LangWatch

What LangWatch is

LangWatch is a testing and observability platform for agent and language model applications. Its distinguishing tool is simulated user testing: it runs conversations against your agent to surface failures and regressions before real users meet them, alongside monitoring and debugging once deployed.

What you can do with it

• Simulate users to find failure cases
• Detect regressions between versions
• Monitor behaviour in production
• Debug with traces
• Track experience fluctuations over time

Who it is for

• AI engineering and product teams
• Platform teams maintaining agents
• Organisations needing continuous verification

What to watch out for

• Simulated users only cover what you script; novel real-world behaviour still escapes
• Evaluation needs an agreed set of high-frequency tasks and scoring rules to mean anything
• Traces capture user inputs, so redact personal data and set retention
• Monitoring without owners and thresholds becomes unused dashboard real estate