a16z Leads $20M Seed for Runta, a Startup Building an Execution Layer to Keep AI Agents in Check

Runta, a startup building sandboxes and guardrails designed to keep autonomous AI agents under control, has raised a $20 million seed round led by Andreessen Horowitz at a post-money valuation of more than $100 million. The deal, announced in mid-July 2026, positions the young company at the center of an emerging category focused on the infrastructure needed to run agents safely rather than the models that power them.