STEPN Marketplace Bot

Overview

Full-stack application for automated monitoring and instant purchasing on the STEPN NFT marketplace. Headless browser automation with Playwright, rule-based buying system, parallel scraping of three NFT categories, multi-step purchase process with 2FA handling, and real-time web dashboard. In daily production use.

Tech Stack

Architecture Highlights

• Modular NestJS architecture with 6 domain modules
• Parallel browser architecture: 3 scraper pages in the same BrowserContext
• PurchaseLockService: Global FIFO lock serializes all purchases without busy-wait
• Event-driven architecture with Socket.io for loose coupling
• Monorepo with pnpm workspaces and shared types package
• Docker Compose with 5 containers (API, frontend, nginx, MongoDB, Redis)

Key Features

• Parallel scraping of 3 NFT categories on separate browser tabs
• Rule-based buying system with combinable filters and short-circuit logic
• Multi-step fully automatic purchase process with 2FA handling
• Real-time web UI with WebSocket-based live updates
• Network response interception instead of UI scraping for maximum speed
• Stealth plugin for anti-bot detection circumvention

Challenges & Solutions

• Browser automation with anti-bot circumvention: stealth plugin, resource blocking, React-compatible input
• Speed optimization: network interception, parallel scraping, short-circuit logic
• 12-step purchase process: PurchaseLock, TOTP generation with period change handling, three-stage success verification
• SPA session management: 2-stage validation (cookie check + server-side verification) before every scrape cycle