Yes, both Vext and LangSmith offer a Free Trial.
Pricing for Vext Starts at $20/month whereas for LangSmith Starts at $0.5/month.
LangSmith offers several advantages, including Observability for LLM apps, Testing for LLM apps, Open-source SDK, Flexible integration, Adaptable to different implementations and many more functionalities.
The cons of LangSmith may include a Limited to LLM applications, Restricted early access, Beta version risks, Relies on flexible adaptation. and No mention of cross-platform compatibility