Vasek Mlejnsky

Vasek Mlejnsky is the co-founder and CEO of E2B, an open-source cloud runtime that gives AI agents secure, isolated sandboxes to run code and use real tools. Raised in a small Czech town, he moved to San Francisco in 2021 through the Pioneer accelerator with his sixth-grade friend and co-founder Tomas Valenta. After pivoting through several developer-tool ideas, the pair launched E2B in 2023. By 2025 the platform was used by 88% of Fortune 100 companies and had run hundreds of millions of sandbox sessions, and E2B closed a $21M Series A led by Insight Partners.