x401 is an open protocol introduced by Proof on 2026-06-25 to solve Internet identity for the agentic era, providing cryptographic proof of who operates each agent and their authorized actions. The launch—announced by Pat Kinsel—names partners such as OpenAI, Google, Circle, Okta, Mattr, and Lightspark and links to x401.id.
Proof (company) launched x401 on 2026-06-25 as an open protocol for the agentic internet, branded as 'proof of who is behind every agent and what they've authorized.'
Identity on the Internet, especially in the age of agents, is a huge problem to be solved. This is the team to do it.
Pat Kinsel (@patk)
Today's a big one. @proof launches x401, the open protocol for the agentic internet in collaboration with identity leaders at @OpenAI, @Google, @circle, @okta, Mattr, @lightspark, and more. Proof of who is behind every agent and what they've authorized.
x401.id
— https://nitter.net/patk/status/2070143399261262071#m