Green Harbor LabsMost API monetization stacks are built around accounts, subscriptions, and human checkout flows. Agent and machine clients need a protocol-native way to pay per request without custom billing infrastructure.
Product
In DevelopmentPaygate
Spring Boot starter for Lightning payment-gated APIs
Paygate lets Spring Boot developers protect endpoints with a single annotation, issue HTTP 402 payment challenges, and accept Bitcoin Lightning credentials through L402 or the draft Payment authentication flow.
Paygate auto-configures Spring Boot filters, protocol handlers, Lightning backends, credential validation, and observability. Developers add `@PaymentRequired`, configure LNbits or LND, and unpaid requests receive a 402 challenge instead of protected content.
As agents consume more APIs directly, payment and authorization need to become programmable, metered, and machine-readable. Paygate gives Java teams a concrete path to sell API access over Lightning without building the payment protocol layer from scratch.
Built with Paygate
Real services using the starter
Paygate Agent Trust
A Spring Boot reference service that sells signed agent trust reports behind Paygate payment challenges.
Paygate Agent Trust exposes free catalog and quote APIs, then protects trust report generation with Paygate. Program clients can request a report, receive a Lightning payment challenge, pay the invoice, and retry for a signed JSON response.
Who it is for
- Backend engineers
- Spring Boot teams
- API developers
- Agent platform builders
- AI infrastructure teams
- Lightning application builders
Use cases
- Protect premium API endpoints behind Lightning payments
- Add pay-per-use pricing with `@PaymentRequired` annotations
- Serve L402 and Payment challenges from the same endpoint
- Use dynamic pricing for expensive AI or data operations
- Integrate payment validation into Spring Security filter chains
Features
- Single-dependency Spring Boot starter for Paygate auto-configuration
- Annotation-driven endpoint protection with `@PaymentRequired`
- Dual-protocol support for L402 and MPP with multiple `WWW-Authenticate` headers
- LNbits and LND Lightning backend modules
- Dynamic pricing through `PaygatePricingStrategy`
- Spring Security integration with authentication provider, filter, and token support
- Delegation caveats for path, method, and client IP restrictions
- Micrometer metrics, Actuator health integration, and `/actuator/paygate` runtime status
- Test mode for local development without a real Lightning node
- Fail-closed behavior when the Lightning backend is unavailable
- Macaroon V2 compatibility with Go macaroon tooling