Server middleware
Drop the QBT Labs x402 middleware on a paid endpoint. Define pricing, accepted assets, and recipient. The server returns 402 with machine-readable pricing, verifies the signed retry, and emits a structured receipt.
x402 payment infrastructure for AI agents: the QBT Labs implementation
x402 is an open protocol that turns the HTTP 402 status code into a payment handshake for autonomous agents. QBT Labs ships an MIT-licensed x402 implementation, plus the surrounding infrastructure — payment channels, encrypted vault, signer isolation, and policy controls — needed to run agent payments in production.
Capability
QBT Labs (implementation)
x402 (open protocol)
Protocol layer
Implements the x402 HTTP 402 flow in @qbtlabs/x402 (MIT)
x402 is the open protocol QBT Labs implements and extends
Server SDK
TypeScript server middleware for pricing, verification, and receipts
Reference implementations require teams to assemble pricing, verification, settlement themselves
Client SDK
Agent-side client with signer, retry, and budget hooks
Most agent stacks need a custom integration
Channels for high volume
AMP-style payment channels for sessions with repeated calls
x402 alone settles per request
Spend policy
Per-agent caps, daily limits, recipient allowlists, chain restrictions
Not part of the x402 protocol itself
Signer security
Encrypted vault and process-isolated signer over Unix socket
Wallet management is left to the integrator
Receipts
Structured receipt: request ID, amount, asset, chain, recipient, status
Receipt format depends on the implementation
Chain support
Base, Solana, Cardano; pluggable for new chains
Chain support depends on the facilitator and server implementation
Facilitator
Bring your own facilitator or use a public one
Facilitator choice is part of the protocol design
License
MIT open source
x402 is an open standard; implementations vary
Agent client
The client signs payment authorizations, retries cleanly, and checks budget before paying. It hooks into the QBT Labs vault and policy engine so an agent cannot exceed limits or pay an unapproved recipient.
Channels for volume
For sessions with hundreds or thousands of calls, AMP-style channels deposit once, sign many off-chain payments, and settle periodically — keeping the hot loop off-chain.
What x402 covers vs what QBT Labs adds
x402 protocol
- HTTP 402 status code as the payment handshake
- Server-defined pricing in the 402 response
- Signed payment authorization on retry
- Facilitator-mediated settlement
QBT Labs production layer
- Pricing, receipts, and audit log formats
- AMP-style channels for high-volume sessions
- Encrypted vault and process-isolated signer
- Per-agent budgets, allowlists, chain restrictions
- Multi-chain verification: Base, Solana, Cardano
Ship an x402 endpoint that survives production
QBT Labs gives API providers and agent builders the x402 implementation, channels, vault, and policy engine they need without rebuilding billing or signer infrastructure from scratch.