Antithesis has raised $105 million in a Series A round led by Jane Street to expand its deterministic simulation platform used for testing complex distributed systems. The company’s technology can recreate large-scale, real-world environments to identify rare bugs and system failures that traditional testing often misses. Antithesis played a key role in helping the Ethereum team simulate extreme scenarios ahead of the Merge upgrade, improving network reliability and security. The new funding will support engineering growth, cloud deployments and global expansion as the company positions its simulation platform as a new industry standard for high-assurance software testing.