OpaquePrompts is a privacy-enhancing tool designed to address the growing concerns about data privacy in applications using large language models (LLMs) by providing a layer of protection that conceals sensitive information from LLM providers. By integrating with LangChain, OpaquePrompts allows developers to automatically identify and sanitize sensitive data in prompts before they reach LLM providers such as OpenAI, ensuring that personal information is not visible or stored by third-party services. The tool processes prompts by replacing sensitive tokens with placeholders, encrypting them, and then decrypting the information in the response, allowing the final output to appear unchanged to the user. This solution is especially valuable for industries like law, advertising, and finance, where privacy and data control are critical, enabling developers to leverage LLM capabilities without compromising data security. By incorporating OpaquePrompts into a LangChain-based application, developers can ensure user data privacy with minimal code modification, leveraging confidential computing to prevent even OpaquePrompts from accessing the underlying data.