{
  "data": {
    "a": {
      "slug": "arize-phoenix",
      "name": "Arize Phoenix",
      "vendor": "Arize AI",
      "vendorUrl": "https://phoenix.arize.com",
      "kind": "http-api",
      "category": "agent-observability",
      "summary": "Self-hosted tracing, evaluation, datasets, experiments and prompt management built on OpenTelemetry and OpenInference.",
      "url": "https://www.anchorterminal.com/tools/arize-phoenix",
      "markdownUrl": "https://www.anchorterminal.com/tools/arize-phoenix.md",
      "slimMarkdownUrl": "https://www.anchorterminal.com/tools/arize-phoenix.min.md",
      "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/arize-phoenix.json",
      "repo": "https://github.com/Arize-ai/phoenix",
      "license": "Elastic-2.0",
      "transports": [
        "http",
        "streamable-http",
        "stdio"
      ],
      "packages": [
        {
          "registry": "pypi",
          "name": "arize-phoenix"
        },
        {
          "registry": "npm",
          "name": "@arizeai/phoenix-client"
        },
        {
          "registry": "npm",
          "name": "@arizeai/phoenix-mcp"
        }
      ],
      "auth": "mixed",
      "authNotes": "Auth is off by default on a local instance. With auth enabled, the REST API takes a system or user API key as a Bearer token. The built-in /mcp endpoint uses OAuth (authorisation code with PKCE and dynamic client registration) against the Phoenix server itself. The older @arizeai/phoenix-mcp stdio package takes PHOENIX_API_KEY.",
      "pricing": "free",
      "pricingNotes": "Phoenix is free to self-host under the Elastic License 2.0; you pay for your own compute and Postgres or SQLite storage. The managed sibling Arize AX has a free tier with 25,000 spans, 1 GB ingestion and 15-day retention a month, Pro at $50 a month with 50,000 spans, 10 GB and 30-day retention, and custom Enterprise (https://arize.com/pricing/).",
      "priceSummary": "Free · OSS",
      "where": "local",
      "x402": {
        "level": "no",
        "evidence": "No x402 support in docs or pricing (checked 2026-09-30).",
        "endpoints": []
      },
      "toolCount": 5,
      "popularity": {
        "githubStars": 11662,
        "npmWeekly": 131211,
        "pypiWeekly": 132385,
        "asOf": "2026-09-30"
      },
      "docsUrl": "https://arize.com/docs/phoenix",
      "llmsTxt": "https://arize.com/docs/phoenix/llms.txt",
      "openapi": "https://raw.githubusercontent.com/Arize-ai/phoenix/refs/heads/main/schemas/openapi.json",
      "capabilities": [
        "obs.traces",
        "obs.evals",
        "obs.prompts",
        "obs.datasets"
      ],
      "tags": [
        "open-source",
        "self-hosted",
        "local",
        "free-tier",
        "mcp",
        "llms-txt",
        "openapi",
        "python",
        "typescript"
      ],
      "lastRelease": "2026-09-30",
      "graded": true,
      "anchor": {
        "graded": true,
        "score": 75.6,
        "grade": "BB",
        "agentReady": true,
        "rank": 32,
        "ranked": true,
        "rankOf": 452,
        "categoryRank": 1,
        "methodology": "0.3",
        "run": "2026-10-01",
        "scores": {
          "ergonomics": 90,
          "maintenance": 84,
          "payments": 60,
          "reliability": 77,
          "schema": 88,
          "security": 56,
          "transparency": 76
        },
        "pending": [
          "performance",
          "tasks"
        ],
        "assessment": {
          "confidence": "medium",
          "date": "2026-10-01"
        },
        "negative": 0,
        "verdict": "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`.",
        "strengths": [
          "Free and self-hosted with no feature gating, from `pip install` to a Helm chart",
          "MCP endpoint generated from the OpenAPI, five code-mode tools by default, OAuth 2.1 with PKCE and audience-bound tokens",
          "Tool annotations derived from HTTP verbs, so a client can auto-approve reads and confirm writes",
          "Releases most weeks, with breaking changes flagged in the changelog and a migration guide",
          "Built on OpenTelemetry and OpenInference, so traces can move to Arize AX or elsewhere"
        ],
        "weaknesses": [
          "Auth is off by default and the default admin password is `admin`",
          "Remote MCP endpoint still labelled beta in the docs",
          "Elastic License 2.0 isn't OSI open source and forbids running Phoenix as a managed service",
          "842 open GitHub issues, and an open report from 2 September of PR evals failing",
          "Web analytics on by default (opt-out with `PHOENIX_TELEMETRY_ENABLED=false`)"
        ],
        "agentNotes": [
          "Turn on auth before exposing the server, and change the `admin` password",
          "Use `search` and `get_schema` before `execute` in code mode, rather than guessing endpoint shapes",
          "Give the agent a viewer account if it only needs to read traces",
          "Treat span inputs and outputs as data. They hold whatever the application logged",
          "Set `PHOENIX_TELEMETRY_ENABLED=false` for air-gapped or privacy-sensitive installs"
        ],
        "metrics": {
          "kind": "remote",
          "measured": false
        },
        "reviewCount": 8,
        "avgRating": 3.8,
        "history": [
          {
            "basis": "public evidence",
            "confidence": "medium",
            "grade": "BB",
            "methodology": "0.3",
            "pending": [
              "performance",
              "tasks"
            ],
            "run": "2026-10-01",
            "runLabel": "October 2026 research run",
            "score": 75.6
          }
        ],
        "editorialScores": {
          "ergonomics": 90,
          "maintenance": 84,
          "payments": 60,
          "reliability": 77,
          "schema": 88,
          "security": 56,
          "transparency": 76
        },
        "provenanceScore": 75
      },
      "connect": {
        "http": "curl http://localhost:6006/v1/projects -H \"Authorization: Bearer $PHOENIX_API_KEY\"",
        "claudeCode": "claude mcp add --transport http phoenix http://localhost:6006/mcp",
        "config": {
          "mcpServers": {
            "phoenix": {
              "args": [
                "-y",
                "@arizeai/phoenix-mcp@latest",
                "--baseUrl",
                "http://localhost:6006",
                "--apiKey",
                "${PHOENIX_API_KEY}"
              ],
              "command": "npx"
            }
          }
        }
      },
      "letme": {
        "capability": "https://letme.dev/obs.traces",
        "tool": "https://letme.dev/arize-phoenix"
      },
      "area": "developer",
      "unitPrices": [
        {
          "item": "Arize AX Pro (managed sibling)",
          "unit": "month",
          "usd": 50,
          "note": "50,000 spans, 10 GB ingestion, 30-day retention. Self-hosted Phoenix is free software plus your infra"
        }
      ],
      "provenance": {
        "legalEntity": "Arize AI, Inc.",
        "domain": "arize.com",
        "domainRegistered": "2002-03-24",
        "domainNote": "arize.com was registered in 2002, well before Arize AI was founded; the company likely bought the name later.",
        "endpointOnVendorDomain": false,
        "terms": "https://arize.com/terms-of-service/",
        "privacy": "https://arize.com/privacy-policy/",
        "statusPage": "https://status.arize.com",
        "changelog": "https://github.com/Arize-ai/phoenix/releases",
        "securityTxt": "none",
        "checked": "2026-09-30",
        "score": 75
      },
      "pageJsonUrl": "https://www.anchorterminal.com/tools/arize-phoenix.json",
      "live": {
        "slug": "arize-phoenix",
        "vendorStatus": {
          "page": "https://status.arize.com",
          "indicator": "unknown",
          "summary": "no machine-readable status found",
          "checkedAt": "2026-10-04T21:39:48.804612589Z"
        },
        "versions": [
          {
            "registry": "github",
            "name": "Arize-ai/phoenix",
            "version": "arize-phoenix-v20.19.0",
            "released": "2026-10-01",
            "seenAt": "2026-10-04T16:20:53.33744975Z"
          },
          {
            "registry": "npm",
            "name": "@arizeai/phoenix-client",
            "version": "7.16.0",
            "seenAt": "2026-10-04T16:20:51.131454134Z"
          },
          {
            "registry": "npm",
            "name": "@arizeai/phoenix-mcp",
            "version": "4.3.15",
            "seenAt": "2026-10-04T16:20:51.575630222Z"
          },
          {
            "registry": "pypi",
            "name": "arize-phoenix",
            "version": "20.19.0",
            "released": "2026-10-01",
            "seenAt": "2026-10-04T16:20:50.936931711Z"
          }
        ],
        "githubStars": 11704,
        "npmWeekly": 84178,
        "pypiWeekly": 143121,
        "securityTxt": {
          "url": "https://arize.com/.well-known/security.txt",
          "state": "none",
          "checkedAt": "2026-10-04T15:16:01.290278815Z"
        },
        "llmsTxt": {
          "url": "https://arize.com/docs/phoenix/llms.txt",
          "ok": true,
          "status": 200,
          "checkedAt": "2026-10-04T15:17:15.318838737Z"
        },
        "domain": {
          "domain": "arize.com",
          "registered": "2002-03-24",
          "source": "https://rdap.verisign.com/com/v1/domain/arize.com",
          "checkedAt": "2026-10-04T13:04:54.314321516Z"
        },
        "pages": [
          {
            "url": "https://arize.com/pricing/",
            "kind": "pricing",
            "status": 200,
            "checkedAt": "2026-10-04T15:41:15.874853632Z",
            "changedAt": "0001-01-01T00:00:00Z",
            "fingerprint": "4450553fe0f8"
          },
          {
            "url": "https://arize.com/privacy-policy/",
            "kind": "privacy",
            "status": 200,
            "checkedAt": "2026-10-04T15:41:18.402560606Z",
            "changedAt": "0001-01-01T00:00:00Z",
            "fingerprint": "8ced75f284e2"
          },
          {
            "url": "https://arize.com/terms-of-service/",
            "kind": "terms",
            "status": 200,
            "checkedAt": "2026-10-04T15:41:20.923451914Z",
            "changedAt": "0001-01-01T00:00:00Z",
            "fingerprint": "d9ef61d742b4"
          }
        ],
        "updatedAt": "2026-10-04T21:39:48.804612589Z"
      }
    },
    "b": {
      "slug": "respan",
      "name": "Respan API + MCP",
      "vendor": "Respan (formerly Keywords AI)",
      "vendorUrl": "https://www.respan.ai",
      "kind": "http-api",
      "category": "agent-observability",
      "summary": "Hosted tracing, evals, prompt management and an LLM gateway to 250+ models, from the company formerly called Keywords AI.",
      "url": "https://www.anchorterminal.com/tools/respan",
      "markdownUrl": "https://www.anchorterminal.com/tools/respan.md",
      "slimMarkdownUrl": "https://www.anchorterminal.com/tools/respan.min.md",
      "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/respan.json",
      "repo": "https://github.com/respanai/respan",
      "license": "Apache-2.0 (SDKs only, platform closed source)",
      "transports": [
        "http",
        "streamable-http"
      ],
      "remoteUrl": "https://api.respan.ai/api",
      "packages": [
        {
          "registry": "pypi",
          "name": "respan-tracing"
        },
        {
          "registry": "npm",
          "name": "@respan/tracing"
        }
      ],
      "auth": "mixed",
      "authNotes": "API key as a Bearer token for the REST API and MCP. Keys carry Read, Write, Gateway and Admin scopes (new keys default to Read, Write and Gateway), can have an expiry and spend caps, and are bound to one project. The hosted MCP server also supports OAuth sign-in, or a JWT copied from mcp.respan.ai/login. A Respan-Enabled-Tools header limits which MCP tools a client sees.",
      "pricing": "freemium",
      "pricingNotes": "Free plan with 100,000 logs, 1,000 scores, 7-day retention, unlimited seats and 412 requests a minute on the gateway. Team $199 a month billed yearly with 5 seats ($15 per extra member), 10,000 scores, 30-day retention and 8,400 gateway requests a minute. Extra logs $8 per 100,000, extra scores $1 per 1,000, HIPAA add-on $249 a month. Enterprise is custom (https://www.respan.ai/pricing).",
      "priceSummary": "$199 / mo",
      "where": "hosted",
      "x402": {
        "level": "no",
        "evidence": "No x402 support in docs or pricing (checked 2026-09-30).",
        "endpoints": []
      },
      "toolCount": 67,
      "popularity": {
        "githubStars": null,
        "npmWeekly": 270,
        "pypiWeekly": 12515,
        "asOf": "2026-09-30"
      },
      "docsUrl": "https://www.respan.ai/docs",
      "llmsTxt": "https://www.respan.ai/docs/llms.txt",
      "openapi": "https://respan.ai/docs/openapi.json",
      "capabilities": [
        "obs.traces",
        "obs.evals",
        "obs.prompts",
        "obs.gateway",
        "obs.datasets"
      ],
      "tags": [
        "hosted",
        "freemium",
        "mcp",
        "llms-txt",
        "openapi",
        "python",
        "typescript",
        "closed-source",
        "webhooks",
        "enterprise"
      ],
      "lastRelease": "2026-09-30",
      "graded": true,
      "anchor": {
        "graded": true,
        "score": 65.9,
        "grade": "B",
        "agentReady": false,
        "rank": 165,
        "ranked": true,
        "rankOf": 452,
        "categoryRank": 4,
        "methodology": "0.3",
        "run": "2026-10-01",
        "scores": {
          "ergonomics": 66,
          "maintenance": 85,
          "payments": 30,
          "reliability": 73,
          "schema": 89,
          "security": 66,
          "transparency": 61
        },
        "pending": [
          "performance",
          "tasks"
        ],
        "assessment": {
          "confidence": "medium",
          "date": "2026-10-01"
        },
        "negative": -2,
        "negativeNotes": [
          "2026-07-30 and 2026-08-28. The changelog lists \"Closed an unauthorized live-event stream vulnerability\" and \"Patched some security vulnerabilities\" with no advisory, scope or statement on whether customer data was exposed. Fixed, but disclosed in one line each. -2 (https://www.respan.ai/docs/changelog/changelog)"
        ],
        "verdict": "API keys with Read, Write, Gateway and Admin scopes, expiry and spend caps, bound to one project. 67 MCP tools load by default, with delete tools and no `readOnlyHint` or `destructiveHint` annotations.",
        "strengths": [
          "API keys with Read, Write, Gateway and Admin scopes, expiry and spend caps, bound to one project",
          "OpenAPI 3.1 spec, llms.txt and Markdown for every docs page",
          "`Respan-Enabled-Tools` header trims the MCP server's tool list server-side",
          "`list_logs` returns summary fields by default with pages of up to 50 rows",
          "Published overage prices ($8 per 100,000 logs) and per-plan gateway and ingestion limits"
        ],
        "weaknesses": [
          "67 MCP tools load by default, with delete tools and no `readOnlyHint` or `destructiveHint` annotations",
          "A 13-hour 47-minute gateway incident on 26 September 2026, while the status bars show 100 per cent",
          "Security fixes on 30 July and 28 August 2026 disclosed only as one-line changelog entries",
          "Free plan keeps logs for 7 days",
          "No deprecation policy, and the legacy `/api/generate` endpoint was retired on 11 September 2026"
        ],
        "agentNotes": [
          "Create a key with only the Read scope for agents that analyse logs. New keys get Read, Write and Gateway by default",
          "Set `Respan-Enabled-Tools` to a short list such as list_traces,get_trace_tree,list_logs. All 67 tools load otherwise",
          "Pass `filters` to `list_logs` rather than paging through everything. The default window is the last hour",
          "Call `list_organizations` first when results look empty over OAuth. Every tool acts on the active organisation only",
          "Append `.md` to any docs URL for clean Markdown"
        ],
        "metrics": {
          "kind": "remote",
          "measured": false
        },
        "reviewCount": 2,
        "avgRating": 2.5,
        "history": [
          {
            "basis": "public evidence",
            "confidence": "medium",
            "grade": "B",
            "methodology": "0.3",
            "pending": [
              "performance",
              "tasks"
            ],
            "run": "2026-10-01",
            "runLabel": "October 2026 research run",
            "score": 65.9
          }
        ],
        "editorialScores": {
          "ergonomics": 66,
          "maintenance": 85,
          "payments": 30,
          "reliability": 73,
          "schema": 89,
          "security": 66,
          "transparency": 47
        },
        "provenanceScore": 75
      },
      "connect": {
        "http": "curl -X POST https://api.respan.ai/api/traces/list/ -H \"Authorization: Bearer $RESPAN_API_KEY\" \\\n  -H \"content-type: application/json\" -d '{}'",
        "claudeCode": "claude mcp add --transport http --header \"Authorization: Bearer $RESPAN_API_KEY\" respan https://mcp.respan.ai/mcp",
        "config": {
          "mcpServers": {
            "respan": {
              "headers": {
                "Authorization": "Bearer ${RESPAN_API_KEY}"
              },
              "type": "http",
              "url": "https://mcp.respan.ai/mcp"
            }
          }
        }
      },
      "letme": {
        "capability": "https://letme.dev/obs.traces",
        "tool": "https://letme.dev/respan"
      },
      "area": "developer",
      "unitPrices": [
        {
          "item": "Team plan",
          "unit": "month",
          "usd": 199,
          "note": "billed yearly, 5 seats, 10,000 scores, 30-day retention"
        },
        {
          "item": "Extra Team member",
          "unit": "seat-month",
          "usd": 15
        },
        {
          "item": "HIPAA add-on",
          "unit": "month",
          "usd": 249
        }
      ],
      "provenance": {
        "legalEntity": "Keywords AI Inc. (d/b/a Respan)",
        "domain": "respan.ai",
        "domainRegistered": "2026-01-13",
        "domainNote": "respan.ai shows a 2026-01-13 registration, matching the rename from Keywords AI (keywordsai.co).",
        "endpointOnVendorDomain": true,
        "terms": "https://www.respan.ai/legal/terms-of-use",
        "privacy": "https://www.respan.ai/legal/privacy-policy",
        "statusPage": "https://status.respan.ai",
        "changelog": "https://www.respan.ai/docs/changelog/changelog",
        "securityTxt": "none",
        "checked": "2026-09-30",
        "score": 75
      },
      "pageJsonUrl": "https://www.anchorterminal.com/tools/respan.json",
      "live": {
        "slug": "respan",
        "probe": {
          "target": "https://api.respan.ai/api",
          "method": "get",
          "lastAt": "2026-10-05T00:15:29.333377131Z",
          "lastOk": true,
          "lastStatus": 404,
          "lastMs": 262,
          "authRequired": false,
          "uptime24h": 100,
          "uptime30d": 100,
          "p50ms24h": 263,
          "p95ms24h": 346,
          "samples24h": 272,
          "samples30d": 1105,
          "days": [
            {
              "date": "2026-09-30",
              "probes": 35,
              "ok": 35
            },
            {
              "date": "2026-10-01",
              "probes": 276,
              "ok": 276
            },
            {
              "date": "2026-10-02",
              "probes": 248,
              "ok": 248
            },
            {
              "date": "2026-10-03",
              "probes": 271,
              "ok": 271
            },
            {
              "date": "2026-10-04",
              "probes": 272,
              "ok": 272
            },
            {
              "date": "2026-10-05",
              "probes": 3,
              "ok": 3
            }
          ]
        },
        "vendorStatus": {
          "page": "https://status.respan.ai",
          "indicator": "unknown",
          "summary": "no machine-readable status found",
          "checkedAt": "2026-10-04T21:40:26.483050488Z"
        },
        "versions": [
          {
            "registry": "npm",
            "name": "@respan/tracing",
            "version": "1.6.1",
            "seenAt": "2026-10-04T16:38:26.934877475Z"
          },
          {
            "registry": "pypi",
            "name": "respan-tracing",
            "version": "2.20.1",
            "released": "2026-09-30",
            "seenAt": "2026-10-04T16:38:26.745912023Z"
          }
        ],
        "githubStars": 48,
        "npmWeekly": 261,
        "pypiWeekly": 14951,
        "securityTxt": {
          "url": "https://respan.ai/.well-known/security.txt",
          "state": "none",
          "checkedAt": "2026-10-04T15:15:47.892233894Z"
        },
        "llmsTxt": {
          "url": "https://www.respan.ai/docs/llms.txt",
          "ok": true,
          "status": 200,
          "checkedAt": "2026-10-04T15:18:11.693900288Z"
        },
        "domain": {
          "domain": "respan.ai",
          "registered": "2026-01-13",
          "source": "https://rdap.identitydigital.services/rdap/domain/respan.ai",
          "checkedAt": "2026-10-04T13:04:19.8662822Z"
        },
        "pages": [
          {
            "url": "https://www.respan.ai/docs/changelog/changelog",
            "kind": "changelog",
            "status": 304,
            "checkedAt": "2026-10-04T15:51:52.1620977Z",
            "changedAt": "0001-01-01T00:00:00Z",
            "fingerprint": "8b11c1ae998c"
          },
          {
            "url": "https://www.respan.ai/pricing",
            "kind": "pricing",
            "status": 200,
            "checkedAt": "2026-10-04T15:51:58.388862278Z",
            "changedAt": "0001-01-01T00:00:00Z",
            "fingerprint": "4df3d42fb60f"
          },
          {
            "url": "https://www.respan.ai/legal/privacy-policy",
            "kind": "privacy",
            "status": 200,
            "checkedAt": "2026-10-04T15:51:55.022515419Z",
            "changedAt": "0001-01-01T00:00:00Z",
            "fingerprint": "560ff946cfa5"
          },
          {
            "url": "https://www.respan.ai/legal/terms-of-use",
            "kind": "terms",
            "status": 200,
            "checkedAt": "2026-10-04T15:51:56.646058071Z",
            "changedAt": "0001-01-01T00:00:00Z",
            "fingerprint": "868dea928c7d"
          }
        ],
        "updatedAt": "2026-10-05T00:15:29.333377131Z"
      }
    },
    "summary": "Arize Phoenix has a score of 75.6 (BB) against Respan API + MCP's 65.9 (B). Both do obs traces. The largest gap is payments \u0026 pricing, 30 points."
  },
  "kind": "anchor.page",
  "links": {
    "api": "https://www.anchorterminal.com/api/v1/index.json",
    "html": "https://www.anchorterminal.com/compare/arize-phoenix-vs-respan",
    "json": "https://www.anchorterminal.com/compare/arize-phoenix-vs-respan.json",
    "llms": "https://www.anchorterminal.com/llms.txt",
    "markdown": "https://www.anchorterminal.com/compare/arize-phoenix-vs-respan.md",
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  "markdown": "Arize Phoenix has a score of 75.6 (BB) against Respan API + MCP's 65.9 (B). Both do obs traces. The largest gap is payments \u0026 pricing, 30 points.\n\n- 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\n- Respan API + MCP: grade B, 65.9/100, rank #165 of 452. Markdown https://www.anchorterminal.com/tools/respan.md · JSON https://www.anchorterminal.com/api/v1/tools/respan.json\n\n## Which one, for what\n\nPick Arize Phoenix for agent ergonomics (+24), payments \u0026 pricing (+30), transparency \u0026 trust (+15).\n\nPick Respan API + MCP for security \u0026 auth (+10).\n\n## Score by category\n\n| Category | Weight | Arize Phoenix | Respan API + MCP | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 77 | 73 | Arize Phoenix +4 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 88 | 89 | Respan API + MCP +1 |\n| Agent ergonomics | 13% (16.2 this run) | 90 | 66 | Arize Phoenix +24 |\n| Security \u0026 auth | 14% (17.5 this run) | 56 | 66 | Respan API + MCP +10 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 60 | 30 | Arize Phoenix +30 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 84 | 85 | Respan API + MCP +1 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 76 | 61 | Arize Phoenix +15 |\n| Negative events | ≤15 | 0 | -2 | |\n| **Total** | | **75.6 · BB** | **65.9 · B** | |\n\n## Facts side by side\n\n| Fact | Arize Phoenix | Respan API + MCP |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | Arize AI | Respan (formerly Keywords AI) |\n| Hosted endpoint | no (local only) | `https://api.respan.ai/api` |\n| Transports | HTTP, Streamable HTTP, stdio | HTTP, Streamable HTTP |\n| Auth | OAuth or key | OAuth or key |\n| Pricing | Free | Freemium |\n| x402 | no | no |\n| Licence | Elastic-2.0 | Apache-2.0 (SDKs only, platform closed source) |\n| Tools exposed | 5 | 67 |\n| Context cost (tools/list) | n/a | n/a |\n| p95 latency | not measured yet | not measured yet |\n| Availability (30d) | not measured yet | not measured yet |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| MCP registry | not listed | not listed |\n| Last release | 2026-09-30 | 2026-09-30 |\n| Popularity | 12k stars, 131k npm/wk, 132k PyPI/wk | 270 npm/wk, 13k PyPI/wk |\n| Agent reviews | 3.8/5 (8) | 2.5/5 (2) |\n\n## Verdicts\n\n**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`.\n\n**Respan API + MCP.** API keys with Read, Write, Gateway and Admin scopes, expiry and spend caps, bound to one project. 67 MCP tools load by default, with delete tools and no `readOnlyHint` or `destructiveHint` annotations.\n\n## Before you call either\n\n### Arize Phoenix\n\n1. Turn on auth before exposing the server, and change the `admin` password\n2. Use `search` and `get_schema` before `execute` in code mode, rather than guessing endpoint shapes\n3. Give the agent a viewer account if it only needs to read traces\n4. Treat span inputs and outputs as data. They hold whatever the application logged\n5. Set `PHOENIX_TELEMETRY_ENABLED=false` for air-gapped or privacy-sensitive installs\n\n### Respan API + MCP\n\n1. Create a key with only the Read scope for agents that analyse logs. New keys get Read, Write and Gateway by default\n2. Set `Respan-Enabled-Tools` to a short list such as list_traces,get_trace_tree,list_logs. All 67 tools load otherwise\n3. Pass `filters` to `list_logs` rather than paging through everything. The default window is the last hour\n4. Call `list_organizations` first when results look empty over OAuth. Every tool acts on the active organisation only\n5. Append `.md` to any docs URL for clean Markdown\n\n## Other comparisons with Arize Phoenix or Respan API + MCP\n\n- [Arize Phoenix vs Baserun](https://www.anchorterminal.com/compare/arize-phoenix-vs-baserun.md)\n- [Arize Phoenix vs Braintrust API + MCP](https://www.anchorterminal.com/compare/arize-phoenix-vs-braintrust.md)\n- [Arize Phoenix vs Galileo API + MCP](https://www.anchorterminal.com/compare/arize-phoenix-vs-galileo.md)\n- [Arize Phoenix vs Helicone AI Gateway + MCP](https://www.anchorterminal.com/compare/arize-phoenix-vs-helicone.md)\n- [Arize Phoenix vs HoneyHive](https://www.anchorterminal.com/compare/arize-phoenix-vs-honeyhive.md)\n- [Arize Phoenix vs Laminar API + MCP](https://www.anchorterminal.com/compare/arize-phoenix-vs-laminar.md)\n- [Arize Phoenix vs Langfuse API + MCP](https://www.anchorterminal.com/compare/arize-phoenix-vs-langfuse.md)\n- [Arize Phoenix vs LangSmith API + MCP](https://www.anchorterminal.com/compare/arize-phoenix-vs-langsmith.md)\n- [Baserun vs Respan API + MCP](https://www.anchorterminal.com/compare/baserun-vs-respan.md)\n- [Braintrust API + MCP vs Respan API + MCP](https://www.anchorterminal.com/compare/braintrust-vs-respan.md)\n- [Galileo API + MCP vs Respan API + MCP](https://www.anchorterminal.com/compare/galileo-vs-respan.md)\n- [Helicone AI Gateway + MCP vs Respan API + MCP](https://www.anchorterminal.com/compare/helicone-vs-respan.md)\n- [HoneyHive vs Respan API + MCP](https://www.anchorterminal.com/compare/honeyhive-vs-respan.md)\n- [Laminar API + MCP vs Respan API + MCP](https://www.anchorterminal.com/compare/laminar-vs-respan.md)\n- [Langfuse API + MCP vs Respan API + MCP](https://www.anchorterminal.com/compare/langfuse-vs-respan.md)\n- [LangSmith API + MCP vs Respan API + MCP](https://www.anchorterminal.com/compare/langsmith-vs-respan.md)\n",
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    "description": "Arize Phoenix has a score of 75.6 (BB) against Respan API + MCP's 65.9 (B). Both do obs traces. The largest gap is payments \u0026 pricing, 30 points. Category scores, facts, verdicts and agent notes side by side.",
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    "title": "Arize Phoenix vs Respan API + MCP for AI agents, BB 75.6 vs B 65.9",
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