{ "data": { "a": { "slug": "prefactor", "name": "Prefactor", "vendor": "Prefactor Pty Ltd", "vendorUrl": "https://prefactor.tech", "kind": "http-api", "category": "agent-observability", "summary": "Prefactor is a hosted service that records AI agent runs as spans, classifies each run's data risk and stores quality evaluations. Agents and scripts reach it through an HTTP and WebSocket API, TypeScript and Python SDKs and a CLI.", "url": "https://www.anchorterminal.com/tools/prefactor", "markdownUrl": "https://www.anchorterminal.com/tools/prefactor.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/prefactor.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/prefactor.json", "repo": "https://github.com/prefactordev/typescript-sdk", "license": "Proprietary hosted service. The TypeScript and Python SDKs and the CLI are MIT", "transports": [ "http" ], "remoteUrl": "https://app.prefactorai.com/api/v1", "packages": [ { "registry": "npm", "name": "@prefactor/core" }, { "registry": "npm", "name": "@prefactor/cli" }, { "registry": "pypi", "name": "prefactor-core" } ], "auth": "api-key", "authNotes": "Self-serve. A person signs in at app.prefactorai.com and creates an API token, sent as `Authorization: Bearer \u003ctoken\u003e`. Account tokens reach every agent in the account. Deployment tokens are bound to one agent in one environment. The OpenAPI document adds a `role` of `read_only` or `full_access` (the default) and an `expires_at` that defaults to two years. Tokens can be suspended, reactivated and revoked. `POST /api_token` mints tokens with an existing token.", "pricing": "freemium", "pricingNotes": "Free Dev plan with 5,000 spans a month, up to 3 agents and 7-day retention, no card required, so an agent's owner can start without a contract. Startup is $49 a month ($499 a year) with 15,000 spans, then $0.0025 a span. Scaleup is $199 a month ($2,000 a year) with 100,000 spans, then $2.50 per 1,000 spans monthly or $2.00 on the annual plan. Enterprise, from 4 million spans a month, is by quote. A span is one LLM call, tool call, message turn or custom step. Seats are unlimited on every plan (https://prefactor.tech/pricing).", "priceSummary": "$49 / mo", "where": "hosted", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the docs, the OpenAPI document or the pricing page (checked 2026-10-08).", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": 3, "npmWeekly": 19, "pypiWeekly": 28, "asOf": "2026-10-08" }, "docsUrl": "https://docs.prefactor.ai", "llmsTxt": "https://docs.prefactor.ai/llms.txt", "openapi": "https://app.prefactorai.com/api/v1/openapi", "capabilities": [ "obs.traces", "obs.evals" ], "tags": [ "hosted", "freemium", "no-card", "llms-txt", "openapi", "python", "typescript", "closed-source", "enterprise", "status-page" ], "lastRelease": "2026-09-13", "graded": true, "anchor": { "graded": true, "score": 65.6, "grade": "B", "agentReady": false, "rank": 286, "ranked": true, "rankOf": 842, "categoryRank": 5, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 88, "maintenance": 82, "payments": 40, "reliability": 78, "schema": 80, "security": 56, "transparency": 42 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-08" }, "negative": -3, "negativeNotes": [ "2026-10-08. The pricing page lists 'Hold, approve or block in real time' and PII detection on every plan, and the security page lists manual approval workflows and fine-grained RBAC. The vendor's own docs say crossing a risk threshold does not block or terminate a run, that Prefactor does not detect sensitive data, and that accounts have no role-based permissions. The OpenAPI and OpenRPC documents have no approval operation. Counted as a misleading claim (-3). The docs may lag the product, since the API has hosted judge operations they do not describe (https://prefactor.tech/pricing, https://prefactor.tech/security, https://docs.prefactor.ai/llms-full.txt)." ], "verdict": "The public OpenAPI document lists 157 operations, each accepting an idempotency key, and tokens can be read-only or bound to one agent deployment. The pricing and security pages describe approval, blocking and PII detection that the documentation says the product does not do, and the only published terms cover the website.", "bestFor": "A team that wants an auditable record of agent runs with declared data-risk labels, quality payloads from its own evaluations and a remote stop signal.", "strengths": [ "Public OpenAPI 3.0 document with 157 operations and an OpenRPC document with 159 WebSocket methods, both fetched without a login", "Every write accepts an `idempotency_key`, and `POST /bulk` can be retried whole because a reused key fails only its own item", "Tokens are scoped to the account or to one agent deployment, carry a `read_only` or `full_access` role and an expiry, and can be suspended or revoked", "A 429 response carries `Retry-After` and `retry_after_ms`, and both SDKs retry with exponential backoff and jitter", "The free Dev plan includes 5,000 spans a month with no card, and the overage price per span is published" ], "weaknesses": [ "The pricing page lists hold, approve or block and PII detection on every plan, while the docs say a risk threshold blocks nothing and that Prefactor does not detect sensitive data", "No approval operation exists in the OpenAPI or OpenRPC documents. The documented control is a cooperative terminate signal the agent's own code must obey", "The published terms of service cover the website. No service agreement, DPA, sub-processor list or SLA text was found", "Rate limits are described by scope with no numbers", "No security.txt and no certification held. The security page says SOC 2 Type II is in progress" ], "agentNotes": [ "Send requests to `https://app.prefactorai.com/api/v1` with `Authorization: Bearer \u003ctoken\u003e`. The API host is not on the `prefactor.tech` or `prefactor.ai` domains", "Ask for a deployment-scoped token, or an account token created with `role` set to `read_only`, since the default role is `full_access` with a two-year expiry", "Pass `redacted: true` on span list and detail queries, because the API returns marked sensitive values unless asked otherwise", "On 429 wait for `retry_after_ms`. Limits use one-minute windows and the SDKs' default retries ignore the server's hint", "Treat terminate as a request. Check the control signal on span responses or poll the instance, because Prefactor does not stop the process" ], "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": 65.6 } ], "editorialScores": { "ergonomics": 88, "maintenance": 82, "payments": 40, "reliability": 78, "schema": 80, "security": 56, "transparency": 34 }, "provenanceScore": 50 }, "connect": { "install": "npm install @prefactor/core", "http": "curl https://app.prefactorai.com/api/v1/agent \\\n -H \"Authorization: Bearer $PREFACTOR_API_TOKEN\"" }, "letme": { "capability": "https://letme.dev/obs.traces", "tool": "https://letme.dev/prefactor" }, "area": "developer", "unitPrices": [ { "item": "Startup plan", "unit": "month", "usd": 49, "note": "15,000 spans included, 3-month retention" }, { "item": "Scaleup plan", "unit": "month", "usd": 199, "note": "100,000 spans included, 12-month retention" }, { "item": "Span beyond the Startup allowance", "unit": "record", "usd": 0.0025 }, { "item": "Span beyond the Scaleup allowance", "unit": "record", "usd": 0.0025, "note": "$2.50 per 1,000 on monthly billing, $2.00 on annual" } ], "provenance": { "legalEntity": "Prefactor Pty Ltd", "domain": "prefactor.tech", "domainRegistered": "2024-10-16", "endpointOnVendorDomain": false, "terms": "", "privacy": "https://prefactor.tech/privacy-policy", "statusPage": "https://status.prefactor.ai", "changelog": "https://prefactor.tech/changelog", "securityTxt": "none", "checked": "2026-10-08", "notes": [ "prefactor.tech/llms.txt names Prefactor Pty Ltd, founded 2024, headquartered in Australia. The legal documents name the same entity and New South Wales law.", "`terms` is left out. The only published terms (last updated 17 March 2026) govern use of the website at prefactor.tech and are a generated website template. No service agreement, API terms or DPA was found on the site or in its sitemap.", "The privacy policy and terms pages are drawn by script from GetTerms. We read them from the feed the pages load (gettermscdn.com) and could render only the regional sections of the privacy policy, not its main body.", "The API answers at app.prefactorai.com, a third domain of the vendor's registered on 18 December 2025. The site is on prefactor.tech and the docs on docs.prefactor.ai.", "RDAP gives prefactor.tech a registration date of 16 October 2024 and an expiry of 16 October 2026, eight days after this check.", "prefactor.tech, app.prefactorai.com and docs.prefactor.ai each return 404 for /.well-known/security.txt. The security page asks for reports by email and promises an acknowledgement within 24 hours.", "status.prefactor.ai is an UptimeRobot page. We found no link to it on the site or docs pages we read." ], "score": 50 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/prefactor.json", "live": { "slug": "prefactor", "probe": { "target": "https://app.prefactorai.com/api/v1", "method": "get", "lastAt": "2026-10-09T11:46:37.762898209Z", "lastOk": true, "lastStatus": 404, "lastMs": 142, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 310, "p95ms24h": 398, "samples24h": 175, "samples30d": 175, "days": [ { "date": "2026-10-08", "probes": 50, "ok": 50 }, { "date": "2026-10-09", "probes": 125, "ok": 125 } ] }, "vendorStatus": { "page": "https://status.prefactor.ai", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-10-09T07:58:26.891368591Z" }, "updatedAt": "2026-10-09T11:46:37.762898209Z" } }, "answer": "W\u0026B Weave scores 66.7 (B) on agent readiness against Prefactor's 65.6 (B), and leads in 3 of 7 scored categories. Prefactor leads on reliability, schema \u0026 documentation, agent ergonomics and payments \u0026 pricing.", "b": { "slug": "wandb-weave", "name": "W\u0026B Weave", "vendor": "Weights \u0026 Biases (CoreWeave)", "vendorUrl": "https://wandb.ai", "kind": "http-api", "category": "agent-observability", "summary": "W\u0026B Weave is CoreWeave Forge's tracing and evaluation service for LLM applications and agents. It takes traces from Python and TypeScript SDKs or an OTLP endpoint and exposes them through a REST Service API.", "url": "https://www.anchorterminal.com/tools/wandb-weave", "markdownUrl": "https://www.anchorterminal.com/tools/wandb-weave.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/wandb-weave.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/wandb-weave.json", "repo": "https://github.com/wandb/weave", "license": "Hosted service under the W\u0026B Master Service Agreement. The Weave SDKs and trace server source on GitHub are Apache-2.0, and the W\u0026B MCP server is MIT", "transports": [ "http", "streamable-http" ], "remoteUrl": "https://trace.wandb.ai", "packages": [ { "registry": "pypi", "name": "weave" }, { "registry": "npm", "name": "weave" } ], "auth": "api-key", "authNotes": "A Forge API key, created by a signed-in user at forge.coreweave.com/settings after signing up at id.coreweave.com/signup. The Service API takes it as `Authorization: Bearer`, the OTLP endpoints as a `wandb-api-key` header or HTTP Basic with user `api`. Personal keys reach every organisation the user belongs to. Service account keys are limited to one team or one organisation. Keys carry no per-permission scopes, the secret is shown once, and deleting a key revokes it at once.", "pricing": "freemium", "pricingNotes": "Free is $0 a month with 1 GB of Weave data ingestion. Pro starts at $60 a month with 1.5 GB, a 30 day trial and further ingestion at $0.10 per MB, billed in arrears. Enterprise is quoted, with further ingestion listed at $0.20 per MB and volume discounts on annual commitments. Ingested bytes are counted once when stored. The pricing page doesn't say whether Free needs a card (checked 2026-10-08).", "priceSummary": "$60 / mo", "where": "hosted", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the Weave docs, the OpenAPI document or the pricing page (checked 2026-10-08).", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": null, "npmWeekly": 623550, "pypiWeekly": 219442, "asOf": "2026-10-08" }, "docsUrl": "https://docs.coreweave.com/products/wandb/weave", "llmsTxt": "https://docs.coreweave.com/llms.txt", "openapi": "https://trace.wandb.ai/openapi.json", "capabilities": [ "obs.traces", "obs.evals", "obs.prompts", "obs.datasets" ], "tags": [ "hosted", "freemium", "open-source", "self-hosted", "mcp", "llms-txt", "openapi", "opentelemetry", "python", "typescript", "status-page", "soc2" ], "lastRelease": "2026-09-25", "graded": true, "anchor": { "graded": true, "score": 66.7, "grade": "B", "agentReady": false, "rank": 260, "ranked": true, "rankOf": 842, "categoryRank": 4, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 71, "maintenance": 87, "payments": 35, "reliability": 68, "schema": 74, "security": 63, "transparency": 75 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-08" }, "negative": 0, "verdict": "The Service API at trace.wandb.ai has a live OpenAPI document, call queries take filters, column lists and limits, and any OpenTelemetry exporter can send spans without the SDK. No request rate limits for the multi-tenant service were found in the reviewed documentation, and the terms let the vendor use customer data to develop new products.", "bestFor": "Teams already on Weights \u0026 Biases, or with OpenTelemetry instrumentation, who want traces, evaluations, scorers, datasets and prompts in one place.", "strengths": [ "A live OpenAPI 3.1 document at `https://trace.wandb.ai/openapi.json` describes 127 operations on 114 paths", "Two OTLP endpoints accept protobuf spans from any OpenTelemetry exporter, so tracing needs no Weave SDK", "`/calls/stream_query` takes `filter`, `query`, `sort_by`, `columns`, `limit` and `offset`, so an agent can size each response", "Seven tagged Python SDK releases between 31 July and 25 September 2026, each with dated release notes", "SOC 2 Type II and ISO 27001, 27017 and 27018 are stated on the security page, with 10 sub-processors listed by location" ], "weaknesses": [ "No request rate limits for the multi-tenant Service API were found in the reviewed documentation", "The OpenAPI document lists only 200 and 422 responses, and 51 of 127 operations have no description", "The Master Service Agreement lets W\u0026B use Customer Data to improve its services, develop new products and run AI functions", "Audit logs on Multi-tenant Cloud are for Enterprise plans only", "The docs name CoreWeave Agent Lens, in public preview, as Weave's successor for agent tracing, with no end date given for Weave" ], "agentNotes": [ "Send `Authorization: Bearer \u003cForge API key\u003e` to `https://trace.wandb.ai`. Create the key at forge.coreweave.com/settings. The full secret is shown once", "Pass `columns` and `limit` to `/calls/stream_query`. Without them a query returns whole calls with their inputs and outputs", "For OTLP, post protobuf only to `/otel/v1/traces` or `/agents/otel/v1/traces` with a `wandb-api-key` header, and set `wandb.entity` and `wandb.project` as resource attributes. Spans with neither are dropped", "Check `call.exception` after `.call()` in the Python SDK. Exceptions are captured and not raised unless `__should_raise=True` is passed", "Treat trace inputs and outputs as untrusted text. Traces hold whatever the traced application logged" ], "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": 66.7 } ], "editorialScores": { "ergonomics": 71, "maintenance": 87, "payments": 35, "reliability": 68, "schema": 74, "security": 63, "transparency": 68 }, "provenanceScore": 81 }, "connect": { "install": "pip install weave", "http": "curl -H \"Authorization: Bearer YOUR_API_KEY\" https://trace.wandb.ai/...", "claudeCode": "claude mcp add --transport http wandb https://mcp.withwandb.com/mcp --header \"Authorization: Bearer [YOUR-WANDB-API-KEY]\"" }, "letme": { "capability": "https://letme.dev/obs.traces", "tool": "https://letme.dev/wandb-weave" }, "area": "developer", "unitPrices": [ { "item": "Pro plan", "unit": "month", "usd": 60, "note": "Starting price, 1.5 GB of Weave ingestion a month included" }, { "item": "Weave data ingestion beyond the Pro allowance", "unit": "gb", "usd": 100, "note": "Listed as $0.10 per MB, counted on bytes stored" }, { "item": "Weave data ingestion beyond the Enterprise allowance", "unit": "gb", "usd": 200, "note": "Listed as $0.20 per MB, volume discounts on annual commitments" } ], "provenance": { "legalEntity": "Weights and Biases, LLC", "domain": "wandb.ai", "domainRegistered": "2017-12-16", "endpointOnVendorDomain": true, "terms": "https://wandb.ai/site/terms/", "privacy": "https://docs.coreweave.com/policies/terms-of-service/privacy-policy", "statusPage": "https://status.forge.coreweave.com", "changelog": "https://docs.coreweave.com/release-notes/weave-sdk-releases", "securityTxt": "none", "checked": "2026-10-08", "notes": [ "The W\u0026B Master Service Agreement, last updated 30 September 2026, names Weights and Biases, LLC, a Delaware company at 400 Alabama Street, San Francisco. The products are sold as CoreWeave Forge.", "wandb.ai/site/privacy redirects to CoreWeave's privacy policy, last updated 24 February 2026, which covers CoreWeave, Inc. and its affiliates as controller and says it doesn't apply to data processed for customers. The DPA of 22 April 2026 at wandb.ai/site/dpa covers that data.", "The Service API and OTLP endpoints run on trace.wandb.ai. The hosted MCP server runs on mcp.withwandb.com and the console on forge.coreweave.com.", "wandb.ai/.well-known/security.txt redirects to a Forge page that answers \"Invalid .well-known request\", and coreweave.com/.well-known/security.txt returns 404. The security page takes reports at security@coreweave.com.", "status.wandb.com, which the SLA cites, redirects to status.forge.coreweave.com.", "RDAP for wandb.ai gives a registration date of 2017-12-16." ], "score": 81 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/wandb-weave.json", "live": { "slug": "wandb-weave", "probe": { "target": "https://trace.wandb.ai", "method": "get", "lastAt": "2026-10-09T11:46:45.671898702Z", "lastOk": true, "lastStatus": 200, "lastMs": 156, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 144, "p95ms24h": 227, "samples24h": 44, "samples30d": 44, "days": [ { "date": "2026-10-09", "probes": 44, "ok": 44 } ] }, "vendorStatus": { "page": "https://status.forge.coreweave.com", "indicator": "none", "summary": "All Systems Operational", "checkedAt": "2026-10-09T11:41:15.82222577Z" }, "updatedAt": "2026-10-09T11:46:45.671898702Z" } }, "facts": [ { "a": "HTTP API", "b": "HTTP API", "name": "Kind" }, { "a": "Prefactor Pty Ltd", "b": "Weights \u0026 Biases (CoreWeave)", "name": "Vendor" }, { "a": "https://app.prefactorai.com/api/v1", "b": "https://trace.wandb.ai", "name": "Hosted endpoint" }, { "a": "HTTP", "b": "HTTP, Streamable HTTP", "name": "Transports" }, { "a": "API key", "b": "API key", "name": "Auth" }, { "a": "Freemium", "b": "Freemium", "name": "Pricing" }, { "a": "no", "b": "no", "name": "x402" }, { "a": "Proprietary hosted service. The TypeScript and Python SDKs and the CLI are MIT", "b": "Hosted service under the W\u0026B Master Service Agreement. The Weave SDKs and trace server source on GitHub are Apache-2.0, and the W\u0026B MCP server is MIT", "name": "Licence" }, { "a": "no", "b": "no", "name": "Read-only variant documented" }, { "a": "yes", "b": "yes", "name": "llms.txt" }, { "a": "2026-09-13", "b": "2026-09-25", "name": "Last release" }, { "a": "no document linked", "b": "2026-09-30", "name": "Terms last updated" }, { "a": "couldn't be read", "b": "2026-02-24", "name": "Privacy policy last updated" }, { "a": "", "b": "not found in the text", "name": "Customer content may train models" }, { "a": "", "b": "yes", "name": "Terms restrict automated access" }, { "a": "", "b": "yes", "name": "Terms restrict benchmarking" }, { "a": "", "b": "not found in the text", "name": "Terms or service can change without notice" }, { "a": "", "b": "yes", "name": "Arbitration or class-action waiver" }, { "a": "3 stars, 19 npm/wk, 28 PyPI/wk", "b": "624k npm/wk, 219k PyPI/wk", "name": "Popularity" } ], "faq": [ { "answer": "W\u0026B Weave scores 66.7 (B) on agent readiness against Prefactor's 65.6 (B), and leads in 3 of 7 scored categories. Prefactor leads on reliability, schema \u0026 documentation, agent ergonomics and payments \u0026 pricing.", "question": "Which is better for AI agents, Prefactor or W\u0026B Weave?" }, { "answer": "Both need an API key.", "question": "Do Prefactor and W\u0026B Weave need an API key?" }, { "answer": "Yes. Prefactor has a hosted endpoint at https://app.prefactorai.com/api/v1 and W\u0026B Weave at https://trace.wandb.ai.", "question": "Can an agent call Prefactor and W\u0026B Weave without installing anything?" }, { "answer": "No open-source release is listed for Prefactor. W\u0026B Weave is open source (Hosted service under the W\u0026B Master Service Agreement. The Weave SDKs and trace server source on GitHub are Apache-2.0, and the W\u0026B MCP server is MIT).", "question": "Are Prefactor and W\u0026B Weave open source?" } ], "goodFor": [ { "aheadOn": [ "Reliability, 78 against 68", "Schema \u0026 documentation, 80 against 74", "Agent ergonomics, 88 against 71", "Payments \u0026 pricing, 40 against 35" ], "also": [ "Free to start without a card" ], "goodFor": "A team that wants an auditable record of agent runs with declared data-risk labels, quality payloads from its own evaluations and a remote stop signal.", "slug": "prefactor", "watchFor": "The pricing page lists hold, approve or block and PII detection on every plan, while the docs say a risk threshold blocks nothing and that Prefactor does not detect sensitive data" }, { "aheadOn": [ "Security \u0026 auth, 63 against 56", "Maintenance \u0026 community, 87 against 82", "Transparency \u0026 trust, 75 against 42" ], "also": [ "Open source", "No incidents deducted, where Prefactor loses 3 points for them" ], "goodFor": "Teams already on Weights \u0026 Biases, or with OpenTelemetry instrumentation, who want traces, evaluations, scorers, datasets and prompts in one place.", "slug": "wandb-weave", "watchFor": "No request rate limits for the multi-tenant Service API were found in the reviewed documentation" } ], "job": { "capability": "obs.traces", "name": "Obs traces" }, "others": [ { "json": "https://www.anchorterminal.com/compare/arize-phoenix-vs-prefactor.json", "title": "Arize Phoenix vs Prefactor", "url": "https://www.anchorterminal.com/compare/arize-phoenix-vs-prefactor" }, { "json": "https://www.anchorterminal.com/compare/arize-phoenix-vs-wandb-weave.json", "title": "Arize Phoenix vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/arize-phoenix-vs-wandb-weave" }, { "json": "https://www.anchorterminal.com/compare/baserun-vs-prefactor.json", "title": "Baserun vs Prefactor", "url": "https://www.anchorterminal.com/compare/baserun-vs-prefactor" }, { "json": "https://www.anchorterminal.com/compare/baserun-vs-wandb-weave.json", "title": "Baserun vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/baserun-vs-wandb-weave" }, { "json": "https://www.anchorterminal.com/compare/braintrust-vs-prefactor.json", "title": "Braintrust API + MCP vs Prefactor", "url": "https://www.anchorterminal.com/compare/braintrust-vs-prefactor" }, { "json": "https://www.anchorterminal.com/compare/braintrust-vs-wandb-weave.json", "title": "Braintrust API + MCP vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/braintrust-vs-wandb-weave" }, { "json": "https://www.anchorterminal.com/compare/galileo-vs-prefactor.json", "title": "Galileo API + MCP vs Prefactor", "url": "https://www.anchorterminal.com/compare/galileo-vs-prefactor" }, { "json": "https://www.anchorterminal.com/compare/galileo-vs-wandb-weave.json", "title": "Galileo API + MCP vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/galileo-vs-wandb-weave" }, { "json": "https://www.anchorterminal.com/compare/helicone-vs-prefactor.json", "title": "Helicone AI Gateway + MCP vs Prefactor", "url": "https://www.anchorterminal.com/compare/helicone-vs-prefactor" }, { "json": "https://www.anchorterminal.com/compare/helicone-vs-wandb-weave.json", "title": "Helicone AI Gateway + MCP vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/helicone-vs-wandb-weave" }, { "json": "https://www.anchorterminal.com/compare/honeyhive-vs-prefactor.json", "title": "HoneyHive vs Prefactor", "url": "https://www.anchorterminal.com/compare/honeyhive-vs-prefactor" }, { "json": "https://www.anchorterminal.com/compare/honeyhive-vs-wandb-weave.json", "title": "HoneyHive vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/honeyhive-vs-wandb-weave" }, { "json": "https://www.anchorterminal.com/compare/laminar-vs-prefactor.json", "title": "Laminar API + MCP vs Prefactor", "url": "https://www.anchorterminal.com/compare/laminar-vs-prefactor" }, { "json": "https://www.anchorterminal.com/compare/laminar-vs-wandb-weave.json", "title": "Laminar API + MCP vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/laminar-vs-wandb-weave" }, { "json": "https://www.anchorterminal.com/compare/langfuse-vs-prefactor.json", "title": "Langfuse API + MCP vs Prefactor", "url": "https://www.anchorterminal.com/compare/langfuse-vs-prefactor" }, { "json": "https://www.anchorterminal.com/compare/langfuse-vs-wandb-weave.json", "title": "Langfuse API + MCP vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/langfuse-vs-wandb-weave" }, { "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-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-wandb-weave.json", "title": "LangWatch vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/langwatch-vs-wandb-weave" }, { "json": "https://www.anchorterminal.com/compare/prefactor-vs-respan.json", "title": "Prefactor vs Respan API + MCP", "url": "https://www.anchorterminal.com/compare/prefactor-vs-respan" }, { "json": "https://www.anchorterminal.com/compare/respan-vs-wandb-weave.json", "title": "Respan API + MCP vs W\u0026B Weave", "url": "https://www.anchorterminal.com/compare/respan-vs-wandb-weave" } ], "scores": [ { "by": 10, "edge": "prefactor", "key": "reliability", "name": "Reliability", "prefactor": 78, "wandb-weave": 68, "weight": 16 }, { "key": "performance", "name": "Performance", "pending": true, "weight": 10 }, { "by": 6, "edge": "prefactor", "key": "schema", "name": "Schema \u0026 documentation", "prefactor": 80, "wandb-weave": 74, "weight": 13 }, { "by": 17, "edge": "prefactor", "key": "ergonomics", "name": "Agent ergonomics", "prefactor": 88, "wandb-weave": 71, "weight": 13 }, { "by": 7, "edge": "wandb-weave", "key": "security", "name": "Security \u0026 auth", "prefactor": 56, "wandb-weave": 63, "weight": 14 }, { "by": 5, "edge": "prefactor", "key": "payments", "name": "Payments \u0026 pricing", "prefactor": 40, "wandb-weave": 35, "weight": 10 }, { "key": "tasks", "name": "Task success", "pending": true, "weight": 10 }, { "by": 5, "edge": "wandb-weave", "key": "maintenance", "name": "Maintenance \u0026 community", "prefactor": 82, "wandb-weave": 87, "weight": 7 }, { "by": 33, "edge": "wandb-weave", "key": "transparency", "name": "Transparency \u0026 trust", "prefactor": 42, "wandb-weave": 75, "weight": 7 } ], "summary": "W\u0026B Weave scores 66.7 (B) on agent readiness against Prefactor's 65.6 (B), and leads in 3 of 7 scored categories. Prefactor leads on reliability, schema \u0026 documentation, agent ergonomics and payments \u0026 pricing. Both do obs traces.", "verdicts": { "prefactor": "The public OpenAPI document lists 157 operations, each accepting an idempotency key, and tokens can be read-only or bound to one agent deployment. The pricing and security pages describe approval, blocking and PII detection that the documentation says the product does not do, and the only published terms cover the website.", "wandb-weave": "The Service API at trace.wandb.ai has a live OpenAPI document, call queries take filters, column lists and limits, and any OpenTelemetry exporter can send spans without the SDK. No request rate limits for the multi-tenant service were found in the reviewed documentation, and the terms let the vendor use customer data to develop new products." } }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/prefactor-vs-wandb-weave", "json": "https://www.anchorterminal.com/compare/prefactor-vs-wandb-weave.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/prefactor-vs-wandb-weave.md", "slim": "https://www.anchorterminal.com/compare/prefactor-vs-wandb-weave.min.md" }, "markdown": "W\u0026B Weave scores 66.7 (B) on agent readiness against Prefactor's 65.6 (B), and leads in 3 of 7 scored categories. Prefactor leads on reliability, schema \u0026 documentation, agent ergonomics and payments \u0026 pricing. Both do obs traces.\n\n- Prefactor: grade B, 65.6/100, rank #286 of 842. Markdown https://www.anchorterminal.com/tools/prefactor.md · JSON https://www.anchorterminal.com/api/v1/tools/prefactor.json\n- W\u0026B Weave: grade B, 66.7/100, rank #260 of 842. Markdown https://www.anchorterminal.com/tools/wandb-weave.md · JSON https://www.anchorterminal.com/api/v1/tools/wandb-weave.json\n\n## Which one, for what\n\n### Prefactor (B)\n\nGood for: A team that wants an auditable record of agent runs with declared data-risk labels, quality payloads from its own evaluations and a remote stop signal.\n\nAhead on:\n- Reliability, 78 against 68\n- Schema \u0026 documentation, 80 against 74\n- Agent ergonomics, 88 against 71\n- Payments \u0026 pricing, 40 against 35\n\nAlso in its favour:\n- Free to start without a card\n\nWatch for: The pricing page lists hold, approve or block and PII detection on every plan, while the docs say a risk threshold blocks nothing and that Prefactor does not detect sensitive data\n\n### W\u0026B Weave (B)\n\nGood for: Teams already on Weights \u0026 Biases, or with OpenTelemetry instrumentation, who want traces, evaluations, scorers, datasets and prompts in one place.\n\nAhead on:\n- Security \u0026 auth, 63 against 56\n- Maintenance \u0026 community, 87 against 82\n- Transparency \u0026 trust, 75 against 42\n\nAlso in its favour:\n- Open source\n- No incidents deducted, where Prefactor loses 3 points for them\n\nWatch for: No request rate limits for the multi-tenant Service API were found in the reviewed documentation\n\n\n## Score by category\n\n| Category | Weight | Prefactor | W\u0026B Weave | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 78 | 68 | Prefactor +10 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 80 | 74 | Prefactor +6 |\n| Agent ergonomics | 13% (16.2 this run) | 88 | 71 | Prefactor +17 |\n| Security \u0026 auth | 14% (17.5 this run) | 56 | 63 | W\u0026B Weave +7 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 40 | 35 | Prefactor +5 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 82 | 87 | W\u0026B Weave +5 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 42 | 75 | W\u0026B Weave +33 |\n| Negative events | ≤15 | -3 | 0 | |\n| **Total** | | **65.6 · B** | **66.7 · B** | |\n\n## Facts side by side\n\n| Fact | Prefactor | W\u0026B Weave |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | Prefactor Pty Ltd | Weights \u0026 Biases (CoreWeave) |\n| Hosted endpoint | `https://app.prefactorai.com/api/v1` | `https://trace.wandb.ai` |\n| Transports | HTTP | HTTP, Streamable HTTP |\n| Auth | API key | API key |\n| Pricing | Freemium | Freemium |\n| x402 | no | no |\n| Licence | Proprietary hosted service. The TypeScript and Python SDKs and the CLI are MIT | Hosted service under the W\u0026B Master Service Agreement. The Weave SDKs and trace server source on GitHub are Apache-2.0, and the W\u0026B MCP server is MIT |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| Last release | 2026-09-13 | 2026-09-25 |\n| Terms last updated | no document linked | 2026-09-30 |\n| Privacy policy last updated | couldn't be read | 2026-02-24 |\n| Customer content may train models | | not found in the text |\n| Terms restrict automated access | | yes |\n| Terms restrict benchmarking | | yes |\n| Terms or service can change without notice | | not found in the text |\n| Arbitration or class-action waiver | | yes |\n| Popularity | 3 stars, 19 npm/wk, 28 PyPI/wk | 624k npm/wk, 219k PyPI/wk |\n\n## Verdicts\n\n**Prefactor.** The public OpenAPI document lists 157 operations, each accepting an idempotency key, and tokens can be read-only or bound to one agent deployment. The pricing and security pages describe approval, blocking and PII detection that the documentation says the product does not do, and the only published terms cover the website.\n\n**W\u0026B Weave.** The Service API at trace.wandb.ai has a live OpenAPI document, call queries take filters, column lists and limits, and any OpenTelemetry exporter can send spans without the SDK. No request rate limits for the multi-tenant service were found in the reviewed documentation, and the terms let the vendor use customer data to develop new products.\n\n## Before you call either\n\n### Prefactor\n\n1. Send requests to `https://app.prefactorai.com/api/v1` with `Authorization: Bearer \u003ctoken\u003e`. The API host is not on the `prefactor.tech` or `prefactor.ai` domains\n2. Ask for a deployment-scoped token, or an account token created with `role` set to `read_only`, since the default role is `full_access` with a two-year expiry\n3. Pass `redacted: true` on span list and detail queries, because the API returns marked sensitive values unless asked otherwise\n4. On 429 wait for `retry_after_ms`. Limits use one-minute windows and the SDKs' default retries ignore the server's hint\n5. Treat terminate as a request. Check the control signal on span responses or poll the instance, because Prefactor does not stop the process\n\n### W\u0026B Weave\n\n1. Send `Authorization: Bearer \u003cForge API key\u003e` to `https://trace.wandb.ai`. Create the key at forge.coreweave.com/settings. The full secret is shown once\n2. Pass `columns` and `limit` to `/calls/stream_query`. Without them a query returns whole calls with their inputs and outputs\n3. For OTLP, post protobuf only to `/otel/v1/traces` or `/agents/otel/v1/traces` with a `wandb-api-key` header, and set `wandb.entity` and `wandb.project` as resource attributes. Spans with neither are dropped\n4. Check `call.exception` after `.call()` in the Python SDK. Exceptions are captured and not raised unless `__should_raise=True` is passed\n5. Treat trace inputs and outputs as untrusted text. Traces hold whatever the traced application logged\n\n## Questions\n\n### Which is better for AI agents, Prefactor or W\u0026B Weave?\n\nW\u0026B Weave scores 66.7 (B) on agent readiness against Prefactor's 65.6 (B), and leads in 3 of 7 scored categories. Prefactor leads on reliability, schema \u0026 documentation, agent ergonomics and payments \u0026 pricing.\n\n### Do Prefactor and W\u0026B Weave need an API key?\n\nBoth need an API key.\n\n### Can an agent call Prefactor and W\u0026B Weave without installing anything?\n\nYes. Prefactor has a hosted endpoint at https://app.prefactorai.com/api/v1 and W\u0026B Weave at https://trace.wandb.ai.\n\n### Are Prefactor and W\u0026B Weave open source?\n\nNo open-source release is listed for Prefactor. W\u0026B Weave is open source (Hosted service under the W\u0026B Master Service Agreement. The Weave SDKs and trace server source on GitHub are Apache-2.0, and the W\u0026B MCP server is MIT).\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/prefactor-vs-wandb-weave.json, and with the fewest tokens: https://www.anchorterminal.com/compare/prefactor-vs-wandb-weave.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"prefactor\", \"b\": \"wandb-weave\"}`. From a terminal: `anchor compare prefactor wandb-weave`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/prefactor.json and https://www.anchorterminal.com/api/v1/tools/wandb-weave.json\n\n## Other comparisons with Prefactor or W\u0026B Weave\n\n- [Arize Phoenix vs Prefactor](https://www.anchorterminal.com/compare/arize-phoenix-vs-prefactor.md)\n- [Arize Phoenix vs W\u0026B Weave](https://www.anchorterminal.com/compare/arize-phoenix-vs-wandb-weave.md)\n- [Baserun vs Prefactor](https://www.anchorterminal.com/compare/baserun-vs-prefactor.md)\n- [Baserun vs W\u0026B Weave](https://www.anchorterminal.com/compare/baserun-vs-wandb-weave.md)\n- [Braintrust API + MCP vs Prefactor](https://www.anchorterminal.com/compare/braintrust-vs-prefactor.md)\n- [Braintrust API + MCP vs W\u0026B Weave](https://www.anchorterminal.com/compare/braintrust-vs-wandb-weave.md)\n- [Galileo API + MCP vs Prefactor](https://www.anchorterminal.com/compare/galileo-vs-prefactor.md)\n- [Galileo API + MCP vs W\u0026B Weave](https://www.anchorterminal.com/compare/galileo-vs-wandb-weave.md)\n- [Helicone AI Gateway + MCP vs Prefactor](https://www.anchorterminal.com/compare/helicone-vs-prefactor.md)\n- [Helicone AI Gateway + MCP vs W\u0026B Weave](https://www.anchorterminal.com/compare/helicone-vs-wandb-weave.md)\n- [HoneyHive vs Prefactor](https://www.anchorterminal.com/compare/honeyhive-vs-prefactor.md)\n- [HoneyHive vs W\u0026B Weave](https://www.anchorterminal.com/compare/honeyhive-vs-wandb-weave.md)\n- [Laminar API + MCP vs Prefactor](https://www.anchorterminal.com/compare/laminar-vs-prefactor.md)\n- [Laminar API + MCP vs W\u0026B Weave](https://www.anchorterminal.com/compare/laminar-vs-wandb-weave.md)\n- [Langfuse API + MCP vs Prefactor](https://www.anchorterminal.com/compare/langfuse-vs-prefactor.md)\n- [Langfuse API + MCP vs W\u0026B Weave](https://www.anchorterminal.com/compare/langfuse-vs-wandb-weave.md)\n- [LangSmith API + MCP vs Prefactor](https://www.anchorterminal.com/compare/langsmith-vs-prefactor.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 W\u0026B Weave](https://www.anchorterminal.com/compare/langwatch-vs-wandb-weave.md)\n- [Prefactor vs Respan API + MCP](https://www.anchorterminal.com/compare/prefactor-vs-respan.md)\n- [Respan API + MCP vs W\u0026B Weave](https://www.anchorterminal.com/compare/respan-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": "Prefactor vs W\u0026B Weave", "url": "" } ], "description": "W\u0026B Weave scores 66.7 (B) on agent readiness against Prefactor's 65.6 (B), and leads in 3 of 7 scored categories. Prefactor leads on reliability, schema \u0026 documentation, agent ergonomics and payments \u0026 pricing. Both do obs traces. Category scores, facts, verdicts and agent notes…", "facts": [ "Prefactor B 65.6", "W\u0026B Weave B 66.7", "scores" ], "h1": "Prefactor vs W\u0026B Weave", "image": "https://www.anchorterminal.com/assets/og/compare-prefactor-vs-wandb-weave.png", "path": "/compare/prefactor-vs-wandb-weave", "published": "2026-10-01", "section": "tools", "title": "Prefactor vs W\u0026B Weave for AI agents, B 65.6 vs B 66.7", "toc": null, "updated": "2026-10-09", "url": "https://www.anchorterminal.com/compare/prefactor-vs-wandb-weave" }, "tokens": { "markdown": 2550, "slim": 730 }, "version": 1 }