> ## Documentation Index
> Fetch the complete documentation index at: https://docs.0xarchive.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Start Build or Pro access via x402 USDC payment

> 0xArchive API reference for Start Build or Pro access via x402 USDC payment. Includes route metadata, schemas, examples, and implementation notes.

<Info>
  **x402 payment flow.** Send the signed `payment-signature` header required by this operation instead of `X-API-Key`. See [wallet access and x402](/wallet-automation), then review [REST authentication exceptions](/rest-api/authentication).
</Info>

[Operation schema](/schemas/operations/web3-subscribe)

<Accordion title="Shared request rules">
  * [Rate limits and credits](/rate-limits)
  * [HTTP responses and status codes](/responses)
  * [Errors and request IDs](/errors)
</Accordion>

<Accordion title="Machine schema">
  [Open the generated operation schema](/schemas/operations/web3-subscribe) for machine-readable request and response details.
</Accordion>


## API Specification

The full API specification for this endpoint is available in the [documentation index](https://docs.0xarchive.io/llms.txt).


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