AstrBot is an open source, cross-platform Agentic AI assistant and chatbot platform built for chats, automation, and smart collaboration. It runs directly in messaging apps and provides an agent runtime with Sub-Agents, complex workflows, tool calls, context management, scheduled tasks, runtime controls, and isolated agent sandboxes for real actions. Native MCP and Skills support expands AI capabilities, while a plugin-driven architecture provides access to more than 1,000 community extensions for productivity, group operations, content workflows, and external integrations. AstrBot supports OpenAI, Google, Anthropic, and OpenAI-compatible providers with flexible model switching, as well as text generation, vision, speech-to-text, text-to-speech, and embeddings. Its built-in knowledge base supports PDF, DOCX, and Markdown parsing, hybrid dense and BM25 retrieval, and references to multiple knowledge bases in a single conversation.