LangWatch vs W&B Weave
LangWatch
langwatch.ai
W&B Weave
site.wandb.aiSide by side
| Figure | LangWatch | W&B Weave |
|---|---|---|
| Price from | €29/mo | $60/mo |
| Free plan | Yes | Yes |
| Free trial | Yes | Yes |
| Open source | Yes | Yes |
| Web | Yes | Yes |
| Windows | — | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| iOS | — | Yes |
| API | Yes | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 3 | 4 |
| Spec score · AI Agent Observability Tools | 9.1 (#5) | 8.6 (#8) |
| Spec score · AI LLM Observability Tools | 9.1 (#4) | 8.6 (#7) |
| Spec score · AI Agent Evaluation Tools | 9.0 (#5) | 8.6 (#9) |
| Spec score · Model Monitoring Software | 9.0 (#5) | 8.6 (#10) |
| Spec score · LLM Observability Tools | 9.0 (#6) | 8.6 (#9) |
| Spec score · Llm Monitoring | 8.9 (#7) | 8.6 (#9) |
| Company | The site's footer identifies the maker as LangWatch B.V. and says it is built in Amsterdam. | Weights & Biases says it was founded in 2017 by Lukas Biewald, Chris Van Pelt, and Shawn Lewis and was acquired by CoreWeave in May 2025. |
| Evaluations | The platform supports offline and online evaluations, CI/CD gates, multimodal scoring, built-in evaluators and custom workflows. | An imperative evaluation API compares application or model changes with visualizations intended to expose regressions. |
| Headquarters | Amsterdam | San Francisco, California, United States |
| Integrations | Official integrations cover OpenAI, Anthropic, Google Gemini, Bedrock, Azure OpenAI, Vertex AI, Groq, Ollama and LiteLLM. | The deployment guide lists integrations for OpenAI, Anthropic, Cohere, Mistral, LangChain, LlamaIndex, DSPy, Google Gemini, Amazon Bedrock, Together and Groq. |
| Licence | The core platform is Apache 2.0; enterprise modules require a commercial production licence and the SDKs are MIT licensed. | The public Weave repository is released under the Apache-2.0 license. |
| Rating on G2 | 0.0 out of 5 from 0 reviews | 4.5 out of 5 from 83 reviews |
| SDKs and API | LangWatch publishes Python and TypeScript SDKs, OpenTelemetry ingestion and a direct REST API for sending spans. | Weave provides Python and TypeScript libraries and supports sending OpenTelemetry traces to its OTLP endpoint. |
| Security | The trust center states AES-256 encryption at rest, TLS 1.2+ in transit, AWS KMS, RBAC, MFA, SSO, encrypted backups and GDPR controls. | W&B describes AWS, Azure and Google Cloud hosting and says Trust Center certifications and security artifacts are available to approved customers. |
| Support | Developer users receive GitHub and Discord community support, while Growth includes private Slack or Teams support. | The Pro plan includes priority email and chat support, while Enterprise includes an enterprise support package. |
| System requirements | The self-host command requires Node.js 24 or newer on macOS or glibc-based Linux. | The public Weave repository requires Python 3.10 or newer, a W&B account and a W&B API key. |
| What it does | LangWatch is an AI-agent engineering platform for testing, evaluating, observing, governing and improving agents across development and production. | W&B Weave provides observability, evaluation and continuous-improvement tooling for production AI agents and LLM applications. |
Plans
In their own words
LangWatch
LangWatch is an AI agent engineering platform for teams preparing agents for production. Simulations cover multi-turn conversations, tool use, recovery, and business outcomes before launch. Evaluations can run on datasets, production traffic, or in CI/CD workflows that gate merges. Traces show agent steps alongside cost, tokens, duration, errors, evaluations, and annotations. Integrations include Python and TypeScript SDKs, OpenTelemetry, REST ingestion, model providers, and frameworks such as LangGraph, LangChain, CrewAI, and DSPy. Voice-agent testing supports OpenAI Realtime, Gemini, ElevenLabs, Google Live API, Pipecat, WebSocket bots, and Twilio. Deployment options are managed cloud, self-hosted, and hybrid; self-hosting uses Docker Compose and the customer’s ClickHouse. LangWatch is open source under Apache 2.0. The Developer plan costs nothing and includes 50k events per month, 14-day data access, and two users. Growth costs €29 a month per core seat and includes 200k events. The trust center lists encryption, access controls, privacy features, and enterprise DPAs.
W&B Weave
W&B Weave provides observability and continuous-improvement tools for production AI agents. It structures traces as sessions and turns, with steps, tools, and sub-agents represented individually. Built-in and custom signals classify interactions, and alerts can be sent through Slack notifications or webhook automations. Its evaluation tools compare results and visualize regressions before deployment; the Playground lets teams compare models and prompting methods against production traces. Safety scorers cover toxicity, bias, personal information, and hallucinations, while quality scorers assess coherence, fluency, and context relevance. Weave works with LangChain and LlamaIndex and supports models from OpenAI, Meta, Amazon Bedrock, and Anthropic. Python and TypeScript libraries are available, as is OpenTelemetry trace submission through an OTLP endpoint. Weave runs on API, Linux, macOS, self-hosted, web, and Windows platforms. The Free plan costs nothing and includes 1 GB of monthly ingestion and 5 GB of storage. Pro costs $60 a month, with 1.5 GB of monthly ingestion; extra ingestion costs $0.10 per MB. A 30-day trial is listed.