Harmonica is an open source project aimed at making group sensemaking faster, easier and more engaging. We accomplish this by using GPT-powered chatbot that facilitates sessions in popular messengers (Discord, Slack, Telegram, Whatsapp). With the right prompting techniques and vector databases, LLMs can synthesize thousands of responses in real time, talk to each participant 1:1 and ask questions to identify common themes or cross-pollinate ideas. Hosts can select from a library of facilitation templates to hire Harmonica in various use cases: writing proposals, finding a shared purpose, formulating OKRs, deliberating on grants / funds allocation, running retrospectives, developing roadmaps, you name it. Harmonica is a new element of online collaboration stack, and a future-proof foundation for your collective intelligence.