Green Harbor Labs

AI-assisted engineering studio

Building software at the edge of AI and engineering craft.

Green Harbor Labs creates developer tools, backend systems, prototypes, and web products with production-grade thinking.

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What Green Harbor Labs Builds

Practical software products and experiments using modern engineering practices, AI-assisted workflows, and a bias toward shipping.

AI-Assisted Applications

Products and tools that use AI as a core capability, from agent workflows to intelligent interfaces.

Developer Tools

Utilities, automation, and workflows that help engineers plan, build, test, and ship faster.

Web Products

Fast, polished browser products with clean UX, modern frontend architecture, and scalable foundations.

Prototypes & Experiments

Focused builds that explore product ideas, AI workflows, tools, and technical concepts.

Featured Project

Paygate

Spring Boot starter for Lightning payment-gated APIs

In Development

Developer Tool / Spring Boot Starter

Paygate is a Spring Boot starter that adds L402 and MPP payment-gated authentication to Java 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.

  • Java 25
  • Spring Boot
  • Spring Security
  • L402
  • MPP
  • LNbits
  • LND
  • Macaroons
  • Gradle
  • Maven Central
First service using Paygate

Paygate Agent Trust

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.

View PaygateView Paygate on GitHubRead Paygate docs
Problem

Most 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.

Solution

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.

Why it matters

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.

Approach

AI as an Engineering Multiplier

Green Harbor Labs uses AI across the software delivery lifecycle to move faster while keeping architecture, security, and maintainability in focus.

  1. Idea
  2. PRD
  3. Architecture
  4. Build
  5. Test
  6. Ship
  7. Iterate

Capabilities

Engineering Capabilities

A practical mix of frontend, backend, AI workflow, cloud, and product engineering experience.

Frontend

React · Next.js · TypeScript · Tailwind CSS · responsive UI · animation

Backend

Java · Spring Boot · REST APIs · event-driven systems · data modeling

AI Workflows

AI coding agents · planning workflows · model-assisted development · automation

Cloud & Data

AWS · SQS · S3 · relational databases · graph databases · batch processing

Product Engineering

PRDs · prototypes · MVPs · internal tools · technical documentation · QA workflows

About

About Green Harbor Labs

Green Harbor Labs is the software engineering home of Mark Hammond, a place for building, testing, and shipping AI-assisted software products, experiments, and tools.

The lab focuses on practical software: useful products, clean systems, thoughtful architecture, and fast iteration powered by modern AI workflows.