Atsign

Atsign develops edge-to-edge encryption technology and secure-by-design infrastructure for agentic AI applications, providing a sovereign messaging platform where identity is verified before connections occur. The platform eliminates traditional network attack surfaces through a no-open-ports architecture, making systems invisible to Internet attackers while preventing agent-specific vulnerabilities including prompt injections, poisoning, and data exfiltration. Atsign's three core innovations include Atsigns, which are unique cryptographic identities with quantum-safe, non-custodial encryption assigned to every actor; the Atsign Platform, a sovereign messaging layer enabling encrypted peer-to-peer communications without open inbound ports; and Atsign AI Architect, a tool that guides LLMs to embed security directly into application architecture from day zero. The platform reduces infrastructure overhead by eliminating the need for WAF, IdP, CDN, reverse proxies, service mesh, guardian agents, EDR, AI-SPM, and VPNs, while accelerating MVP development from months to hours. Founded in 2019 and headquartered in San Jose, California, the company has raised approximately $11.1M in seed funding. Atsign differentiates itself through its secure-by-design agentic AI platform that eliminates open inbound ports entirely, using cryptographic identity verification and non-custodial encryption to make IoT devices and AI agents invisible to Internet attackers.