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

# FAQ

## General Questions

<Accordion title="What is h402?">
  h402 is a thin, header-based payment primitive that integrates directly into
  HTTP interactions, enabling stateless machine-to-machine payments without
  centralized billing systems or proprietary APIs.
</Accordion>

<Accordion title="Why was h402 created?">
  Thirty-five years after HTTP's creation, the web still lacks a native,
  programmable unit of value. h402 aims to close this gap by providing a
  protocol for autonomous systems to negotiate value exchange directly.
</Accordion>

<Accordion title="How does h402 differ from traditional payment systems?">
  Unlike traditional systems that rely on credit cards, API keys or custodial
  services, h402 embeds price discovery and settlement directly in the HTTP
  request-response cycle, making it ideal for machine-to-machine transactions.
</Accordion>

## Technical Questions

<Accordion title="Does h402 require a database?">
  The core protocol is stateless, but the facilitator service requires Redis for operational purposes and uses a database for storing transaction hashes.
</Accordion>

<Accordion title="Which blockchains are supported?">
  h402 is chain-plural by design. The facilitator currently supports:

  * EVM chains (Ethereum, Base, BSC)
  * Solana mainnet
  * Future chains will be added through the extensible architecture
</Accordion>

<Accordion title="What happens if a payment fails?">
  The protocol includes verification and settlement steps. The facilitator service handles payment verification and settlement, with built-in error handling.
</Accordion>

## Implementation Questions

<Accordion title="Do I need to modify my existing HTTP service?">
  No major modifications are needed. h402 works as a thin gateway in front of
  your service, handling payment negotiation while your core logic remains
  unchanged.
</Accordion>

<Accordion title="What's the role of the Facilitator?">
  The Facilitator is a critical service that:

  * Verifies payment payloads across supported chains
  * Handles transaction settlement
  * Provides health monitoring and backup functionality
  * Manages chain-specific complexities
    It requires proper configuration including private keys, RPC endpoints, and Redis for operation.
</Accordion>

<Accordion title="How do I handle high-volume scenarios?">
  The facilitator service is designed for production use with:

  * Redis-backed operations
  * Automated database backups to S3
  * Health monitoring endpoints
  * Docker containerization support
  * Configurable backup retention and scheduling
</Accordion>

## Security Questions

<Accordion title="How are payments validated?">
  Payments are validated through the facilitator's `/verify` endpoint, which checks payment proofs and requirements including:

  * Token specifications (address, type, decimals)
  * Amount requirements
  * Network/chain validation
  * Payment expiration
</Accordion>

<Accordion title="Can payments be replayed?">
  No. The facilitator service validates each payment payload, checking each transaction against the database, additionally there are other protocol built-in security features.
</Accordion>

<Accordion title="How are API keys and secrets handled?">
  The facilitator service requires secure configuration through environment variables including:

  * Private keys for signing
  * Admin tokens for protected endpoints
  * S3 credentials for backups
  * Redis connection details

  These should be properly secured in production environments.
</Accordion>

## Use Cases

<Accordion title="Is h402 suitable for subscription services?">
  Yes. The payment requirements system supports flexible payment schemes including: `exact` and soon to be introduced `upto`, `prepaid`, `streamed`, `subscription`, `postpaid`.
</Accordion>

<Accordion title="Can h402 handle micropayments?">
  Yes, it supports precise payment amounts through:

  * Token-specific decimal handling
  * Smallest unit amount formatting
  * Support for various token types
  * Chain-specific amount representations
</Accordion>

<Accordion title="Does h402 work for human users too?">
  While optimized for machine-to-machine payments, h402 works with any system capable of:

  * Generating valid payment payloads
  * Interacting with HTTP APIs
  * Meeting payment requirements
  * Processing base64 encoded payloads

  We do also provide utils for client-side integration and human interactions.
</Accordion>

## Development & Support

<Accordion title="Where can I find example implementations?">
  Check our [Integration Examples](/h402/examples) page for real-world usage
  patterns and the [Quickstart Guide](/h402/quickstart) for basic setup
  instructions.
</Accordion>

<Accordion title="Is h402 production-ready?">
  Yes, the facilitator service is production-ready with:

  * Docker and docker-compose support
  * Comprehensive environment configuration
  * S3-compatible backup system
  * Health monitoring endpoints
  * Redis integration for reliability
</Accordion>

<Accordion title="How can I contribute?">
  h402 is fully open source. You can:

  * Contribute to the core protocol
  * Build integrations and tools
  * Share implementation feedback
  * Propose new payment schemes
</Accordion>