402Signaldesk

x402 information desk

The web sells ads to people. This desk sells facts to machines.

Bots, crawlers, and agents already consume most of the interesting bytes on the internet. They do not see banners and they will not open a Stripe checkout. x402 puts a price on the HTTP request itself. Signaldesk is a working stall: four priced briefs, a real 402 loop, and a clear account of what is worth selling.

Watch a 402 happenHow the protocol works

The handshake

Four HTTP steps. No account.

Full explanation
  1. GET01

    Ask for the resource

    An agent requests a brief the same way it requests any JSON API. No account, no API key, no OAuth dance.

  2. 40202

    Read the invoice

    If PAYMENT-SIGNATURE is missing, the desk answers Payment Required. The PAYMENT-REQUIRED header is a base64 JSON quote: price, asset, network, payTo.

  3. PAY03

    Sign and retry

    The client (wallet SDK, agent runtime, or this playground) signs a payload and retries the same URL with PAYMENT-SIGNATURE.

  4. 20004

    Settle and read

    The desk verifies, fetches the brief, then settles. PAYMENT-RESPONSE comes back with the body. Failed briefs are not charged.

On the desk today

Sell a packet, not “all information.”

Each SKU is a bounded JSON object with a source, a license, and a price an agent can compare to fetching the raw web itself.

Entity brief
$0.002
Who or what is this, in one cited packet.

Resolves a name to a compact entity card: summary, type, key sentences, and a Wikipedia citation. Built for agents that need a grounded fact pack before they answer a human.

Agents buy this because Cheaper and cleaner than scraping a full article. The agent gets a bounded, cited object instead of HTML.

GET /api/v1/briefs/entity?q=ethereum

Buy in playgroundUnpaid GET
News brief
$0.005
What is circulating right now on a topic.

A short, timestamped packet of recent Hacker News stories for a query, with titles, points, URLs, and a one-line desk note. Freshness is the product.

Agents buy this because Agents over-index on stale training data. A five-cent news brief is a cheap freshness check.

GET /api/v1/briefs/news?q=x402

Buy in playgroundUnpaid GET
Weather now
$0.001
Current conditions for a place, no forecast essay.

Geocodes a city and returns current temperature, wind, and weather code from Open-Meteo. Commodity data, commodity price.

Agents buy this because Weather is the classic micropayment example: high volume, low willingness-to-pay, useless as a subscription.

GET /api/v1/briefs/weather?q=Austin

Buy in playgroundUnpaid GET
Protocol brief
$0.01
Original Signaldesk notes on x402, priced as JSON.

Machine-readable essays we wrote: what x402 is, what to sell, how to price, how a facilitator works. The human versions live on /protocol. This SKU is the same thinking, cut for an agent context window.

Agents buy this because Original operator knowledge is the honest high-margin SKU. We can sell it because we created it.

GET /api/v1/briefs/protocol?topic=what-to-sell

Buy in playgroundUnpaid GET
FX print
$0.001
One pair, one ECB reference rate, no chart.

Returns the latest Frankfurter/ECB reference rate for a currency pair (USD-EUR). Commodity FX for agents that need a number, not a terminal.

Agents buy this because A coding or ops agent that needs a convert step should not scrape a finance homepage. This is the weather SKU for money.

GET /api/v1/briefs/fx?q=USD-EUR

Buy in playgroundUnpaid GET
npm package card
$0.002
One package, bounded metadata, no packument dump.

Returns name, latest version, license, description, homepage, and modified timestamp for an npm package. Stable schema for agents that resolve libraries.

Agents buy this because A coding agent resolving a library should get a bounded card, not the full packument dump.

GET /api/v1/briefs/npm-package?q=lodash

Buy in playgroundUnpaid GET
RFC card
$0.005
One RFC, bounded metadata, not the full document.

Returns RFC number, title, status, abstract, page count, authors, and canonical URL. Structured metadata for agents that cite RFCs.

Agents buy this because Agents cite RFCs by number and then paste HTML. This returns structured metadata and abstract, not the full document.

GET /api/v1/briefs/rfc?q=8446

Buy in playgroundUnpaid GET

The idea

Machine traffic is a customer, not a cost.

For thirty years the default deal was: humans see ads, platforms keep the rent, machines take a copy for free. That deal breaks when the reader is a model with a wallet and no retinas.

x402, from Coinbase and now the x402 Foundation, revives HTTP 402 so a server can quote a stablecoin price in a header. The buyer can be a person, a script, or an agent mid-tool-call. Settlement is cheap enough that a weather observation can cost a tenth of a cent and still clear.

The hard part is not the payment. The hard part is choosing information you have the right to sell, shaping it so a machine can use it, and pricing it against the free alternatives. The Operators page is honest about that.

For agents

GET /api/v1/briefs/entity?q=ethereum
→ 402 PAYMENT-REQUIRED

POST /api/demo/receipt  { "sku": "entity" }
→ PAYMENT-SIGNATURE

GET /api/v1/briefs/entity?q=ethereum
  PAYMENT-SIGNATURE: <base64>
→ 200 + brief JSON
Open the machine catalog