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# Gateway

:::warning
The Gateway API is experimental and may change in future releases.
:::

## Overview

A Tempo Gateway is one HTTP API where a Tempo wallet is the only account. It serves AI inference, private
object storage, key-value state and sandboxed CPU or GPU compute, and charges each call through an
[MPP](https://mpp.dev) payment session funded by the caller's wallet. There is no signup, no billing setup
and no API key to provision: whoever can pay can call it.

Viem's [`gatewayActions`](/tempo/utilities/Gateway) give you typed methods for every route. A Client with an
account pays any `402 Payment Required` the Gateway answers: a local account through
[`mppx`](https://mpp.dev/sdk/typescript), and [Tempo Wallet](/tempo/guides/gateway/tempo-wallet) through the Accounts SDK.

### Quickstart

1. Create or load an account and fund it with a little OUSD (send it from any wallet; at $0.0001 a read, $1 covers
   10,000 key-value reads).
2. Install `mppx` (`npm i mppx`), which pays the Gateway's `402` challenges with that account.
3. Extend a Client with `gatewayActions()` and call it.

```ts twoslash
import { privateKeyToAccount } from 'viem/accounts'
import { createClient, gatewayActions } from 'viem/tempo'

const account = privateKeyToAccount(process.env.PRIVATE_KEY as `0x${string}`)
const client = createClient({ account }).extend(gatewayActions())

const { text } = await client.ai.generateText({
  maxOutputTokens: 256,
  model: '@cf/zai-org/glm-5.3',
  prompt: 'Say hello in five words.',
})
```

An unfunded account throws `Gateway.InsufficientFundsError` with its balances before anything is signed.
For a user's wallet instead of a key you hold, see [Use with Tempo Wallet](/tempo/guides/gateway/tempo-wallet).

### How Payment Works

1. Your app calls a paid route, such as `client.ai.generateText`.
2. The Gateway answers `402` with an MPP challenge naming its price, currency and recipient.
3. `mppx` opens (or reuses) a payment channel from your wallet and retries the request with a signed voucher.
4. The Gateway serves the request. Metered routes (AI tokens, compute seconds) reserve the most a call can cost
   and credit the unused part back to the channel.

Your data is scoped by chain, paying wallet and **app** (the `Gateway-App` header viem sends from `app`), so
two apps paid by the same wallet never see each other's keys or objects.

## See More

<Cards>
  <Card icon="lucide:wallet" title="Connect & Pay" description="Pay from a local account, a Tempo Wallet access key, or a Gateway API key." to="/tempo/guides/gateway/connect" />

  <Card icon="lucide:app-window" title="Use with Tempo Wallet" description="Let users pay from Tempo Wallet with an access key they approve once." to="/tempo/guides/gateway/tempo-wallet" />

  <Card icon="lucide:sparkles" title="Run Inference" description="Generate, stream and embed text, metered per token." to="/tempo/guides/gateway/ai" />

  <Card icon="lucide:database" title="Store Objects & State" description="Keep files in a bucket and JSON state in a versioned key-value store." to="/tempo/guides/gateway/storage" />

  <Card icon="lucide:cpu" title="Run Sandboxes" description="Start CPU or GPU sandboxes, run commands and long jobs, and pay by the second." to="/tempo/guides/gateway/compute" />

  <Card icon="lucide:square-function" title="Gateway" description="Reference for gatewayActions, standalone actions and errors." to="/tempo/utilities/Gateway" />
</Cards>