Open source function-calling projects
Every project in the registry tagged function-calling, ranked by real GitHub adoption.
Composio powers 1000+ toolkits, tool search, context management, authentication, and a sandboxed workbench to help you build AI agents that turn intent into act
All-in-one LLM CLI tool featuring Shell Assistant, Chat-REPL, RAG, AI Tools & Agents, with access to OpenAI, Claude, Gemini, Ollama, Groq, and more.
Build reliable AI agents with unified tool integration
Harness LLMs with Multi-Agent Programming
🤖 Type-safe, provider-agnostic TypeScript AI SDK for streaming chat, tool calling, agents, and multimodal apps across OpenAI, Anthropic, Gemini, React, Vue, Sv
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Frequently asked questions
How many open source function-calling projects are there?
This registry tracks 5 projects tagged function-calling, with 53,779 GitHub stars between them. The most-adopted is composio at 30,872 stars.
Are these function-calling projects free to use?
Yes — 5 of the 5 carry an explicit open-source licence across 2 distinct licences, so there is no licence fee. Where a project also sells a hosted or enterprise version, the self-hosted path remains free.
Which function-calling project should I choose?
The list above is ranked by GitHub stars, but stars measure attention rather than fit. Check three things on each card: the licence (permissive versus copyleft), the language it is written in, and the last-push date — a high-star project that has not been pushed in a year is a liability.
Are these function-calling projects still maintained?
4 of the 5 were pushed in the last 90 days, and every card shows its exact last-push date so you can see the rest. Sort your shortlist by that date before committing to a migration.