> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mrdn.finance/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

> One API into every major AI model, priced per request and settled onchain with x402.

<div className="mrdn-hero" aria-hidden="true">
  <p className="mrdn-display">
    Decentralized

    <br />

    <span className="mrdn-display__accent">Inference</span>

    <br />

    <span className="mrdn-display-row">
      <span>Router</span>
      <span className="mrdn-eyebrow">Powered by x402</span>
    </span>
  </p>
</div>

Meridian Inference is a **decentralized inference router**. Instead of holding an
account with every model vendor, you point one client at one endpoint and pay per
request in USDC. Payment happens over [x402](/api-reference/inference/overview),
the HTTP `402 Payment Required` flow, so there is no billing portal, no monthly
minimum, and no identity check between you and the model.

## Vendors change, the API doesn't

Model ids are namespaced as `supplier/upstream-model-id`. Adding a supplier adds
rows to the catalog. It never changes your integration. Fetch
`GET /v1/inference/models` and the current catalog, pricing, modality, and
payment mechanics come back as registry data rather than constants you hardcode.

<div className="mrdn-panel mrdn-panel--dark mrdn-panel--statement">
  <p className="mrdn-display">
    A single door

    <br />

    into <span className="mrdn-display__accent">every model</span>
  </p>
</div>

## How a paid request works

<Steps>
  <Step title="Connect a wallet">
    One EIP-712 signature derives an in-session **buyer key**. The signature
    moves no funds and the key never leaves the browser tab. Your wallet stays
    the payer; the derived key becomes the spender.
  </Step>

  <Step title="Top up once">
    The [top-up gateway](/inference/topup-gateway) takes a gasless EIP-3009 USDC
    authorization from any of 11 supported chains and credits the buyer balance
    on Base. No ETH required on your side.
  </Step>

  <Step title="Prompt without popups">
    Each paid request receives a `402` challenge from the supplier. The derived
    key signs it silently in the page and the request is retried with a
    `PAYMENT-SIGNATURE` header. Zero wallet popups per message.
  </Step>
</Steps>

The signature budget is the point of the design:

| Action                   | Wallet popups             |
| ------------------------ | ------------------------- |
| Start a session          | `1` (derive buyer key)    |
| Top up a balance         | `1` (gasless, per top-up) |
| Send a paid chat message | `0`                       |

## Own your conversations

Chat history lives in your browser, not in a company vault. Threads stay in your
sidebar, searchable, and no platform owns them. There is no account to delete
because there was never an account to create.

<div className="mrdn-panel mrdn-panel--dark mrdn-panel--statement">
  <p className="mrdn-display">
    Your history,

    <br />

    not theirs.
  </p>
</div>

## Pricing

There is no Meridian subscription and no platform markup on chat. You sign the
supplier's own x402 challenge, and the supplier is the only payee. Per-token
rates come from the supplier catalog and are shown in the model picker next to
the per-request fee.

| What you pay          | Who receives it     |
| --------------------- | ------------------- |
| Per-token model price | The supplier        |
| Per-request x402 fee  | The supplier        |
| Meridian chat markup  | None                |
| Top-up network fees   | Settlement + bridge |

<Card title="API Reference" icon="terminal" href="/api-reference/inference/overview">
  Endpoints, request shapes, and payment kinds for the Inference API.
</Card>