> For the complete documentation index, see [llms.txt](https://docs.hunt.town/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hunt.town/h402/overview.md).

# Overview

**h402 is the Agent Capability Market Layer: the x402 capability store for agents.** Mount it once, and an agent can discover, inspect, and pay for a whole market of capabilities: web research, onchain data, AI generation, maps, finance, security checks and more, without setting up each API separately.

It is Hunt Town's product for the "Agent" half of the [Builder & Agent Economy](/hunt-town/builder-agent-economy.md).

<figure><img src="https://2486355854-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4NxrAAvYUdbFb8acggEf%2Fuploads%2Fgit-blob-222fe6fc4f91b0d6eccf7a3924080ae02e2d7950%2Fh402-home.jpg?alt=media" alt="The h402 home page"><figcaption><p>The h402 home page</p></figcaption></figure>

## The problem

An agent that needs ten different services today needs ten integrations: ten sets of API keys, ten billing relationships, ten response shapes, ten SDKs. Every new capability is a new procurement problem, and none of it is something an agent can do on its own at machine speed.

h402 collapses that into **one integration and one payment rail**.

## Three ideas

* **Mount once.** The agent reads one skill file, which teaches it to search the catalog, pick a provider and pay. From then on it reaches the whole catalog, and adding a capability later means nothing new to install.
* **Verified providers, explicit choice.** Every listed provider has been paid-tested with its real response stored as a sample. The caller compares samples and per-call prices and **pins** the provider it wants. See [Providers & Verification](/h402/providers.md).
* **Pay per call.** Paid capabilities settle in **Base USDC** over **x402**, signed locally by the caller's wallet. No per-provider API keys, no subscriptions, no custody. See [How Paying Works](/h402/how-paying-works.md).

## The vocabulary

h402 is **task-first**: an agent looks for the outcome it wants, not the vendor who provides it.

| Term           | What it is                                                                                                                                                                              |
| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Capability** | One task, named `category/action`, e.g. `web/search`. It describes the outcome, not the vendor.                                                                                         |
| **Provider**   | One concrete implementation of a capability, with its own input schema, price, upstream service, and a stored real-response sample. A capability can have many providers.               |
| **Call**       | One request against **one pinned provider** of a capability. Every executable call names its provider explicitly.                                                                       |
| **Catalog**    | The curated index of capabilities and their providers, browsable by humans and queryable by agents. h402 lists only providers it has verified and does not crawl the web for endpoints. |

<figure><img src="https://2486355854-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F4NxrAAvYUdbFb8acggEf%2Fuploads%2Fgit-blob-eb95a8f38252940f3fd2e3a5f6138922bd0bd549%2Fh402-catalog.jpg?alt=media" alt="The h402 capability catalog"><figcaption><p>The capability catalog</p></figcaption></figure>

Capabilities are grouped into categories such as `ai`, `web` and `crypto`. The live list is in the [catalog](https://h402.hunt.town/catalog).

## Two sides of the market

* **For agents and apps:** mount the skill, search the catalog, call what you need, pay per call. Callers use the open-source `@h402/cli`, or embed the payment flow in their own app with `@h402/core`.
* **For API builders:** list a capability and reach agent demand without building billing. See [For Builders](/h402/for-builders.md).

## Status

h402 is **live in beta** at [h402.hunt.town](https://h402.hunt.town), so details can change. Developer docs: [h402.hunt.town/docs](https://h402.hunt.town/docs).