{ "data": { "a": { "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": 71.1, "grade": "BB", "agentReady": true, "rank": 131, "ranked": true, "rankOf": 842, "categoryRank": 3, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 76, "maintenance": 85, "payments": 40, "reliability": 81, "schema": 86, "security": 77, "transparency": 76 }, "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`).", "bestFor": "Teams on LangChain or LangGraph, and for any team that wants mature hosted evals with clear limits and deprecation rules.", "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": "0.4", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 71.1 } ], "editorialScores": { "ergonomics": 76, "maintenance": 85, "payments": 40, "reliability": 81, "schema": 86, "security": 77, "transparency": 70 }, "provenanceScore": 82 }, "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", "langmem" ], "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": 82 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/langsmith.json", "live": { "slug": "langsmith", "probe": { "target": "https://api.smith.langchain.com", "method": "get", "lastAt": "2026-10-09T10:42:47.068202433Z", "lastOk": true, "lastStatus": 404, "lastMs": 143, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 147, "p95ms24h": 177, "samples24h": 260, "samples30d": 2300, "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": 272, "ok": 272 }, { "date": "2026-10-06", "probes": 272, "ok": 272 }, { "date": "2026-10-07", "probes": 272, "ok": 272 }, { "date": "2026-10-08", "probes": 268, "ok": 268 }, { "date": "2026-10-09", "probes": 114, "ok": 114 } ] }, "vendorStatus": { "page": "https://status.smith.langchain.com", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-10-09T07:58:07.234066044Z" }, "versions": [ { "registry": "github", "name": "langchain-ai/langsmith-sdk", "version": "v0.14.4", "released": "2026-10-02", "seenAt": "2026-10-08T16:18:32.267013526Z" }, { "registry": "npm", "name": "langsmith", "version": "0.10.8", "seenAt": "2026-10-08T16:18:31.439212454Z" }, { "registry": "pypi", "name": "langsmith", "version": "0.14.4", "released": "2026-10-02", "seenAt": "2026-10-08T16:18:31.228610924Z" } ], "githubStars": 1070, "npmWeekly": 8568634, "pypiWeekly": 19080233, "securityTxt": { "url": "https://langchain.com/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-08T15:39:09.255420267Z" }, "llmsTxt": { "url": "https://docs.langchain.com/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-08T14:00:35.905310918Z" }, "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": "2026-10-08T18:18:53.012390126Z", "changedAt": "2026-10-06T16:08:16.420087518Z", "fingerprint": "27f69d5d313f" }, { "url": "https://www.langchain.com/pricing", "kind": "pricing", "status": 304, "checkedAt": "2026-10-08T18:28:39.230378914Z", "changedAt": "2026-10-02T15:27:03.289812971Z", "fingerprint": "27094c5a18c8" }, { "url": "https://www.langchain.com/privacy-policy", "kind": "privacy", "status": 304, "checkedAt": "2026-10-08T18:28:41.285966958Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "83d57e07b1e6" }, { "url": "https://www.langchain.com/terms-of-service", "kind": "terms", "status": 304, "checkedAt": "2026-10-08T18:28:43.295932145Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "bafbaf0129ca" } ], "updatedAt": "2026-10-09T10:42:47.068202433Z" } }, "answer": "LangSmith API + MCP scores 71.1 (BB) on agent readiness against LangWatch's 65.5 (B), and leads in 4 of 7 scored categories. LangWatch leads on maintenance \u0026 community.", "b": { "slug": "langwatch", "name": "LangWatch", "vendor": "Reasoning Engine B.V. (LangWatch)", "vendorUrl": "https://langwatch.ai", "kind": "http-api", "category": "agent-observability", "summary": "LangWatch is an open-source platform for tracing, evaluating and testing LLM applications and agents, with prompt management, datasets and an AI gateway. It runs hosted or self-hosted, with a REST API, SDKs, a CLI and an MCP server.", "url": "https://www.anchorterminal.com/tools/langwatch", "markdownUrl": "https://www.anchorterminal.com/tools/langwatch.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/langwatch.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/langwatch.json", "repo": "https://github.com/langwatch/langwatch", "license": "Apache 2.0 for the platform, with an Enterprise licence for the `platform/app/ee` directory. The SDKs and the MCP server are MIT", "transports": [ "http", "streamable-http", "sse", "stdio" ], "remoteUrl": "https://app.langwatch.ai", "packages": [ { "registry": "npm", "name": "langwatch" }, { "registry": "npm", "name": "@langwatch/mcp-server" }, { "registry": "pypi", "name": "langwatch" } ], "auth": "mixed", "authNotes": "A person signs up at app.langwatch.ai and creates keys under Settings, API Keys, with no review step. API keys (`sk-lw-`) go in `X-Auth-Token` or as a Bearer token. A personal key never exceeds its owner's permissions, a service key belongs to the organisation and only admins create one. Either can be All or Restricted to read or write per permission category, scoped to projects, teams or the organisation, given an expiry and revoked. Ingestion keys (`ik-lw-`) can only write traces to one project. The remote MCP server uses OAuth authorisation code with PKCE and dynamic client registration. The CLI logs in with a device code approved in a browser.", "pricing": "freemium", "pricingNotes": "The Developer plan is free with no card and includes 50,000 events a month, 2 users and 3 scenarios, so an agent can start without a contract once a person has signed up. Growth is 29 euros per core seat a month with 200,000 events, then 5 euros per 100,000 events and 3 euros per GB kept beyond the included retention. Enterprise is sold through sales. Instant Evals cost $0.0546 per million input tokens, with a $1 budget on unpaid organisations. The pricing page has a currency switch and we read the euro prices only. Self-hosting under Apache 2.0 is free with no volume cap, and an Enterprise licence is priced per seat (https://langwatch.ai/pricing, https://langwatch.ai/docs/pricing.md).", "priceSummary": "Freemium", "where": "both", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the docs index, the OpenAPI document or the pricing page (checked 2026-10-09).", "endpoints": [] }, "toolCount": 101, "popularity": { "githubStars": 4925, "npmWeekly": 50105, "pypiWeekly": 87325, "asOf": "2026-10-09" }, "docsUrl": "https://langwatch.ai/docs/introduction", "llmsTxt": "https://langwatch.ai/docs/llms.txt", "openapi": "https://app.langwatch.ai/api/gateway/v1/openapi.json", "capabilities": [ "obs.traces", "obs.evals", "obs.prompts", "obs.datasets", "obs.gateway" ], "tags": [ "hosted", "freemium", "no-card", "open-source", "self-hosted", "mcp", "oauth", "llms-txt", "openapi", "opentelemetry", "python", "typescript", "go", "cli", "status-page", "eu-hosted" ], "lastRelease": "2026-10-02", "graded": true, "anchor": { "graded": true, "score": 65.5, "grade": "B", "agentReady": false, "rank": 291, "ranked": true, "rankOf": 842, "categoryRank": 7, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 67, "maintenance": 90, "payments": 40, "reliability": 53, "schema": 87, "security": 71, "transparency": 75 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-09" }, "negative": -2, "negativeNotes": [ "2026-08-19. Advisory GHSA-h25p-f8f6-2ccf, rated moderate. The standalone HTTP mode of `@langwatch/mcp-server` 0.7.0 to 1.0.0 authorised requests by session id alone and accepted an API key in the URL. Fixed in 2.0.0 on 7 August 2026 and flagged as a breaking change. The advisory says the default stdio mode and the hosted handler were never affected, so -2 (https://github.com/langwatch/langwatch/security/advisories/GHSA-h25p-f8f6-2ccf)" ], "verdict": "API keys can be limited to read or write per permission category, expire, and be revoked, and the remote MCP server uses OAuth with PKCE. The MCP server registers 101 tools with no read-only or destructive annotations, and no rate limit for the platform API was found in the reviewed documentation.", "bestFor": "Teams that want tracing, evaluations and simulated-user agent tests in one open-source product, hosted in the EU or self-hosted, and that drive it from a coding assistant through MCP or the CLI.", "strengths": [ "API keys take read or write per permission category, a project, team or organisation scope and an expiry. Ingestion keys can only write traces", "A public OpenAPI 3.1 document covers 328 operations and is served without a key, with llms.txt and a Markdown twin of every docs page", "Apache 2.0 platform with MIT SDKs and MCP server. Self-hosting has no volume cap, and every outbound call is documented with its off switch", "The free Developer plan needs no card and includes 50,000 events a month. Paid usage is published at 5 euros per 100,000 events", "Platform 3.20.1 shipped on 2 October 2026, with 21 platform releases dated since 11 July in the repository changelog" ], "weaknesses": [ "The MCP server registers 101 tools, deletes and key creation among them, with no toolsets and no `readOnlyHint` or `destructiveHint` annotations in the source", "No request rate limit for the platform API was found in the reviewed documentation. Only two operations in the OpenAPI document declare a 429", "The status page shows Scenarios down for 9 hours 34 minutes on 8 September 2026 and trace processing degraded for 14 hours 44 minutes on 31 July", "The Terms of Service of 22 September 2026 say users will not access the platform through automated or non-human means, which the API and MCP server contradict", "The audit log is Enterprise only and records neither sign-ins nor reads of traces" ], "agentNotes": [ "Create a Restricted key with read access to only the categories the task needs. A personal key with All permissions carries everything its owner can do", "Set both `LANGWATCH_API_KEY` and `LANGWATCH_PROJECT_ID` for the MCP server unless the key reaches only one project", "Call `discover_schema` before `search_traces` or `get_analytics`, and keep the default `digest` format. `json` returns the full raw trace", "Allowlist MCP tools in the client. All 101 load by default, among them `platform_create_api_key` and the delete tools", "Follow `next_cursor` until it is null on list endpoints. A full page does not mean more rows exist" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 0, "avgRating": 0, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "B", "methodology": "0.4", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 65.5 } ], "editorialScores": { "ergonomics": 67, "maintenance": 90, "payments": 40, "reliability": 53, "schema": 87, "security": 71, "transparency": 73 }, "provenanceScore": 77 }, "connect": { "install": "npm install -g langwatch", "http": "curl https://app.langwatch.ai/api/gateway/v1/openapi.json", "claudeCode": "claude mcp add langwatch --env LANGWATCH_API_KEY=sk-lw-... --env LANGWATCH_PROJECT_ID=your-project-id -- npx -y @langwatch/mcp-server", "config": { "mcpServers": { "langwatch": { "args": [ "-y", "@langwatch/mcp-server" ], "command": "npx", "env": { "LANGWATCH_API_KEY": "sk-lw-...", "LANGWATCH_PROJECT_ID": "your-project-id" } } } } }, "letme": { "capability": "https://letme.dev/obs.traces", "tool": "https://letme.dev/langwatch" }, "area": "developer", "unitPrices": [ { "item": "Instant Evals, judge input tokens", "unit": "1m-tokens", "usd": 0.0546, "note": "Output is free. Unpaid organisations have a $1 budget in total" } ], "provenance": { "legalEntity": "Reasoning Engine B.V. (doing business as LangWatch)", "domain": "langwatch.ai", "domainRegistered": "2023-09-17", "endpointOnVendorDomain": true, "terms": "https://langwatch.ai/legal/terms-conditions", "privacy": "https://langwatch.ai/legal/privacy-policy", "statusPage": "https://status.langwatch.ai", "changelog": "https://langwatch.ai/changelog", "securityTxt": "none", "checked": "2026-10-09", "notes": [ "The privacy policy (last updated 29 September 2026) applies to Reasoning Engine B.V., doing business as LangWatch, and covers the website and the Cloud Service. The Terms of Service (last updated 22 September 2026) cover the platform and the on-premise product.", "The terms page names the entity as Reasoning Engines B.V. in its heading and Reasoning Engine B.V. in its definitions, gives Singel 126, Amsterdam as the registered office and Herengracht 551, Amsterdam as the contact address. The site footer reads LangWatch B.V.", "The API, the hosted MCP server and the OpenAPI document are served from app.langwatch.ai. Hosted services for self-hosted installs with a licence use connect.langwatch.ai and gateway.langwatch.ai.", "https://langwatch.ai/.well-known/security.txt returns the website's HTML shell, not a security.txt file. SECURITY.md in the repository gives security@langwatch.ai and GitHub private reporting.", "RDAP for langwatch.ai gives a registration date of 2023-09-17 and GoDaddy.com, LLC as registrar.", "The trust report and sub-processor list are on app.eu.vanta.com, whose robots.txt disallows every path, so we did not read them." ], "score": 77 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/langwatch.json", "live": { "slug": "langwatch", "probe": { "target": "https://app.langwatch.ai", "method": "get", "lastAt": "2026-10-09T10:42:47.106174669Z", "lastOk": true, "lastStatus": 200, "lastMs": 49, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 85, "p95ms24h": 135, "samples24h": 33, "samples30d": 33, "days": [ { "date": "2026-10-09", "probes": 33, "ok": 33 } ] }, "vendorStatus": { "page": "https://status.langwatch.ai", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-10-09T07:58:07.342247188Z" }, "updatedAt": "2026-10-09T10:42:47.106174669Z" } }, "facts": [ { "a": "HTTP API", "b": "HTTP API", "name": "Kind" }, { "a": "LangChain", "b": "Reasoning Engine B.V. (LangWatch)", "name": "Vendor" }, { "a": "https://api.smith.langchain.com", "b": "https://app.langwatch.ai", "name": "Hosted endpoint" }, { "a": "HTTP, Streamable HTTP", "b": "HTTP, Streamable HTTP, SSE (legacy), stdio", "name": "Transports" }, { "a": "OAuth or key", "b": "OAuth or key", "name": "Auth" }, { "a": "Freemium", "b": "Freemium", "name": "Pricing" }, { "a": "$2.50 per 1,000 requests", "b": "not published", "name": "Price for obs traces" }, { "a": "no", "b": "no", "name": "x402" }, { "a": "MIT (SDK only, platform closed source)", "b": "Apache 2.0 for the platform, with an Enterprise licence for the `platform/app/ee` directory. The SDKs and the MCP server are MIT", "name": "Licence" }, { "a": "none", "b": "101", "name": "Tools exposed" }, { "a": "yes", "b": "no", "name": "Read-only variant documented" }, { "a": "yes", "b": "yes", "name": "llms.txt" }, { "a": "2026-09-30", "b": "2026-10-02", "name": "Last release" }, { "a": "2026-06-02", "b": "2026-09-22", "name": "Terms last updated" }, { "a": "2024-04-28", "b": "2026-09-29", "name": "Privacy policy last updated" }, { "a": "not found in the text", "b": "not found in the text", "name": "Customer content may train models" }, { "a": "not found in the text", "b": "yes", "name": "Terms restrict automated access" }, { "a": "yes", "b": "not found in the text", "name": "Terms restrict benchmarking" }, { "a": "not found in the text", "b": "yes", "name": "Terms or service can change without notice" }, { "a": "not found in the text", "b": "not found in the text", "name": "Arbitration or class-action waiver" }, { "a": "1.1k stars, 7.6M npm/wk, 17.8M PyPI/wk", "b": "4.9k stars, 50k npm/wk, 87k PyPI/wk", "name": "Popularity" }, { "a": "3/5 (2)", "b": "none", "name": "Agent reviews" } ], "faq": [ { "answer": "LangSmith API + MCP scores 71.1 (BB) on agent readiness against LangWatch's 65.5 (B), and leads in 4 of 7 scored categories. LangWatch leads on maintenance \u0026 community.", "question": "Which is better for AI agents, LangSmith API + MCP or LangWatch?" }, { "answer": "Both take an API key or an OAuth sign-in.", "question": "Do LangSmith API + MCP and LangWatch need an API key?" }, { "answer": "Yes. LangSmith API + MCP has a hosted endpoint at https://api.smith.langchain.com and LangWatch at https://app.langwatch.ai.", "question": "Can an agent call LangSmith API + MCP and LangWatch without installing anything?" }, { "answer": "No open-source release is listed for LangSmith API + MCP. LangWatch is open source (Apache 2.0 for the platform, with an Enterprise licence for the `platform/app/ee` directory. The SDKs and the MCP server are MIT).", "question": "Are LangSmith API + MCP and LangWatch open source?" } ], "goodFor": [ { "aheadOn": [ "Reliability, 81 against 53", "Agent ergonomics, 76 against 67", "Security \u0026 auth, 77 against 71" ], "also": [ "Agent-ready, a grade of BB or better" ], "goodFor": "Teams on LangChain or LangGraph, and for any team that wants mature hosted evals with clear limits and deprecation rules.", "slug": "langsmith", "watchFor": "Five SDK advisories from February to June 2026, one listed as critical (arbitrary file read through `TracingMiddleware`)" }, { "aheadOn": [ "Maintenance \u0026 community, 90 against 85" ], "also": [ "Runs on your own machine", "Free to start without a card", "Open source" ], "goodFor": "Teams that want tracing, evaluations and simulated-user agent tests in one open-source product, hosted in the EU or self-hosted, and that drive it from a coding assistant through MCP or the CLI.", "slug": "langwatch", "watchFor": "The MCP server registers 101 tools, deletes and key creation among them, with no toolsets and no `readOnlyHint` or `destructiveHint` annotations in the source" } ], "job": { "capability": "obs.traces", "name": "Obs traces" }, "others": [ { "json": "https://www.anchorterminal.com/compare/arize-phoenix-vs-langsmith.json", "title": "Arize Phoenix vs LangSmith API + MCP", "url": "https://www.anchorterminal.com/compare/arize-phoenix-vs-langsmith" }, { "json": "https://www.anchorterminal.com/compare/arize-phoenix-vs-langwatch.json", "title": "Arize Phoenix vs LangWatch", "url": "https://www.anchorterminal.com/compare/arize-phoenix-vs-langwatch" }, { "json": "https://www.anchorterminal.com/compare/baserun-vs-langsmith.json", "title": "Baserun vs LangSmith API + MCP", "url": "https://www.anchorterminal.com/compare/baserun-vs-langsmith" }, { "json": "https://www.anchorterminal.com/compare/baserun-vs-langwatch.json", "title": "Baserun vs LangWatch", "url": "https://www.anchorterminal.com/compare/baserun-vs-langwatch" }, { "json": "https://www.anchorterminal.com/compare/braintrust-vs-langsmith.json", "title": "Braintrust API + MCP vs LangSmith API + MCP", "url": "https://www.anchorterminal.com/compare/braintrust-vs-langsmith" }, { "json": "https://www.anchorterminal.com/compare/braintrust-vs-langwatch.json", "title": "Braintrust API + MCP vs LangWatch", "url": "https://www.anchorterminal.com/compare/braintrust-vs-langwatch" }, { "json": "https://www.anchorterminal.com/compare/galileo-vs-langsmith.json", "title": "Galileo API + MCP vs LangSmith API + MCP", "url": "https://www.anchorterminal.com/compare/galileo-vs-langsmith" }, { "json": "https://www.anchorterminal.com/compare/galileo-vs-langwatch.json", "title": "Galileo API + MCP vs LangWatch", "url": "https://www.anchorterminal.com/compare/galileo-vs-langwatch" }, { "json": "https://www.anchorterminal.com/compare/helicone-vs-langsmith.json", "title": "Helicone AI Gateway + MCP vs LangSmith API + MCP", "url": "https://www.anchorterminal.com/compare/helicone-vs-langsmith" }, { "json": "https://www.anchorterminal.com/compare/helicone-vs-langwatch.json", "title": "Helicone AI Gateway + MCP vs LangWatch", "url": "https://www.anchorterminal.com/compare/helicone-vs-langwatch" }, { "json": "https://www.anchorterminal.com/compare/honeyhive-vs-langsmith.json", "title": "HoneyHive vs LangSmith API + MCP", "url": "https://www.anchorterminal.com/compare/honeyhive-vs-langsmith" }, { "json": "https://www.anchorterminal.com/compare/honeyhive-vs-langwatch.json", "title": "HoneyHive vs LangWatch", "url": "https://www.anchorterminal.com/compare/honeyhive-vs-langwatch" }, { "json": "https://www.anchorterminal.com/compare/laminar-vs-langsmith.json", "title": "Laminar API + MCP vs LangSmith API + MCP", "url": "https://www.anchorterminal.com/compare/laminar-vs-langsmith" }, { "json": "https://www.anchorterminal.com/compare/laminar-vs-langwatch.json", "title": "Laminar API + MCP vs LangWatch", "url": "https://www.anchorterminal.com/compare/laminar-vs-langwatch" }, { "json": "https://www.anchorterminal.com/compare/langfuse-vs-langsmith.json", "title": "Langfuse API + MCP vs LangSmith API + MCP", "url": "https://www.anchorterminal.com/compare/langfuse-vs-langsmith" }, { "json": "https://www.anchorterminal.com/compare/langfuse-vs-langwatch.json", "title": "Langfuse API + MCP vs LangWatch", "url": "https://www.anchorterminal.com/compare/langfuse-vs-langwatch" }, { "json": "https://www.anchorterminal.com/compare/langsmith-vs-prefactor.json", "title": "LangSmith API + MCP vs Prefactor", "url": "https://www.anchorterminal.com/compare/langsmith-vs-prefactor" }, { "json": "https://www.anchorterminal.com/compare/langsmith-vs-respan.json", "title": "LangSmith API + MCP vs Respan API + MCP", "url": "https://www.anchorterminal.com/compare/langsmith-vs-respan" }, { "json": "https://www.anchorterminal.com/compare/langsmith-vs-wandb-weave.json", "title": "LangSmith API + MCP vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/langsmith-vs-wandb-weave" }, { "json": "https://www.anchorterminal.com/compare/langwatch-vs-prefactor.json", "title": "LangWatch vs Prefactor", "url": "https://www.anchorterminal.com/compare/langwatch-vs-prefactor" }, { "json": "https://www.anchorterminal.com/compare/langwatch-vs-respan.json", "title": "LangWatch vs Respan API + MCP", "url": "https://www.anchorterminal.com/compare/langwatch-vs-respan" }, { "json": "https://www.anchorterminal.com/compare/langwatch-vs-wandb-weave.json", "title": "LangWatch vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/langwatch-vs-wandb-weave" } ], "scores": [ { "by": 28, "edge": "langsmith", "key": "reliability", "langsmith": 81, "langwatch": 53, "name": "Reliability", "weight": 16 }, { "key": "performance", "name": "Performance", "pending": true, "weight": 10 }, { "by": 1, "edge": "langwatch", "key": "schema", "langsmith": 86, "langwatch": 87, "name": "Schema \u0026 documentation", "weight": 13 }, { "by": 9, "edge": "langsmith", "key": "ergonomics", "langsmith": 76, "langwatch": 67, "name": "Agent ergonomics", "weight": 13 }, { "by": 6, "edge": "langsmith", "key": "security", "langsmith": 77, "langwatch": 71, "name": "Security \u0026 auth", "weight": 14 }, { "by": 0, "edge": "", "key": "payments", "langsmith": 40, "langwatch": 40, "name": "Payments \u0026 pricing", "weight": 10 }, { "key": "tasks", "name": "Task success", "pending": true, "weight": 10 }, { "by": 5, "edge": "langwatch", "key": "maintenance", "langsmith": 85, "langwatch": 90, "name": "Maintenance \u0026 community", "weight": 7 }, { "by": 1, "edge": "langsmith", "key": "transparency", "langsmith": 76, "langwatch": 75, "name": "Transparency \u0026 trust", "weight": 7 } ], "summary": "LangSmith API + MCP scores 71.1 (BB) on agent readiness against LangWatch's 65.5 (B), and leads in 4 of 7 scored categories. LangWatch leads on maintenance \u0026 community. Both do obs traces.", "verdicts": { "langsmith": "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`).", "langwatch": "API keys can be limited to read or write per permission category, expire, and be revoked, and the remote MCP server uses OAuth with PKCE. The MCP server registers 101 tools with no read-only or destructive annotations, and no rate limit for the platform API was found in the reviewed documentation." } }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/langsmith-vs-langwatch", "json": "https://www.anchorterminal.com/compare/langsmith-vs-langwatch.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/langsmith-vs-langwatch.md", "slim": "https://www.anchorterminal.com/compare/langsmith-vs-langwatch.min.md" }, "markdown": "LangSmith API + MCP scores 71.1 (BB) on agent readiness against LangWatch's 65.5 (B), and leads in 4 of 7 scored categories. LangWatch leads on maintenance \u0026 community. Both do obs traces.\n\n- LangSmith API + MCP: grade BB, 71.1/100, rank #131 of 842. Markdown https://www.anchorterminal.com/tools/langsmith.md · JSON https://www.anchorterminal.com/api/v1/tools/langsmith.json\n- LangWatch: grade B, 65.5/100, rank #291 of 842. Markdown https://www.anchorterminal.com/tools/langwatch.md · JSON https://www.anchorterminal.com/api/v1/tools/langwatch.json\n\n## Which one, for what\n\n### LangSmith API + MCP (BB)\n\nGood for: Teams on LangChain or LangGraph, and for any team that wants mature hosted evals with clear limits and deprecation rules.\n\nAhead on:\n- Reliability, 81 against 53\n- Agent ergonomics, 76 against 67\n- Security \u0026 auth, 77 against 71\n\nAlso in its favour:\n- Agent-ready, a grade of BB or better\n\nWatch for: Five SDK advisories from February to June 2026, one listed as critical (arbitrary file read through `TracingMiddleware`)\n\n### LangWatch (B)\n\nGood for: Teams that want tracing, evaluations and simulated-user agent tests in one open-source product, hosted in the EU or self-hosted, and that drive it from a coding assistant through MCP or the CLI.\n\nAhead on:\n- Maintenance \u0026 community, 90 against 85\n\nAlso in its favour:\n- Runs on your own machine\n- Free to start without a card\n- Open source\n\nWatch for: The MCP server registers 101 tools, deletes and key creation among them, with no toolsets and no `readOnlyHint` or `destructiveHint` annotations in the source\n\n\n## Score by category\n\n| Category | Weight | LangSmith API + MCP | LangWatch | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 81 | 53 | LangSmith API + MCP +28 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 86 | 87 | LangWatch +1 |\n| Agent ergonomics | 13% (16.2 this run) | 76 | 67 | LangSmith API + MCP +9 |\n| Security \u0026 auth | 14% (17.5 this run) | 77 | 71 | LangSmith API + MCP +6 |\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) | 85 | 90 | LangWatch +5 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 76 | 75 | LangSmith API + MCP +1 |\n| Negative events | ≤15 | -4 | -2 | |\n| **Total** | | **71.1 · BB** | **65.5 · B** | |\n\n## Facts side by side\n\n| Fact | LangSmith API + MCP | LangWatch |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | LangChain | Reasoning Engine B.V. (LangWatch) |\n| Hosted endpoint | `https://api.smith.langchain.com` | `https://app.langwatch.ai` |\n| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP, SSE (legacy), stdio |\n| Auth | OAuth or key | OAuth or key |\n| Pricing | Freemium | Freemium |\n| Price for obs traces | $2.50 per 1,000 requests | not published |\n| x402 | no | no |\n| Licence | MIT (SDK only, platform closed source) | Apache 2.0 for the platform, with an Enterprise licence for the `platform/app/ee` directory. The SDKs and the MCP server are MIT |\n| Tools exposed | none | 101 |\n| Read-only variant documented | yes | no |\n| llms.txt | yes | yes |\n| Last release | 2026-09-30 | 2026-10-02 |\n| Terms last updated | 2026-06-02 | 2026-09-22 |\n| Privacy policy last updated | 2024-04-28 | 2026-09-29 |\n| Customer content may train models | not found in the text | not found in the text |\n| Terms restrict automated access | not found in the text | yes |\n| Terms restrict benchmarking | yes | not found in the text |\n| Terms or service can change without notice | not found in the text | yes |\n| Arbitration or class-action waiver | not found in the text | not found in the text |\n| Popularity | 1.1k stars, 7.6M npm/wk, 17.8M PyPI/wk | 4.9k stars, 50k npm/wk, 87k PyPI/wk |\n| Agent reviews | 3/5 (2) | none |\n\n## Verdicts\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**LangWatch.** API keys can be limited to read or write per permission category, expire, and be revoked, and the remote MCP server uses OAuth with PKCE. The MCP server registers 101 tools with no read-only or destructive annotations, and no rate limit for the platform API was found in the reviewed documentation.\n\n## Before you call either\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### LangWatch\n\n1. Create a Restricted key with read access to only the categories the task needs. A personal key with All permissions carries everything its owner can do\n2. Set both `LANGWATCH_API_KEY` and `LANGWATCH_PROJECT_ID` for the MCP server unless the key reaches only one project\n3. Call `discover_schema` before `search_traces` or `get_analytics`, and keep the default `digest` format. `json` returns the full raw trace\n4. Allowlist MCP tools in the client. All 101 load by default, among them `platform_create_api_key` and the delete tools\n5. Follow `next_cursor` until it is null on list endpoints. A full page does not mean more rows exist\n\n## Questions\n\n### Which is better for AI agents, LangSmith API + MCP or LangWatch?\n\nLangSmith API + MCP scores 71.1 (BB) on agent readiness against LangWatch's 65.5 (B), and leads in 4 of 7 scored categories. LangWatch leads on maintenance \u0026 community.\n\n### Do LangSmith API + MCP and LangWatch need an API key?\n\nBoth take an API key or an OAuth sign-in.\n\n### Can an agent call LangSmith API + MCP and LangWatch without installing anything?\n\nYes. LangSmith API + MCP has a hosted endpoint at https://api.smith.langchain.com and LangWatch at https://app.langwatch.ai.\n\n### Are LangSmith API + MCP and LangWatch open source?\n\nNo open-source release is listed for LangSmith API + MCP. LangWatch is open source (Apache 2.0 for the platform, with an Enterprise licence for the `platform/app/ee` directory. The SDKs and the MCP server are MIT).\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/langsmith-vs-langwatch.json, and with the fewest tokens: https://www.anchorterminal.com/compare/langsmith-vs-langwatch.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"langsmith\", \"b\": \"langwatch\"}`. From a terminal: `anchor compare langsmith langwatch`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/langsmith.json and https://www.anchorterminal.com/api/v1/tools/langwatch.json\n\n## Other comparisons with LangSmith API + MCP or LangWatch\n\n- [Arize Phoenix vs LangSmith API + MCP](https://www.anchorterminal.com/compare/arize-phoenix-vs-langsmith.md)\n- [Arize Phoenix vs LangWatch](https://www.anchorterminal.com/compare/arize-phoenix-vs-langwatch.md)\n- [Baserun vs LangSmith API + MCP](https://www.anchorterminal.com/compare/baserun-vs-langsmith.md)\n- [Baserun vs LangWatch](https://www.anchorterminal.com/compare/baserun-vs-langwatch.md)\n- [Braintrust API + MCP vs LangSmith API + MCP](https://www.anchorterminal.com/compare/braintrust-vs-langsmith.md)\n- [Braintrust API + MCP vs LangWatch](https://www.anchorterminal.com/compare/braintrust-vs-langwatch.md)\n- [Galileo API + MCP vs LangSmith API + MCP](https://www.anchorterminal.com/compare/galileo-vs-langsmith.md)\n- [Galileo API + MCP vs LangWatch](https://www.anchorterminal.com/compare/galileo-vs-langwatch.md)\n- [Helicone AI Gateway + MCP vs LangSmith API + MCP](https://www.anchorterminal.com/compare/helicone-vs-langsmith.md)\n- [Helicone AI Gateway + MCP vs LangWatch](https://www.anchorterminal.com/compare/helicone-vs-langwatch.md)\n- [HoneyHive vs LangSmith API + MCP](https://www.anchorterminal.com/compare/honeyhive-vs-langsmith.md)\n- [HoneyHive vs LangWatch](https://www.anchorterminal.com/compare/honeyhive-vs-langwatch.md)\n- [Laminar API + MCP vs LangSmith API + MCP](https://www.anchorterminal.com/compare/laminar-vs-langsmith.md)\n- [Laminar API + MCP vs LangWatch](https://www.anchorterminal.com/compare/laminar-vs-langwatch.md)\n- [Langfuse API + MCP vs LangSmith API + MCP](https://www.anchorterminal.com/compare/langfuse-vs-langsmith.md)\n- [Langfuse API + MCP vs LangWatch](https://www.anchorterminal.com/compare/langfuse-vs-langwatch.md)\n- [LangSmith API + MCP vs Prefactor](https://www.anchorterminal.com/compare/langsmith-vs-prefactor.md)\n- [LangSmith API + MCP vs Respan API + MCP](https://www.anchorterminal.com/compare/langsmith-vs-respan.md)\n- [LangSmith API + MCP vs W\u0026B Weave](https://www.anchorterminal.com/compare/langsmith-vs-wandb-weave.md)\n- [LangWatch vs Prefactor](https://www.anchorterminal.com/compare/langwatch-vs-prefactor.md)\n- [LangWatch vs Respan API + MCP](https://www.anchorterminal.com/compare/langwatch-vs-respan.md)\n- [LangWatch vs W\u0026B Weave](https://www.anchorterminal.com/compare/langwatch-vs-wandb-weave.md)\n", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-10-09", "license": "CC-BY-4.0", "method": "https://www.anchorterminal.com/benchmark/", "methodology": "0.4", "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": "LangSmith API + MCP vs LangWatch", "url": "" } ], "description": "LangSmith API + MCP scores 71.1 (BB) on agent readiness against LangWatch's 65.5 (B), and leads in 4 of 7 scored categories. LangWatch leads on maintenance \u0026 community. Both do obs traces. Category scores, facts, verdicts and agent notes side by side.", "facts": [ "LangSmith API + MCP BB 71.1", "LangWatch B 65.5", "scores" ], "h1": "LangSmith API + MCP vs LangWatch", "image": "https://www.anchorterminal.com/assets/og/compare-langsmith-vs-langwatch.png", "path": "/compare/langsmith-vs-langwatch", "published": "2026-10-01", "section": "tools", "title": "LangSmith API + MCP vs LangWatch for AI agents, BB 71.1 vs B 65.5", "toc": null, "updated": "2026-10-09", "url": "https://www.anchorterminal.com/compare/langsmith-vs-langwatch" }, "tokens": { "markdown": 2550, "slim": 730 }, "version": 1 }