In 2023, the surge in interest in Generative AI, sparked by ChatGPT, led companies to explore strategies for incorporating this technology into their products. LangSmith, a cloud platform from LangChain, has been instrumental in helping teams transition from prototype to production by providing features like tracing, regression testing, and evaluation. The platform's usage data reveals insights into the construction and testing of LLM applications, with retrieval emerging as a key method for combining data and 42% of complex queries involving retrieval. The introduction of LangChain Expression Language (LCEL) has facilitated the creation of complex, customized chains, reflecting a trend towards experimentation and customization in the GenAI landscape. OpenAI is the leading LLM provider, with AzureOpenAI and other proprietary and open-source models also gaining traction. Vectorstores play a crucial role in LLM applications, with local vectorstores being most popular, and Pinecone and Weaviate leading among hosted options. Testing and evaluation are major challenges, with LangSmith enabling users to formulate various metrics, predominantly using LLMs for output evaluation, although custom evaluators are common due to the specificity required by different applications. As the year concludes, LangSmith is establishing itself as a key tool for teams aiming to move from prototype to production in the evolving field of LLM app development.