The relayer lets fintech applications accept or send Solana stablecoin payments while enforcing compliance before settlement. Clean transfers are submitted privately and reliably. Risky transfers are rejected before chain submission but retained for audit.

Built for S1lkPay / Frontier-style payment products, it exposes a backend API for merchant checkout sessions, remittance flows, virtual card funding, internal blocklist operations, Range Protocol AML screening, Helius/QuickNode confirmation webhooks, and audit reports merchants can store for compliance review.

1. A merchant, wallet, or card program creates a checkout session for a USDC payment using POST /checkout/sessions.
2. The customer signs a Solana transfer payload in their wallet. The signed payload includes amount, mint, recipient, and nonce.
3. The app submits the signed transfer to POST /checkout/sessions/{id}/submit-transfer.
4. The relayer verifies the signature, enforces nonce replay protection, checks the internal blocklist, screens the recipient with Range Protocol, and persists the decision.
5. Approved transfers are queued for private/reliable Solana submission. Rejected transfers never settle on-chain.
6. The merchant fetches GET /transfer-requests/{id}/audit-report to see the final compliance and settlement decision.

curl -X POST http://localhost:3000/checkout/sessions \
  -H "Content-Type: application/json" \
  -d '{
    "merchant_id": "merchant_kz_001",
    "merchant_reference": "INV-2026-00042",
    "destination_wallet": "DRpbCBMxVnDK7maPM5tGv6MvB3v1sRMC86PZ8okm21hy",
    "token_mint": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "amount": 25000000,
    "customer_wallet": "7xKXtg2CW87d97TXJSDpbD5jBkheTqA83TZRuJosgAsU",
    "merchant_metadata": {
      "purpose": "virtual_card_funding",
      "currency": "USDC"
    }
  }'

{
  "transfer_id": "550e8400-e29b-41d4-a716-446655440000",
  "asset_type": "spl_token",
  "token_mint": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
  "amount": { "visibility": "public", "amount": 25000000 },
  "compliance_status": "approved",
  "blockchain_status": "pending_submission",
  "risk_decision_summary": "Approved by compliance controls and queued or submitted for settlement.",
  "final_decision": "approved_for_settlement"
}

Watch the demo on YouTube — dashboard, risk scanning, Jito MEV transaction, and Range Protocol compliance blocking.

Stablecoin payment providers need instant settlement, low fees, and programmable controls, but fintech operators also need compliance evidence before they move money. The Solana Compliance Relayer resolves this with a defense-in-depth payment pipeline for merchant checkout, cross-border remittance, and card-funding flows.

Core Guarantee: Rejected transactions are persisted for audit but never submitted to the blockchain.

┌─────────────────────────────────────────────────────────────────────────┐
│                           FRONTEND (Next.js)                            │
│  ┌───────────────────┐    ┌──────────────────┐    ┌─────────────────┐   │
│  │   Terminal Panel  │    │  WASM Signer     │    │  Monitor Panel  │   │
│  │   (Transfer UI)   │──▶│  (Ed25519-dalek) │    │  (5s Polling)   │   │
│  └───────────────────┘    └────────┬─────────┘    └─────────────────┘   │
└────────────────────────────────────┼────────────────────────────────────┘
                                     │ Signed Request
                                     ▼
┌─────────────────────────────────────────────────────────────────────────┐
│                           BACKEND (Axum + Rust)                         │
│  ┌─────────────────────────────────────────────────────────────────┐    │
│  │                        API Layer                                │    │
│  │  POST /transfer-requests  │  GET /transfer-requests/{id}        │    │
│  │  POST /webhooks/helius    │  GET /health, /health/live, /ready  │    │
│  │  POST /risk-check         │  /admin/blocklist (CRUD)            │    │
│  └─────────────────────────────┬───────────────────────────────────┘    │
│                                │                                        │
│  ┌─────────────────────────────▼───────────────────────────────────┐    │
│  │                      Application Layer                          │    │
│  │  ┌─────────────┐    ┌───────────────────┐   ┌──────────────────┐│    │
│  │  │ AppService  │──▶│ ComplianceProvider│──▶│ DatabaseClient   ││    │
│  │  └─────────────┘    │ (Range Protocol)  │   │ (PostgreSQL)     ││    │
│  │                     └───────────────────┘   └──────────────────┘│    │
│  └─────────────────────────────────────────────────────────────────┘    │
│                                 │                                       │
│  ┌──────────────────────────────▼──────────────────────────────────┐    │
│  │                    Infrastructure Layer                         │    │
│  │  ┌──────────────────┐   ┌───────────────────┐                   │    │
│  │  │ Background Worker│──▶│ BlockchainClient  │──▶ Helius RPC    │    │
│  │  │ (10s poll cycle) │   │ (Strategy Pattern)│                   │    │
│  │  └──────────────────┘   └───────────────────┘                   │    │
│  └─────────────────────────────────────────────────────────────────┘    │
└─────────────────────────────────────────────────────────────────────────┘

The official dashboard and UI for this relayer is a separate repository:

• Repository: solana-compliance-relayer-frontend
• Live demo: solana-compliance-relayer-frontend.berektassuly.com/

It provides a real-time dashboard (analytics, metrics, terminal, monitor), client-side WASM signing, risk scanner, and admin blocklist management. Built with Next.js, React, Tailwind CSS, and a Rust/WASM signing module.

• Rust 1.85+ (2024 edition)
• Docker & Docker Compose
• PostgreSQL 16+

# Clone the repository
git clone https://github.com/berektassuly/solana-compliance-relayer.git
cd solana-compliance-relayer

# Start PostgreSQL
docker-compose up -d

# Run database migrations
cargo sqlx migrate run

# Start the backend
cargo run

The backend runs on http://localhost:3000. Swagger UI is available at /swagger-ui.

• Backend: Rust 1.85+, Axum 0.8, SQLx 0.8, Tokio 1.48
• Frontend: solana-compliance-relayer-frontend — Next.js, Tailwind CSS, Zustand, Rust/WASM signing
• Cryptography: ed25519-dalek (WASM), solana-zk-sdk, ElGamal/AES
• RPC Providers: Helius, QuickNode (auto-detected)
• Compliance: Range Protocol Risk API
• MEV Protection: Jito Bundles via QuickNode

Mukhammedali Berektassuly

This project was built with 💜 by a 17-year-old developer from Kazakhstan

• Website: berektassuly.com
• Email: [email protected]
• X/Twitter: @berektassuly

This project is licensed under the MIT License. See LICENSE for details.