> ## Documentation Index
> Fetch the complete documentation index at: https://docs.x402x.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# x402x

> Types, schemas, and low-level utilities (typically used indirectly by other packages)

## Overview

`x402x` is the core package of the x402x protocol, extending the x402 core with foundational types for EIP-3009, EIP-2612, and Permit2, Zod schemas, EVM utilities, and verification logic. It’s typically used indirectly by higher-level packages (`x402x-fetch` / `x402x-server` / `x402x-facilitator` / `x402x-detector`), but can also be imported directly when you need custom orchestration.

### Capabilities

* Types and Zod schemas: `PaymentRequirements`, `PaymentPayload`, `Response402`, etc.
* EVM utilities: EIP-2612 Permit, EIP-3009, and Permit2 signing and verification
* Validation logic: amount/network/signature/nonce checks
* Modular design: shared, schemes, client, verify, facilitator, types

## Install

```bash theme={null}
npm i x402x@beta
```

## Modules and exports

```ts theme={null}
import type { PaymentRequirements, PaymentPayload, Response402 } from "x402x/types";
```

Other common entry points:

```ts theme={null}
// Shared EVM utilities
import { getChainId, getNetworkName } from "x402x/shared/evm";

// Scheme utilities (exact)
import { createExactPaymentRequirements, validateExactPayment } from "x402x/schemes";

// Verification utilities
import { verifyPermitSignature, verifyEIP3009Signature, verifyPermit2Signature } from "x402x/verify";
```

## When to use directly

* Import base types/utilities when you need custom verification or orchestration
* When building a facilitator

## Types and schemas (example)

```ts theme={null}
// PaymentRequirements
interface PaymentRequirements {
  scheme: string;              // "exact"
  network: string;             // "bsc-testnet"
  maxAmountRequired: string;   // amount (wei)
  asset: string;               // token address
  paymentType?: string;        // permit/eip3009/permit2
  resource?: string;
  description?: string;
  mimeType?: string;
  maxTimeoutSeconds?: number;
  outputSchema?: Record<string, unknown>;
  extra?: Record<string, unknown>;
}
```

```ts theme={null}
// Response402
interface Response402 {
  x402Version: number;           // 1
  accepts: PaymentRequirements[]; // list of acceptable payment requirements
  error?: string;
}
```

Zod validation:

```ts theme={null}
import { PaymentRequirementsSchema, Response402Schema } from "x402x/types";

const validated = PaymentRequirementsSchema.parse(unknownData);
const safe = Response402Schema.safeParse(unknownResp);
```

## Usage examples

### Create a 402 response

```ts theme={null}
import type { Response402, PaymentRequirements } from "x402x/types";

function create402Response(accepts: PaymentRequirements[], error?: string): Response402 {
  return { x402Version: 1, accepts, error };
}
```

### EVM utilities

```ts theme={null}
import { getChainId, getNetworkName } from "x402x/shared/evm";
const id = getChainId("bsc-testnet"); // 97
const name = getNetworkName(97);      // "bsc-testnet"
```

## Best practices

* Use Zod schemas to validate external inputs at runtime
* Leverage type inference to reduce manual type maintenance
* Import modules on demand to avoid bundling everything

## Relationship to other packages

* fetch: generates payment headers and retry logic; depends on core types
* server: orchestrates creation/verification/settlement; depends on verification and types
* facilitator: defines payment processing interfaces and return types
* detector: depends on a small subset of EVM/type utilities

## Resources

* Source: `https://github.com/WTFLabs-WTF/x402x/tree/main/typescript/packages/x402x`
* Standards: EIP-2612, EIP-3009, Permit2