LangWatch

The product is a simulation-based testing and evaluation platform for AI agents that catches failures before production by running realistic text and voice user scenarios, scoring response quality, tracing agent steps, and monitoring cost and latency. It is for developers and data teams in B2B organizations building and operating AI agents and assistants. It is delivered as a SaaS platform with self-host deployment in 15 minutes and open-source frameworks, working with every agent framework via API or internal hooks without rewrites.

Key features

• Agentic AI testing with simulations
• Realistic text and voice user simulations
• LLM evaluation and scoring
• LLM as a judge with reasoning
• Trace every agent step
• Monitor cost and latency
• Online production evaluations
• Pairwise output comparison
• Multimodal image and media evaluation
• Prompt versioning and A/B testing
• GitHub sync for prompts
• Voice AI agent testing at scale
• LLM red-teaming for safety gaps
• Virtual keys with budgets and routing
• Full audit trail and audit logs
• Custom graph alerts via Slack
• Scenario creation in plain language
• Local and CI scenario execution
• Tool, skill and MCP tracing
• Mockable tools for deterministic runs