S1lkPay x402 Bridge

x402 payment bridge that lets AI agents pay for APIs from a bank account with Solana settlement.

🚀 Live App · 🤖 Live Agent · 🎥 Video Demo · 🎤 Pitch · 📊 Pitch Deck · 📚 Docs · 🔌 Swagger

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What is S1lkPay x402 Bridge? ⚡

S1lkPay x402 Bridge lets AI agents pay for paid APIs through x402 while the user pays from a familiar bank account.

The agent does not get access to the user’s card, wallet, or full balance.
It only receives a limited session token with spending rules.

User KZT balance → Agent session token → x402 API payment → Solana settlement → Paid API response

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Problem 🤖

AI agents can use tools, APIs, data feeds, and paid services.

But payments are still hard:

Problem	Why it matters
Agents should not get card access	Too risky
Agents should not get private keys	Unsafe for users
Users do not want crypto wallet UX	Too much friction
Manual approval for every API call is slow	Breaks automation
Paid APIs need machine-friendly payments	Agents need automatic access

Core question:
How can an AI agent pay for digital services without direct access to the user’s money?

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Solution ✅

S1lkPay x402 Bridge adds a safe payment layer between the user, the agent, and the paid API.

1. User enables AI payments
2. User sets spending limits
3. User creates an agent session token
4. Agent calls an x402-protected API
5. Seller returns HTTP 402 Payment Required
6. Agent asks S1lkPay Bridge to pay
7. Bridge checks limits and balance
8. Bridge creates x402 PAYMENT-SIGNATURE
9. Seller accepts Solana payment
10. Bridge confirms payment and debits KZT

The agent can pay only through the bridge and only within the user’s limits.

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Demo Flow 🚀

1. Open the main S1lkPay frontend
2. Register or log in
3. Enable agent payments
4. Set daily and per-transaction limits
5. Create an agent session
6. Copy sessionToken
7. Open the browser agent terminal
8. Click Start
9. Run: Connect s1lk-x402-bridge
10. Paste sessionToken
11. Run: Get premium sol quote
12. Agent pays through x402
13. Seller returns paid data
14. Payment appears in history
15. Ledger shows KZT debit

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Why Solana? 🟣

Solana is part of the actual payment path.

The seller only unlocks the paid API after receiving a valid x402 payment flow using Solana settlement.

Solana value	How it helps
Fast payments	Good for agent-to-API requests
Low fees	Works for small API payments
USDC support	Fits paid digital services
x402 SVM flow	Enables HTTP 402 payments on Solana
Payment proof	Paid access depends on payment success

Without Solana settlement, the core paid API flow does not work.

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Screenshots

Main Dashboard

Agent Payment Settings

Agent Sessions

Browser Agent Terminal

Payment Detail

Ledger

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Architecture 🧩

User
  ↓
Main frontend
  ↓
apps/api
  ↓
Agent session + limits + balance check
  ↓
apps/agent-cli / browser terminal
  ↓
apps/seller returns HTTP 402
  ↓
@s1lk/x402-agent-sdk calls bridge
  ↓
Bridge creates PAYMENT-SIGNATURE
  ↓
x402 Solana settlement
  ↓
Seller returns paid data
  ↓
Bridge confirms payment and writes ledger

More details: docs/architecture.md

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Repository Structure

slkp/
├── frontend/                      # Main user application
│
└── backend/
    ├── apps/
    │   ├── api/
    │   │   └── Main NestJS backend
    │   ├── seller/
    │   │   └── x402-protected paid API
    │   ├── agent-cli/
    │   │   └── Interactive AI agent simulator
    │   └── agent-terminal-web/
    │       └── Browser terminal for demo
    │
    └── packages/
          └── agent-sdk/
             └── @s1lk/x402-agent-sdk

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Tech Stack

Layer	Technology
Main Frontend	React, Vite, TypeScript, Tailwind CSS, React Router
Browser Agent Terminal	React, Vite, xterm.js, Socket.IO
Backend API	NestJS, TypeScript, Prisma
Database	PostgreSQL
Seller API	Express, x402 middleware
Agent CLI	TypeScript
Agent SDK	TypeScript
Payments	x402
Blockchain	Solana Devnet, x402 SVM

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Quick Start

Prerequisites

• Node.js 24+
• pnpm
• PostgreSQL
• Solana Devnet USDC for treasury
• Browser with WebSocket support

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Install

git clone https://github.com/kiratonine/slkp.git
cd slkp
pnpm install

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Environment

Create environment files from examples:

cp frontend/.env.example frontend/.env
cp backend/apps/api/.env.example backend/apps/api/.env
cp backend/apps/seller/.env.example backend/apps/seller/.env
cp backend/apps/agent-terminal-web/.env.example backend/apps/agent-terminal-web/.env

Fill the required variables inside each .env file.

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Prisma

cd backend
pnpm --dir apps/api exec prisma generate --schema=./prisma/schema.prisma
pnpm --dir apps/api exec prisma migrate dev --schema=./prisma/schema.prisma

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Build

cd backend
pnpm --dir packages/agent-sdk build
pnpm --dir apps/agent-cli build
pnpm --dir apps/seller build
pnpm --dir apps/agent-terminal-web build
pnpm --dir apps/api build

cd ../frontend
pnpm build

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Run Locally

Terminal 1 — backend API:

cd backend/apps/api
pnpm start:dev

Terminal 2 — x402 seller:

cd backend/apps/seller
pnpm dev

Terminal 3 — main frontend:

cd frontend
pnpm dev

Terminal 4 — browser agent terminal:

cd backend/apps/agent-terminal-web
pnpm dev

Open:

Main app: http://localhost:5173
Agent terminal: http://localhost:5174
Swagger: http://localhost:3001/docs

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Browser Agent Commands

Use these commands in the browser terminal:

Connect s1lk-x402-bridge
Get premium sol quote

The first command connects the bridge and asks for a session token.
The second command runs the paid x402 API flow.

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Roadmap

• Auth and KZT balance
• Agent sessions and limits
• x402 seller API
• Agent SDK
• Browser agent terminal
• Two-phase payment confirmation
• Ledger after seller success
• Backend CI
• Improve payment reconciliation
• Publish agent SDK
• Integrate real S1lkPay balance
• Add seller approval flow
• Prepare mainnet treasury model

Full roadmap: docs/roadmap.md

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Docs

• Product
• Architecture
• Agent SDK
• API Docs
• Roadmap

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