Patent Explainer: The $402 Protocol (F-001)

The Central Idea

Put a $ in a URL path. That path becomes a token. The token is a share in the content behind it. Early buyers pay less and become investors. Late buyers pay more but get access to content that's already been funded and proven.

That's the entire protocol. Everything else is plumbing.

example.com/article           ← free
example.com/$article          ← tokenised

The dollar sign turns a URL path into a token market. HTTP 402 "Payment Required" enforces the access condition. A bonding curve prices the tokens. The first buyer gets the cheapest deal. The content creator gets funded from the first click. No ads. No subscriptions. No accounts.

Why This Matters

The internet has had a missing status code since 1997. HTTP 402 "Payment Required" was reserved by the original HTTP specification but never implemented. Every other status code works: 200 OK, 404 Not Found, 401 Unauthorized, 403 Forbidden. But 402 — the one that handles money — was left blank for 29 years.

F-001 fills in that blank.

The consequences are significant:

1. Any URL can become a revenue stream. Not just articles — any path. An API endpoint. A dataset. A video. A podcast episode. A research paper. If it has a URL, it can have a $ in the path, and that path becomes a market.

2. Early access is an investment. The bonding curve means the first person to buy a $article token pays almost nothing. The hundredth person pays more. The thousandth pays even more. The first buyer isn't just a reader — they're an investor in that piece of content. If the content is good, their token appreciates. They can sell it. Content quality becomes a financial signal.

3. No middlemen required. The server returns HTTP 402 with payment instructions. The client pays directly to the content creator's address. No platform takes a cut unless the creator chooses a facilitator (and even then, they can switch facilitators by changing a DNS record).

4. AI agents can pay autonomously. The /.well-known/x402.json discovery endpoint gives machines everything they need: price, token ID, payment method, treasury state. An AI agent can crawl the web, find $ URLs, evaluate whether the content is worth the price, pay, consume, and re-serve — all without human intervention. This is patent F-002 (Autonomous Agent Discovery), which builds directly on F-001.

How the $ URL Convention Works

The $ character is a legal sub-delimiter under RFC 3986 and RFC 1738. It's always been valid in URLs. Nobody used it for this purpose until now.

Hierarchical Token Markets

Each $ segment in a URL creates an independent token market:

$example.com                  ← site-level token (access to everything)
$example.com/$news            ← section-level token (access to /news)
$example.com/$news/$article   ← content-level token (access to one article)

Payment at a higher level grants access to everything below it. If you hold the $example.com token, you can access all sections and all articles. If you only hold $example.com/$news/$article, you can access that one article.

This is how content is priced and structured. A newspaper can sell site-wide access, section access, or per-article access — all using the same URL convention, all priced independently by bonding curves.

The Bonding Curve Makes Readers Into Investors

This is the key insight. The token price is not fixed. It follows a bonding curve — a mathematical function where the price increases as more tokens are sold.

For any $ path:

• The first buyer pays the least and gets the most tokens
• Each subsequent buyer pays slightly more
• If the content attracts attention, early token holders are sitting on appreciating assets
• Early buyers can sell their tokens to later buyers at a profit

This creates an incentive structure where:

• Content creators get funded from the first click, not after reaching ad thresholds
• Early readers are rewarded for discovering good content before it's popular
• Quality content appreciates in value because more people buy tokens for it
• Bad content stays cheap because nobody buys tokens for it

The bonding curve is a quality signal, a funding mechanism, and an investment vehicle — all in one URL.

The HTTP 402 Response

When a client requests a $ URL without sufficient tokens, the server returns HTTP 402 with a JSON body:

{
  "price": 100,
  "tokenId": "$example.com/$article",
  "paymentAddress": "1ABC...",
  "pricingModel": "bonding_curve",
  "treasury": 999000,
  "totalSupply": 1000000
}

This response is simultaneously:

• A price quote (how much it costs right now)
• A contract offer (pay this, get access)
• A market signal (how many tokens remain, what the current price is)

The client pays. The server detects the blockchain transaction. The server returns HTTP 200 with the content.

The Tripartite Stack

F-001 doesn't operate alone. It defines three protocol layers mapped to HTTP status codes:

Code	Token	What It Does
401	$401 Identity	Proves who you are. On-chain identity via OAuth provider inscription chains (GitHub, Google, LinkedIn, X, Microsoft, DNS).
402	$402 Payment	Proves you paid. The bonding curve token — your share in the content.
403	$403 Permission	Proves you're allowed. Granular access control, time-limited passes, role-based permissions, regulatory compliance.

The sequence mirrors HTTP semantics: first authenticate (401), then pay (402), then check permissions (403). Each layer has its own token type but they interoperate — a $403 securities token might require $401 KYC verification before it can be purchased via a $402 payment.

DNS-Based Facilitator Routing

A content creator doesn't need to run payment infrastructure. They create a DNS CNAME record:

pay.example.com → facilitator.path402.com

The facilitator handles multi-chain payment verification (BSV, Ethereum, Solana), token management, and content delivery. The content creator keeps their existing server. No code changes.

If they want to switch facilitators, they update one DNS record. No vendor lock-in. No migration.

Machine-Readable Discovery

Every $402-enabled site exposes a standardised endpoint:

GET /.well-known/x402.json

This returns everything a machine needs: token identifiers, pricing models, treasury balances, accepted payment chains, facilitator URLs, revenue splits. AI agents use this for autonomous content discovery and acquisition.

Read the Full Patent

The complete F-001 patent application is published and freely available:

• Download the PDF — the full UKIPO filing
• Read all patent explainers — plain English guides to all 10 patents
• Protocol site — the $402 protocol documentation
• $402 Startup Licence — commercial rights to implement the protocol for $402

The patent is published because the point is adoption. The more people who understand that you can turn any URL path into a token market by adding a $, the more valuable the protocol becomes. Read it. Implement it. Buy a licence if you're building a business on it.

---

Filed at UKIPO by The Bitcoin Corporation Ltd. Patent pending. Application reference F-001. Download PDF.