Respan
Nested traces for every LLM call, tool run, and agent turn
37 Best Weights & Biases Alternatives & Competitors (2026)
The top alternatives to Weights & Biases in the Observability, Prompts & Evals space, compared on features, pricing, and what they're best at.
Updated March 9, 2026
Why look beyond Weights & Biases?
Weights and Biases (W and B) is a machine learning operations platform founded in 2017 by Chris Van Pelt, Lukas Biewald, and Shawn Lewis in San Francisco, California. The platform offers performance visualization tools for machine learning, helping companies track models, visualize performance, and automate training and model improvement workflows. W and B provides comprehensive experiment tracking, model versioning, and collaborative tools for ML teams. In March 2025, Weights and Biases was acquired by CoreWeave, strengthening its position in the AI infrastructure ecosystem. The company raised a total of USD 250M from investors including CoreWeave, Coatue, Bloomberg Beta, and Insight Partners. W and B offers a free tier for personal projects and provides academic institutions with free Pro licenses for non-profit research, including unlimited tracked hours, 200GB cloud storage, up to 25GB/month of Weave data ingestion, and up to 100 seats. Paid plans start at USD 60/month with additional cloud storage available at USD 0.03 per GB.
Common reasons users explore alternatives
- Pricing can become expensive for large teams and enterprises
- Additional storage costs can add up quickly for data-intensive workflows
- Learning curve for advanced features may slow initial adoption
- Platform complexity may be overkill for simple ML projects
Top alternatives to Weights & Biases
LangSmith
Native tracing for LangChain and LangGraph
MLflow
OpenTelemetry-based tracing for LLMs and agents
Langfuse
Tracing for LLM calls, tool runs, and agent steps
Arize AI
ML observability with LLM support
Helicone
Datadog LLM
LLM monitoring within Datadog platform
Traceloop
OpenTelemetry
HoneyHive
Prompt management
Braintrust
Experiments comparing prompts and models
Promptfoo
Phoenix
OpenTelemetry-based LLM and agent tracing
Patronus AI
Automated LLM evaluation platform
Humanloop
Portkey
Sentry
DeepEval
Ragas
RAG-specific evaluation framework
LangWatch
Multi-turn agent simulation testing
Galileo AI
LLM output quality evaluation
PromptLayer
Maxim AI
Distributed tracing for LLM and agent apps
Confident AI
DeepEval open-source evaluation framework
Opik
Agenta
Future AGI
Multimodal evaluation (text, image, audio, video)
Lunary
Parea AI
Chamber
ML infrastructure automation
Moda
Hallucination detection
Ashr
Multi-modal synthetic testing
Sentrial
Agent failure root cause analysis
Athina AI
Laminar
Agent tracing with a readable transcript view
OpenObserve
Logs, metrics, traces, RUM, and session replay
AgentOps
Session replay with time-travel debugging
Fiddler AI
Agentic observability across multi-step agent workflows
Run Observability, Prompts & Evals in production with Respan
One platform for routing, observability, tracing, and evals across every LLM provider.
Compare Weights & Biases alternatives with Respan
10KFree traces/mo
1,000+Models
5 minSetup
Respan lets you trace LLM and agent calls across any model or framework, A/B test prompts on production traffic, and route requests across 1,000+ models through one gateway.
Try Respan free