Components

Every piece of the stack, explained.

The Stablecoin Stack is a complete system — not a single product. This page describes every major component: what it does, who operates it, and where to find the normative specification.

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The Settlement Contract

The settlement contract is the trust anchor of the entire system. It is a piece of open, auditable code deployed on a public network. It has no owner who can override its behaviour. It has no upgrade mechanism that could change its rules after deployment. It does exactly what the specification says — verifiably, publicly, permanently.

What it does:

• Verifies both cryptographic signatures on every payment.
• Transfers funds atomically — either the entire operation completes, or nothing moves.
• Distributes fees to the processor and, if applicable, the acquirer — in the same transaction as the payment.
• Records every processed payment to prevent replay.
• Registers acquirers and distributes their commissions automatically.

Operated by: the Payment Processor (deployed once per processor deployment).

Specification: SS-001, Sections 10–13.

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The Browser Wallet Extension

The Stablecoin Stack includes a browser extension wallet — the component that allows web-based merchants (e-commerce stores, web applications, games) to request payments directly from users browsing on desktop.

The extension intercepts payment requests from merchant pages, displays the payment details clearly to the user — amount, merchant, currency — and allows the user to approve or decline with a single click. Approval produces the two cryptographic signatures required by the protocol. Decline leaves the user's funds untouched.

The design is deliberately free of any association with specialised financial applications. It looks and feels like a standard digital banking tool.

What it enables:

• Any web-based merchant can trigger a payment request that appears as a clean overlay in the user's browser.
• The user reviews and confirms — or declines — without leaving the merchant's page.
• The payment submits automatically on approval. No copy-pasting addresses, no manual amounts.

Available for: Chrome, Brave, Edge, and other Chromium-based browsers.

Install the Extension

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The Mobile Wallet

The reference mobile wallet application provides the same payment experience as the browser extension, optimised for mobile devices. It is available on the Apple App Store and Google Play Store.

Merchants display a QR code or deep link. The user opens the wallet, reviews the payment request, and confirms. The wallet produces the two required signatures and submits the payment — without the user ever touching a network fee or a specialised financial instrument.

Available on:

App Store Google Play

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The Event Explorer

The Event Explorer is a public-facing service that provides structured access to settlement events on the Stablecoin Stack. It is designed for developers, operators, and anyone who wants to observe, query, or build on top of the settlement layer.

Two interfaces:

REST APIWebSocket

Query historical settlement events with flexible filters — by token, wallet address, time range, amount, or order reference. Returns structured JSON. No authentication required for public demonstration endpoints.

Useful for: reconciliation tools, accounting integrations, compliance reporting, merchant dashboards.

Subscribe to new settlement events as they confirm on the network. Events are pushed to connected clients in real time, with no polling required.

Useful for: live settlement dashboards, real-time notification systems, local matching engines.

The SDK:

A JavaScript/TypeScript SDK wraps both the REST API and the WebSocket, providing typed interfaces and utility functions. It allows a developer to go from zero to receiving live settlement data in a few lines of code.

import { ExplorerClient } from '@stablecoin-stack/explorer-sdk';

const client = new ExplorerClient('wss://explorer.stablecoinstack.org');

// Stream all new settlements in real time
client.onSettlement((event) => {
  console.log(`${event.amount} ${event.token} → ${event.recipient}`);
  console.log(`Settled in block ${event.blockNumber}`);
});

Event Explorer SDK on GitHub

Note on the Checkout Engine

The Checkout Engine — which handles merchant session creation and webhook-based reconciliation — is part of the current reference implementation and specified in SS-001. However, future versions of the specification will deprecate it in favour of a lighter integration model built directly on the Event Explorer. Merchants and processors building new integrations today should be aware of this direction.

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The Payment Gateway (Broadcast Layer)

The payment gateway is the external entry point for wallet clients. It accepts signed payment payloads over HTTPS, validates them, and routes them to the internal broadcast infrastructure that submits them to the network.

It also provides:

• Nonce retrieval — wallets can fetch the current permit nonce without a direct network call.
• Fee calculation — wallets can query the exact fee for a given payment before signing.
• Real-time status updates — a WebSocket connection allows the wallet to receive status notifications as the payment progresses through to confirmation.

Specification: SS-002 (full interface specification).

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Local deployment

Every component described above is available as part of the reference implementation on GitHub. Two Docker Compose files cover the complete stack:

# Infrastructure layer
docker compose -f docker-compose.infra.yml up -d

# Application layer  
docker compose -f docker-compose.apps.yml up -d

This brings up the settlement contract (on a local test network), the payment gateway, the event explorer, the checkout engine, and a local version of the demo store — all connected and ready to use.

GitHub Repository Try the Live Demo →

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Full component reference

Component	Operated by	Specification
Settlement Contract	Payment Processor	SS-001 §10–13
Browser Wallet Extension	Foundation (reference) / any implementer	SS-001 §5.6
Mobile Wallet	Foundation (reference) / any implementer	SS-001 §5.6
Payment Gateway	Payment Processor	SS-002
Broadcast Layer	Payment Processor	SS-001 §5.3
Event Explorer	Payment Processor / Foundation	SS-001 §5.4 + planned companion spec
Checkout Engine	Payment Processor	SS-001 §5.2 (planned: SS-004)
Basic Data Service	Payment Processor / Foundation	SS-001 §5.5 (planned: SS-008)
Merchant Dashboard	Payment Processor	SS-001 §5.7