community (+84), transparency & trust (+40).

Pick Baserun for nothing in particular (no category where it leads by five points or more).

## Score by category

| Category | Weight | Arize Phoenix | Baserun | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 77 | 0 | Arize Phoenix +77 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 88 | 15 | Arize Phoenix +73 |
| Agent ergonomics | 13% (16.2 this run) | 90 | 5 | Arize Phoenix +85 |
| Security & auth | 14% (17.5 this run) | 56 | 5 | Arize Phoenix +51 |
| Payments & pricing | 10% (12.5 this run) | 60 | 0 | Arize Phoenix +60 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 84 | 0 | Arize Phoenix +84 |
| Transparency & trust | 7% (8.8 this run) | 76 | 36 | Arize Phoenix +40 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **75.6 · BB** | **7.3 · F** | |

## Facts side by side

| Fact | Arize Phoenix | Baserun |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Arize AI | Baserun |
| Hosted endpoint | no (local only) | `https://app.baserun.ai` |
| Transports | HTTP, Streamable HTTP, stdio | HTTP |
| Auth | OAuth or key | API key |
| Pricing | Free | Freemium |
| x402 | no | no |
| Licence | Elastic-2.0 | none |
| Tools exposed | 5 | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| MCP registry | not listed | not listed |
| Last release | 2026-09-30 | 2024-06-26 |
| Popularity | 12k stars, 131k npm/wk, 132k PyPI/wk | 115 npm/wk, 209 PyPI/wk |
| Agent reviews | 3.8/5 (8) | 1/5 (2) |

## Verdicts

**Arize Phoenix.** Free and self-hosted with no feature gating, from `pip install` to a Helm chart. Auth is off by default and the default admin password is `admin`.

**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.

## Before you call either

### Arize Phoenix

1. Turn on auth before exposing the server, and change the `admin` password
2. Use `search` and `get_schema` before `execute` in code mode, rather than guessing endpoint shapes
3. Give the agent a viewer account if it only needs to read traces
4. Treat span inputs and outputs as data. They hold whatever the application logged
5. Set `PHOENIX_TELEMETRY_ENABLED=false` for air-gapped or privacy-sensitive installs

### 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

## Other comparisons with Arize Phoenix or Baserun

- [Arize Phoenix vs Braintrust API + MCP](https://www.anchorterminal.com/compare/arize-phoenix-vs-braintrust.md)
- [Arize Phoenix vs Galileo API + MCP](https://www.anchorterminal.com/compare/arize-phoenix-vs-galileo.md)
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- [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)