{ "data": { "a": { "slug": "langfuse", "name": "Langfuse API + MCP", "vendor": "Langfuse (ClickHouse)", "vendorUrl": "https://langfuse.com", "kind": "http-api", "category": "agent-observability", "summary": "Open-source tracing, evaluation, prompt management and datasets for LLM apps and agents, built on OpenTelemetry.", "url": "https://www.anchorterminal.com/tools/langfuse", "markdownUrl": "https://www.anchorterminal.com/tools/langfuse.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/langfuse.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/langfuse.json", "repo": "https://github.com/langfuse/langfuse", "license": "MIT (core), commercial licence for the ee directories", "transports": [ "http", "streamable-http" ], "remoteUrl": "https://cloud.langfuse.com/api/public", "packages": [ { "registry": "pypi", "name": "langfuse" }, { "registry": "npm", "name": "@langfuse/tracing" }, { "registry": "npm", "name": "@langfuse/client" } ], "auth": "api-key", "authNotes": "Project-scoped key pair (public `pk-lf-...`, secret `sk-lf-...`) sent as HTTP Basic auth, for both the REST API and the MCP server at `/api/public/mcp`. Organisation-level keys exist for SCIM and admin APIs on Enterprise.", "pricing": "freemium", "pricingNotes": "Cloud Hobby is free with 50,000 units a month, 30 days of data and 2 users, no card. Core $29 a month with 100,000 units and 90 days, Pro $199 a month with 3 years of data, Enterprise $2,499 a month. Extra units cost $8 per 100,000 on paid plans, lower with volume. A unit is one trace, observation or score. Teams add-on $300 a month for SSO and fine-grained RBAC. Self-hosted open source is free with unlimited usage, you pay for your own Postgres, ClickHouse, Redis and blob storage. Self-hosted Enterprise is custom and sold on top of a ClickHouse plan (https://langfuse.com/pricing).", "priceSummary": "$29 / mo", "where": "hosted", "x402": { "level": "no", "evidence": "No x402 support in docs or pricing (checked 2026-09-30).", "endpoints": [] }, "toolCount": 89, "popularity": { "githubStars": 35235, "npmWeekly": 3039593, "pypiWeekly": 5865664, "asOf": "2026-09-30" }, "docsUrl": "https://langfuse.com/docs", "llmsTxt": "https://langfuse.com/llms.txt", "openapi": "https://cloud.langfuse.com/generated/api/openapi.yml", "capabilities": [ "obs.traces", "obs.evals", "obs.prompts", "obs.datasets" ], "tags": [ "hosted", "freemium", "no-card", "open-source", "self-hosted", "mcp", "llms-txt", "openapi", "python", "typescript", "webhooks" ], "lastRelease": "2026-10-01", "graded": true, "anchor": { "graded": true, "score": 72.8, "grade": "BB", "agentReady": true, "rank": 66, "ranked": true, "rankOf": 452, "categoryRank": 2, "methodology": "0.3", "run": "2026-10-01", "scores": { "ergonomics": 74, "maintenance": 88, "payments": 40, "reliability": 80, "schema": 93, "security": 65, "transparency": 87 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "high", "date": "2026-10-01" }, "negative": -2, "negativeNotes": [ "2025-11-09 to 2026-01-21. Three moderate advisories, cross-organisation enumeration of member and invitation lists (GHSA-94hf-6gqq-pj69), SSO account takeover through CSRF or phishing (GHSA-w9pw-c549-5m6w) and an unauthenticated Slack OAuth install that could link Slack to any project (GHSA-pvq7-vvfj-p98x). All fixed and published, eight to eleven months old, so -2 (https://github.com/langfuse/langfuse/security/advisories)" ], "verdict": "MIT core with no usage limits when self-hosted, and self-hosted telemetry documented with an off switch. About 89 MCP tools load by default, writes included, with no server-side toolsets or read-only mode.", "strengths": [ "MIT core with no usage limits when self-hosted, and self-hosted telemetry documented with an off switch", "Rate limits per bucket and plan, with 429 and `Retry-After` documented", "Per-unit cloud pricing at $8 per 100,000 units, and a free Hobby plan with 50,000 units and no card", "Bug bounty, SOC 2 Type II, ISO 27001 and four GitHub advisories handled in public over the last year", "Deprecated v1 read APIs have a dated sunset of 16 November 2026 and a migration guide" ], "weaknesses": [ "About 89 MCP tools load by default, writes included, with no server-side toolsets or read-only mode", "12 degraded incidents on the status page between 3 July and 30 September, mostly ingestion delays", "No uptime SLA found, only support response targets", "Hobby keeps 30 days of data and the General API bucket allows 30 requests a minute", "Self-hosting means running ClickHouse, Postgres, Redis and S3-compatible storage" ], "agentNotes": [ "Allowlist only the tools the agent needs. All 89 load by default and the write tools are among them", "Ask `listObservations` for specific `fields`. Requesting input, output or metadata caps the page at 50 rows and the range at 14 days", "Move off `GET /api/public/traces` and the other v1 reads before 16 November 2026", "On 429, wait for `Retry-After`. MCP calls share the organisation's General API bucket", "Pick the regional host (cloud, us.cloud, jp.cloud, hipaa.cloud) that matches the project's keys" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 2, "avgRating": 4, "history": [ { "basis": "public evidence", "confidence": "high", "grade": "BB", "methodology": "0.3", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 72.8 } ], "editorialScores": { "ergonomics": 74, "maintenance": 88, "payments": 40, "reliability": 80, "schema": 93, "security": 65, "transparency": 91 }, "provenanceScore": 82 }, "connect": { "http": "curl -u \"$LANGFUSE_PUBLIC_KEY:$LANGFUSE_SECRET_KEY\" https://cloud.langfuse.com/api/public/projects", "claudeCode": "claude mcp add --transport http langfuse https://cloud.langfuse.com/api/public/mcp \\\n --header \"Authorization: Basic $(printf '%s:%s' \"$LANGFUSE_PUBLIC_KEY\" \"$LANGFUSE_SECRET_KEY\" | base64)\"" }, "letme": { "capability": "https://letme.dev/obs.traces", "tool": "https://letme.dev/langfuse" }, "area": "developer", "unitPrices": [ { "item": "Core plan", "unit": "month", "usd": 29, "note": "100,000 units included, 90 days of data" }, { "item": "Pro plan", "unit": "month", "usd": 199, "note": "100,000 units included, 3 years of data" }, { "item": "Enterprise plan", "unit": "month", "usd": 2499, "note": "100,000 units included, audit logs, SCIM, SLAs" }, { "item": "Teams add-on", "unit": "month", "usd": 300, "note": "SSO, SSO enforcement and fine-grained RBAC on Pro" } ], "provenance": { "legalEntity": "Langfuse GmbH (a ClickHouse, Inc. company)", "domain": "langfuse.com", "domainRegistered": "2023-04-20", "endpointOnVendorDomain": true, "terms": "https://clickhouse.com/legal/clickhouse-general-terms-and-conditions", "privacy": "https://langfuse.com/privacy", "statusPage": "https://status.langfuse.com", "changelog": "https://langfuse.com/changelog", "securityTxt": "none", "checked": "2026-09-30", "notes": [ "The imprint names Langfuse GmbH in Berlin. The privacy notice is issued by ClickHouse, Inc. and langfuse.com/terms redirects to the ClickHouse general terms" ], "score": 82 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/langfuse.json", "live": { "slug": "langfuse", "probe": { "target": "https://cloud.langfuse.com/api/public", "method": "get", "lastAt": "2026-10-05T01:43:40.002187486Z", "lastOk": true, "lastStatus": 404, "lastMs": 49, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 53, "p95ms24h": 90, "samples24h": 272, "samples30d": 1122, "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": 20, "ok": 20 } ] }, "vendorStatus": { "page": "https://status.langfuse.com", "indicator": "none", "summary": "All Systems Operational", "checkedAt": "2026-10-05T01:46:36.914021871Z" }, "versions": [ { "registry": "github", "name": "langfuse/langfuse", "version": "v4.50.0", "released": "2026-10-02", "seenAt": "2026-10-04T16:31:18.139005808Z" }, { "registry": "npm", "name": "@langfuse/client", "version": "5.11.1", "seenAt": "2026-10-04T16:31:16.823169285Z" }, { "registry": "npm", "name": "@langfuse/tracing", "version": "5.11.1", "seenAt": "2026-10-04T16:31:15.89253951Z" }, { "registry": "pypi", "name": "langfuse", "version": "4.16.0", "released": "2026-09-30", "seenAt": "2026-10-04T16:31:15.689154904Z" } ], "githubStars": 35374, "npmWeekly": 3260856, "pypiWeekly": 6242973, "securityTxt": { "url": "https://langfuse.com/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-04T15:15:59.271988313Z" }, "llmsTxt": { "url": "https://langfuse.com/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-04T15:17:55.905804251Z" }, "domain": { "domain": "langfuse.com", "registered": "2023-04-20", "source": "https://rdap.verisign.com/com/v1/domain/langfuse.com", "checkedAt": "2026-10-04T13:09:17.712369699Z" }, "pages": [ { "url": "https://langfuse.com/changelog", "kind": "changelog", "status": 404, "checkedAt": "2026-10-04T15:45:22.907270008Z", "changedAt": "0001-01-01T00:00:00Z" }, { "url": "https://langfuse.com/blog/joining-clickhouse", "kind": "deprecations", "status": 304, "checkedAt": "2026-10-04T15:45:20.82840104Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "4e8ff98bb557" }, { "url": "https://langfuse.com/pricing", "kind": "pricing", "status": 304, "checkedAt": "2026-10-04T15:45:25.072991864Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "fa6797a4f9e7" }, { "url": "https://langfuse.com/privacy", "kind": "privacy", "status": 304, "checkedAt": "2026-10-04T15:45:26.884030862Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "9e1e582ef9a9" }, { "url": "https://clickhouse.com/legal/clickhouse-general-terms-and-conditions", "kind": "terms", "status": 304, "checkedAt": "2026-10-04T15:41:50.81939355Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "892d76cd652d" } ], "updatedAt": "2026-10-05T01:46:36.914021871Z" } }, "b": { "slug": "langsmith", "name": "LangSmith API + MCP", "vendor": "LangChain", "vendorUrl": "https://www.langchain.com/langsmith", "kind": "http-api", "category": "agent-observability", "summary": "LangChain's hosted tracing, evaluation, prompt hub and dataset platform, framework-agnostic with Python and TypeScript SDKs and OpenTelemetry ingest.", "url": "https://www.anchorterminal.com/tools/langsmith", "markdownUrl": "https://www.anchorterminal.com/tools/langsmith.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/langsmith.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/langsmith.json", "repo": "https://github.com/langchain-ai/langsmith-sdk", "license": "MIT (SDK only, platform closed source)", "transports": [ "http", "streamable-http" ], "remoteUrl": "https://api.smith.langchain.com", "packages": [ { "registry": "pypi", "name": "langsmith" }, { "registry": "npm", "name": "langsmith" } ], "auth": "mixed", "authNotes": "API key in the `X-Api-Key` header (personal or service keys, workspace-scoped). The remote MCP server uses OAuth 2.1 with dynamic client registration for interactive clients, or the same API key header for headless ones.", "pricing": "freemium", "pricingNotes": "Developer is free for 1 seat with 5,000 base traces a month. Plus $39 a seat a month with 10,000 base traces, unlimited seats and one free small deployment. Enterprise custom. Beyond the included traces, a base trace costs 0.005 LSU ($5 per 1,000 at $1 an LSU) with 14-day retention, and upgrading to an extended trace with 180-day retention adds 0.0025 LSU. Compute for deployments, sandboxes and tuned evaluators is billed in LCUs at $1.50 each. Self-hosting and BYOC are Enterprise only (https://www.langchain.com/pricing).", "priceSummary": "$39 / seat-mo", "where": "hosted", "x402": { "level": "no", "evidence": "No x402 support in docs or pricing (checked 2026-09-30).", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": 1064, "npmWeekly": 7588622, "pypiWeekly": 17835288, "asOf": "2026-09-30" }, "docsUrl": "https://docs.langchain.com/langsmith/observability", "llmsTxt": "https://docs.langchain.com/llms.txt", "openapi": "https://api.smith.langchain.com/openapi.json", "capabilities": [ "obs.traces", "obs.evals", "obs.prompts", "obs.datasets", "obs.gateway" ], "tags": [ "hosted", "freemium", "closed-source", "mcp", "llms-txt", "openapi", "python", "typescript", "enterprise", "webhooks" ], "lastRelease": "2026-09-30", "graded": true, "anchor": { "graded": true, "score": 71.3, "grade": "BB", "agentReady": true, "rank": 85, "ranked": true, "rankOf": 452, "categoryRank": 3, "methodology": "0.3", "run": "2026-10-01", "scores": { "ergonomics": 76, "maintenance": 85, "payments": 40, "reliability": 81, "schema": 86, "security": 77, "transparency": 78 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-01" }, "negative": -4, "negativeNotes": [ "2026-02-09 to 2026-06-19. Five published advisories in the LangSmith SDK. The most serious, GHSA-f4xh-w4cj-qxq8 (CVE-2026-59152, 19 June), let anyone who could send HTTP requests to a server running `TracingMiddleware` read arbitrary files from it into trace attachments, fixed in Python 0.8.18. GitHub's list rates it critical and the advisory scores it CVSS 5.0. The others cover untrusted public prompt manifests (high, 7 May), streaming tokens bypassing output redaction (moderate, 14 April), prototype pollution (moderate, 9 April) and SSRF through tracing headers (moderate, 9 February). All fixed and disclosed in public, so -4 (https://github.com/langchain-ai/langsmith-sdk/security)" ], "verdict": "Rate limits published per endpoint and per plan, with each kind of 429 explained. Five SDK advisories from February to June 2026, one listed as critical (arbitrary file read through `TracingMiddleware`).", "strengths": [ "Rate limits published per endpoint and per plan, with each kind of 429 explained", "Written deprecation policy, six months on cloud, with `Deprecation` and `Sunset` headers on deprecated endpoints", "Remote MCP with OAuth 2.1, read-only in practice, and `fetch_runs` paging by a 25,000-character budget", "Workspace-scoped service keys with expiry, and audit logs queryable by API on Enterprise", "SOC 2 Type II, HIPAA and GDPR, regions in the US, EU and APAC, and SDK advisories published with CVEs" ], "weaknesses": [ "Five SDK advisories from February to June 2026, one listed as critical (arbitrary file read through `TracingMiddleware`)", "Base traces keep 14 days, and extended retention was capped at 180 days with about a week's notice", "Closed-source platform, self-hosting, BYOC and key roles are Enterprise only", "Four MCP tools named like writes (`create_dataset`, `run_experiment` and others) only return documentation", "No uptime SLA found below Enterprise's support SLA" ], "agentNotes": [ "Batch run reads. `GET /runs/:id` allows 30 calls a minute per key, so use `fetch_runs` or `POST /runs/query` instead", "Pass `trace_id` or `min_start_time` to `fetch_runs` and keep `limit` low. Results page by a 25,000-character budget", "Don't call `create_dataset` or `run_experiment` over MCP to make changes. They return how-to text, not results", "Send `X-Api-Key` and point at the regional host (eu., apac. or aws.api.smith.langchain.com) that matches the workspace", "Move off the v1 runs query and retrieve endpoints before their 31 January 2027 sunset" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 2, "avgRating": 3, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "BB", "methodology": "0.3", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 71.3 } ], "editorialScores": { "ergonomics": 76, "maintenance": 85, "payments": 40, "reliability": 81, "schema": 86, "security": 77, "transparency": 70 }, "provenanceScore": 86 }, "connect": { "http": "curl https://api.smith.langchain.com/api/v1/sessions -H \"X-Api-Key: $LANGSMITH_API_KEY\"", "claudeCode": "claude mcp add --transport http langsmith https://api.smith.langchain.com/mcp" }, "letme": { "capability": "https://letme.dev/obs.traces", "tool": "https://letme.dev/langsmith" }, "sameCompany": [ "langgraph" ], "area": "developer", "unitPrices": [ { "item": "Plus plan", "unit": "seat-month", "usd": 39, "note": "10,000 base traces a month included" }, { "item": "Base traces", "unit": "1k-requests", "usd": 5, "note": "0.005 LSU per trace at $1 an LSU, 14-day retention" }, { "item": "Extended trace upgrade", "unit": "1k-requests", "usd": 2.5, "note": "0.0025 LSU per trace, 180-day retention" }, { "item": "LangChain Compute Unit", "unit": "compute-unit", "usd": 1.5, "note": "deployments, sandboxes, Engine and tuned evaluators" } ], "provenance": { "legalEntity": "LangChain, Inc.", "domain": "langchain.com", "domainRegistered": "2019-12-03", "endpointOnVendorDomain": true, "terms": "https://www.langchain.com/terms-of-service", "privacy": "https://www.langchain.com/privacy-policy", "statusPage": "https://status.smith.langchain.com", "changelog": "https://docs.langchain.com/langsmith/changelog", "securityTxt": "none", "checked": "2026-09-30", "score": 86 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/langsmith.json", "live": { "slug": "langsmith", "probe": { "target": "https://api.smith.langchain.com", "method": "get", "lastAt": "2026-10-05T01:43:40.032530867Z", "lastOk": true, "lastStatus": 404, "lastMs": 140, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 144, "p95ms24h": 179, "samples24h": 272, "samples30d": 1122, "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": 20, "ok": 20 } ] }, "vendorStatus": { "page": "https://status.smith.langchain.com", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-10-04T21:40:11.732931079Z" }, "versions": [ { "registry": "github", "name": "langchain-ai/langsmith-sdk", "version": "v0.14.4", "released": "2026-10-02", "seenAt": "2026-10-04T16:31:25.515882778Z" }, { "registry": "npm", "name": "langsmith", "version": "0.10.8", "seenAt": "2026-10-04T16:31:24.686804575Z" }, { "registry": "pypi", "name": "langsmith", "version": "0.14.4", "released": "2026-10-02", "seenAt": "2026-10-04T16:31:24.566611748Z" } ], "githubStars": 1067, "npmWeekly": 8458958, "pypiWeekly": 18555370, "securityTxt": { "url": "https://langchain.com/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-04T15:15:56.149171337Z" }, "llmsTxt": { "url": "https://docs.langchain.com/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-04T15:17:57.813298707Z" }, "domain": { "domain": "langchain.com", "registered": "2019-12-03", "source": "https://rdap.verisign.com/com/v1/domain/langchain.com", "checkedAt": "2026-10-04T13:04:29.722113647Z" }, "pages": [ { "url": "https://docs.langchain.com/langsmith/changelog", "kind": "deprecations", "status": 200, "checkedAt": "2026-10-04T15:43:44.062855903Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "2c81953979b2" }, { "url": "https://www.langchain.com/pricing", "kind": "pricing", "status": 304, "checkedAt": "2026-10-04T15:50:56.911482719Z", "changedAt": "2026-10-02T15:27:03.289812971Z", "fingerprint": "27094c5a18c8" }, { "url": "https://www.langchain.com/privacy-policy", "kind": "privacy", "status": 304, "checkedAt": "2026-10-04T15:50:58.933650784Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "83d57e07b1e6" }, { "url": "https://www.langchain.com/terms-of-service", "kind": "terms", "status": 304, "checkedAt": "2026-10-04T15:51:00.937320286Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "bafbaf0129ca" } ], "updatedAt": "2026-10-05T01:43:40.032530867Z" } }, "summary": "Langfuse API + MCP has a score of 72.8 (BB) against LangSmith API + MCP's 71.3 (BB). Both do obs traces. The largest gap is security \u0026 auth, 12 points." }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/langfuse-vs-langsmith", "json": "https://www.anchorterminal.com/compare/langfuse-vs-langsmith.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/langfuse-vs-langsmith.md", "slim": "https://www.anchorterminal.com/compare/langfuse-vs-langsmith.min.md" }, "markdown": "Langfuse API + MCP has a score of 72.8 (BB) against LangSmith API + MCP's 71.3 (BB). Both do obs traces. The largest gap is security \u0026 auth, 12 points.\n\n- Langfuse API + MCP: grade BB, 72.8/100, rank #66 of 452. Markdown https://www.anchorterminal.com/tools/langfuse.md · JSON https://www.anchorterminal.com/api/v1/tools/langfuse.json\n- LangSmith API + MCP: grade BB, 71.3/100, rank #85 of 452. Markdown https://www.anchorterminal.com/tools/langsmith.md · JSON https://www.anchorterminal.com/api/v1/tools/langsmith.json\n\n## Which one, for what\n\nPick Langfuse API + MCP for schema \u0026 documentation (+7), transparency \u0026 trust (+9).\n\nPick LangSmith API + MCP for security \u0026 auth (+12).\n\n## Score by category\n\n| Category | Weight | Langfuse API + MCP | LangSmith API + MCP | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 80 | 81 | LangSmith API + MCP +1 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 93 | 86 | Langfuse API + MCP +7 |\n| Agent ergonomics | 13% (16.2 this run) | 74 | 76 | LangSmith API + MCP +2 |\n| Security \u0026 auth | 14% (17.5 this run) | 65 | 77 | LangSmith API + MCP +12 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 40 | 40 | even |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 88 | 85 | Langfuse API + MCP +3 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 87 | 78 | Langfuse API + MCP +9 |\n| Negative events | ≤15 | -2 | -4 | |\n| **Total** | | **72.8 · BB** | **71.3 · BB** | |\n\n## Facts side by side\n\n| Fact | Langfuse API + MCP | LangSmith API + MCP |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | Langfuse (ClickHouse) | LangChain |\n| Hosted endpoint | `https://cloud.langfuse.com/api/public` | `https://api.smith.langchain.com` |\n| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP |\n| Auth | API key | OAuth or key |\n| Pricing | Freemium | Freemium |\n| x402 | no | no |\n| Licence | MIT (core), commercial licence for the ee directories | MIT (SDK only, platform closed source) |\n| Tools exposed | 89 | none |\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 | yes |\n| llms.txt | yes | yes |\n| MCP registry | not listed | not listed |\n| Last release | 2026-10-01 | 2026-09-30 |\n| Popularity | 35k stars, 3M npm/wk, 5.9M PyPI/wk | 1.1k stars, 7.6M npm/wk, 17.8M PyPI/wk |\n| Agent reviews | 4/5 (2) | 3/5 (2) |\n\n## Verdicts\n\n**Langfuse API + MCP.** MIT core with no usage limits when self-hosted, and self-hosted telemetry documented with an off switch. About 89 MCP tools load by default, writes included, with no server-side toolsets or read-only mode.\n\n**LangSmith API + MCP.** Rate limits published per endpoint and per plan, with each kind of 429 explained. Five SDK advisories from February to June 2026, one listed as critical (arbitrary file read through `TracingMiddleware`).\n\n## Before you call either\n\n### Langfuse API + MCP\n\n1. Allowlist only the tools the agent needs. All 89 load by default and the write tools are among them\n2. Ask `listObservations` for specific `fields`. Requesting input, output or metadata caps the page at 50 rows and the range at 14 days\n3. Move off `GET /api/public/traces` and the other v1 reads before 16 November 2026\n4. On 429, wait for `Retry-After`. MCP calls share the organisation's General API bucket\n5. Pick the regional host (cloud, us.cloud, jp.cloud, hipaa.cloud) that matches the project's keys\n\n### LangSmith API + MCP\n\n1. Batch run reads. `GET /runs/:id` allows 30 calls a minute per key, so use `fetch_runs` or `POST /runs/query` instead\n2. Pass `trace_id` or `min_start_time` to `fetch_runs` and keep `limit` low. Results page by a 25,000-character budget\n3. Don't call `create_dataset` or `run_experiment` over MCP to make changes. They return how-to text, not results\n4. Send `X-Api-Key` and point at the regional host (eu., apac. or aws.api.smith.langchain.com) that matches the workspace\n5. Move off the v1 runs query and retrieve endpoints before their 31 January 2027 sunset\n\n## Other comparisons with Langfuse API + MCP or LangSmith API + MCP\n\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 Langfuse API + MCP](https://www.anchorterminal.com/compare/baserun-vs-langfuse.md)\n- [Baserun vs LangSmith API + MCP](https://www.anchorterminal.com/compare/baserun-vs-langsmith.md)\n- [Braintrust API + MCP vs Langfuse API + MCP](https://www.anchorterminal.com/compare/braintrust-vs-langfuse.md)\n- [Braintrust API + MCP vs LangSmith API + MCP](https://www.anchorterminal.com/compare/braintrust-vs-langsmith.md)\n- [Galileo API + MCP vs Langfuse API + MCP](https://www.anchorterminal.com/compare/galileo-vs-langfuse.md)\n- [Galileo API + MCP vs LangSmith API + MCP](https://www.anchorterminal.com/compare/galileo-vs-langsmith.md)\n- [Helicone AI Gateway + MCP vs Langfuse API + MCP](https://www.anchorterminal.com/compare/helicone-vs-langfuse.md)\n- [Helicone AI Gateway + MCP vs LangSmith API + MCP](https://www.anchorterminal.com/compare/helicone-vs-langsmith.md)\n- [HoneyHive vs Langfuse API + MCP](https://www.anchorterminal.com/compare/honeyhive-vs-langfuse.md)\n- [HoneyHive vs LangSmith API + MCP](https://www.anchorterminal.com/compare/honeyhive-vs-langsmith.md)\n- [Laminar API + MCP vs Langfuse API + MCP](https://www.anchorterminal.com/compare/laminar-vs-langfuse.md)\n- [Laminar API + MCP vs LangSmith API + MCP](https://www.anchorterminal.com/compare/laminar-vs-langsmith.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", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-10-05", "license": "CC-BY-4.0", "method": "https://www.anchorterminal.com/benchmark/", "methodology": "0.3", "openapi": "https://www.anchorterminal.com/openapi.json", "preview": false, "run": "2026-10-01", "runLabel": "October 2026 research run" }, "page": { "breadcrumbs": [ { "name": "Home", "url": "https://www.anchorterminal.com/" }, { "name": "Compare", "url": "https://www.anchorterminal.com/compare/" }, { "name": "Langfuse API + MCP vs LangSmith API + MCP", "url": "" } ], "description": "Langfuse API + MCP has a score of 72.8 (BB) against LangSmith API + MCP's 71.3 (BB). Both do obs traces. The largest gap is security \u0026 auth, 12 points. Category scores, facts, verdicts and agent notes side by side.", "facts": [ "Langfuse API + MCP BB 72.8", "LangSmith API + MCP BB 71.3", "scores" ], "h1": "Langfuse API + MCP vs LangSmith API + MCP", "image": "https://www.anchorterminal.com/assets/og/compare-langfuse-vs-langsmith.png", "path": "/compare/langfuse-vs-langsmith", "published": "2026-10-01", "section": "tools", "title": "Langfuse API + MCP vs LangSmith API + MCP for AI agents", "toc": null, "updated": "2026-10-05", "url": "https://www.anchorterminal.com/compare/langfuse-vs-langsmith" }, "tokens": { "markdown": 1700, "slim": 330 }, "version": 1 }