Danube

All your tools. None of your passwords. Danube is a marketplace for AI agent tools. One API key unlocks 100+ integrations including Slack, GitHub, Gmail, and Stripe, with no per-service OAuth. Publishers register an OpenAPI or MCP spec, set per-execution pricing, and get paid every time an agent calls their tool. Security-first: agents never see your credentials. You approve access via device flow and revoke anytime. B2A: Business-to-Agent. The new distribution channel.