Machine Learning · head to head
Langwatch vs Weights & Biases
Langwatch
Machine Learning
LLM engineering platform for testing and evaluating AI agents in production
- From
- Free
- Rated
- -
Weights & Biases
Machine Learning
Developer tools for machine learning
- From
- Free
- Rated
- -
The short version
- Each has a real cost: Langwatch free plan limited to 50k events per month, restricting larger deployments; Weights & Biases pricing can be prohibitive for large teams without enterprise discounts
- They diverge on capability: Langwatch covers Agent simulation testing, Weights & Biases covers Experiment tracking.
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which Langwatch and Weights & Biases actually diverge.
| Attribute | Langwatch | Weights & Biases |
|---|---|---|
| Pricing model | Tiered subscription with usage-based overage charges | Unknown |
| Platforms | Web, Docker, Kubernetes | Web, Python SDK, REST API |
| Founded | Unknown | 2017 |
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Machine Learning).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in Langwatch
- Agent simulation testing
- LLM evaluation
- OpenTelemetry tracing
- Langy AI Engineer
- Governance controls
- Multiple deployment options
- Framework support
Only in Weights & Biases
- Experiment tracking
- Dataset versioning
- Model registry
- Hyperparameter sweeps
- Collaborative dashboards
- PyTorch
- TensorFlow
- Keras
What people use each for
The jobs each tool is most often brought in to do.
Langwatch
- Continuous testing of AI agents before production deploymentnot Weights & Biases
- Automated test creation from product requirementsnot Weights & Biases
- LLM response quality evaluation and scoringnot Weights & Biases
- Production agent monitoring and cost trackingnot Weights & Biases
- Governance and access control for AI systemsnot Weights & Biases
Weights & Biases
- Machine learningnot Langwatch
- Data analysisnot Langwatch
- Model trainingnot Langwatch
- Predictive analyticsnot Langwatch
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Langwatch
- Free plan limited to 50k events per month, restricting larger deployments
- Pricing in EUR may complicate budgeting for US-based teams
- Usage-based overage model can create unpredictable costs
- Self-hosted option requires DevOps expertise
Weights & Biases
- Pricing can be prohibitive for large teams without enterprise discounts
- Limited integrations compared to some competitors
- Dashboard customization options limited on lower plans
- Requires some setup and configuration knowledge
Pricing, plan by plan
Langwatch
Free- DeveloperFree
- 50k events per month
- 14-day data access
- 2 users
- Growth$29/month
- 200k events per month included
- 5 EUR per 100k additional events
- 30-day data retention
- Enterprise$undefined/custom
- Custom event limits
- Hybrid, self-hosted or on-premises deployment
- Custom SSO and RBAC
Weights & Biases
Free- FreeFree
- 5 model seats
- 5 GB storage
- 1 GB/month Weave ingestion
- Pro$60/month
- 10 seats
- 100 GB storage
- Private projects
- Teams$179/month
- Team collaboration
- Advanced analytics
- Dedicated support
Which should you pick?
Choose Langwatch if
- You need agent simulation testing.
- You want to start without paying.
- You work on Web, Docker, Kubernetes.
- You also want llm evaluation.
Choose Weights & Biases if
- You need experiment tracking.
- You want to start without paying.
- You work on Web, Python SDK, REST API.
- You also want dataset versioning.
Questions people ask
- Is Langwatch or Weights & Biases better?
- Neither clearly leads. Langwatch starts at Free and Weights & Biases at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Langwatch or Weights & Biases?
- Langwatch starts at Free and Weights & Biases at Free.
- Does Langwatch or Weights & Biases run on more platforms?
- Langwatch runs on Web, Docker, Kubernetes. Weights & Biases runs on Web, Python SDK, REST API.
- Can I use Langwatch for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is Langwatch best used for?
- Langwatch is most often used for continuous testing of ai agents before production deployment, automated test creation from product requirements, llm response quality evaluation and scoring, production agent monitoring and cost tracking. Of those, continuous testing of ai agents before production deployment and automated test creation from product requirements are not what Weights & Biases is typically brought in for.
- What can Langwatch do that Weights & Biases cannot?
- Langwatch covers Agent simulation testing, LLM evaluation, OpenTelemetry tracing, Langy AI Engineer. Weights & Biases covers Experiment tracking, Dataset versioning, Model registry, Hyperparameter sweeps.
Answered from the vendors’ own pages
Langwatch: Is there a permanent free tier?
Yes, Langwatch's Developer plan is free forever with 50k events per month, 14-day data access, 2 users, and no credit card required. It is specifically designed for individual developers prototyping AI applications.
SourceWeights & Biases: Does Weights & Biases have a free plan?
Yes. The Free tier includes 5 model seats, 5 GB storage, and 1 GB/month Weave ingestion. Academic users get unlimited tracked hours, 200 GB storage, and 100 seats at no cost.
SourceLangwatch: What is Langy and how does it save time?
Langy is an AI-powered tool that automates test creation. It converts product requirements into test scenarios, runs simulations, scores results, and generates pull requests with fixes in a median of 14 minutes.
SourceWeights & Biases: What are the paid plans for Weights & Biases?
Pro starts at $60/month with 10 seats and 100 GB storage. Team plans start at $179/month. Enterprise pricing is custom.
SourceLangwatch: What frameworks does Langwatch support?
Langwatch works with LangGraph, LangChain, CrewAI, OpenAI Agents, AWS Bedrock, Azure OpenAI, Vertex AI, and other major LLM frameworks and platforms.
SourceWeights & Biases: What machine learning features does W&B provide?
Weights & Biases captures hyperparameters, metrics, and model outputs automatically. Features include experiment tracking, interactive Reports for sharing findings, Artifacts for managing datasets and models, advanced hyperparameter sweeps, and model deployment tools.
SourceRelated pages
More on Weights & Biases
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