Composio bets every AI agent needs a tool layer; $25M Series A, 49.5K-star repo

Open-source platform that gives AI agents 1,000+ pre-authenticated toolkits, per-user sessions, authentication and sandboxes so agents can act on apps instead of just answering.

That every AI agent needs a shared skill layer of pre-authenticated tools, and an open-source SDK can become the default way agents connect to thousands of apps.

$25M Series A led by Lightspeed Venture Partners (July 2025), with SV Angel and HubSpot founder Dharmesh Shah, bringing total funding to roughly $29M.

Founded 2023 in San Francisco by Soham Ganatra and Karan Vaidya, Composio started as the open-source glue between AI agents and the apps they needed to act on. The founding insight: an agent is only as useful as the tools it can call, and authentication is the part nobody wants to build.

By July 2025 the platform counted 200+ companies, including Glean, and announced a $25M Series A led by Lightspeed. Composio says agents can connect to more than 3,000 cloud apps and software tools, supports MCP, and ships a reinforcement-learning layer it claims lets agents improve and share what they learn.

Still scaling: as of September 2026 the SDK remains open-source and MIT-licensed, its awesome-claude-skills list grew 32.7x to 49.5K stars in Q1 2026, and adapters now cover OpenAI Agents, Claude, LangChain, CrewAI, Vercel AI SDK and more.

Agents are only as valuable as the tools they can call, and auth is the part every team wants to outsource — Composio made that its wedge.

MIT-licensed SDK plus viral curated lists put Composio inside developer workflows before it had a sales team, the same playbook as other open-source infrastructure winners.

Riding the MCP standard let Composio plug into Claude, Cursor, OpenAI Agents and every emerging harness without being locked to one model vendor.

The agents-learn-from-each-other narrative gave investors a scaling story beyond API reselling, supporting a $29M total raise.

Open-source distribution can win infrastructure layers: a free SDK and curated list put Composio inside developers' workflows before any sales team, so the paid platform rides on free adoption.

As of September 2026 Composio is live and scaling: the MIT-licensed SDK remains on GitHub with 1,000+ toolkits, adapters for the major agent frameworks, and a hosted platform sold to enterprise customers. Its awesome-claude-skills list is one of the fastest-growing agent-curated repos on GitHub (49.5K stars by end of Q1 2026), and the company continues to position itself as the skill layer for AI agents — infrastructure for authentication, tool execution and cross-agent learning — rather than as a model or an app.