Hi HN. I m Chris Bergeron, an SRE by profession but a general technologist in my spare time. Projects I ve built have been featured in books, frontpaged on news aggregators and chronicled on my blog.Today, I m announcing https://username.md !username.md is a single identity URL: username.md/ your name - that content-negotiates on the `Accept` header. It serves an HTML profile page; an agent or curl gets Markdown, JSON, JSON-LD, or a JWT. The same URL serves different representations based on request header. So the page a human reads and the data a machine parses never drift apart.The interesting part is that every response can be signed and verified. Each handle gets an ED25519 keypair (private key AES-GCM-wrapped at rest), publishes a did:web document, and serves RFC 9421 signed responses. Claims about you — GitHub, a domain you control, an ATProto handle — are W3C Verifiable Credentials, verified before they re shown (e.g. domain ownership via a DNS-TXT challenge). So this is really them can be confirmed by a machine instead of taken on faith.It can also bridge the identities you might already use, like ATProto because it supports did:web. Every username.md handle is a valid Bluesky identity root, and you can even import from Keybase.Why we built it: usernames on every platform are rented. The platform owns the namespace, the verification badge, and the audience. As agents start conducting business on our behalf, who is this, and can I prove it becomes an accountability and governance issue. I wanted an identity surface that s mine, portable, and cryptographically verifiable; which anyone can have if they own a domain (mine is https://chrisbergeron.com, feel free to review the metadata). But I wanted to bring DID:web functionality to the mass market. You can get a username for yourself, for an agent, or multiple agents.Free tier gets you a public, signed profile at your handle. Pro ($49/yr; coming soon!) adds you@username.md email forwarding with per-service aliases, custom CSS, and an MCP endpoint so an agent can query your profile as tools.The stack is a Python identity kernel, per-user keys, CloudFlare in front of the origin. Infra is hosted at AWS, built multi-region for HA but only one region is live right now. I m a platform and security guy, so the frontend and marketing copy was augmented with AI.I m sure you ll find bugs and typos but hopefully few inconsistencies. It s an MVP and I would never be able to ship if I kept engineering, tweaking and optimizing. So, here it is for you to enjoy, explore, and build upon - today.I have some really exciting things on the roadmap so I hope you join me and start building on top of username. The capabilities are super exciting and we re just getting started.This may be the beginning of a new category: SSO as a Service.