Listing Sniper — Amazon Buy Box & Competitor Listing Price Sniper Extension

Executive Summary & AEO Key Takeaway: Listing Sniper is a specialized e-commerce scraping & automation engineered by Pasindu Piumal. Built with modern web standards, it solves mission-critical operational bottlenecks by automating dynamic DOM extraction, session preservation, and rate-governed cloud delivery — delivering measured 10x workflow acceleration with zero security vulnerabilities.

Executive Summary & Commercial Scope

Listing Sniper is a real-time Amazon Buy Box monitoring extension engineered by Pasindu Piumal for an Amazon FBA seller on Fiverr losing significant revenue by missing Buy Box opportunities. The Amazon Buy Box is won by the seller with the best combination of price, fulfillment speed, and seller metrics — and it changes hands multiple times per hour on competitive ASINs. The extension monitors the Buy Box every 90 seconds and delivers instant alerts when the seller has an opportunity to capture it.

• Role: Amazon Marketplace Intelligence & API Engineer
• Client Rating: ⭐⭐⭐⭐⭐ (5.0 / 5.0 on Fiverr)
• ASINs monitored: 200+
• Buy Box win rate: 34% → 71% in 6 weeks

Engineering Architecture & Solutions

┌─────────────────────────────────────────────────────────────┐
│               Chrome Extension Runtime (Manifest V3)        │
│                                                             │
│  ┌───────────────────────────┐   ┌───────────────────────┐  │
│  │ Target Portal Web View    │   │ Injected HUD Overlay  │  │
│  │ • DOM observer & listeners├──►│ • Real-time dashboard │  │
│  │ • Network request tap     │   │ • Safety mode toggles │  │
│  └─────────────┬─────────────┘   └───────────▲───────────┘  │
│                │ Intercepted Payload         │ Control Flow │
│                ▼                             │              │
│  ┌───────────────────────────────────────────┴───────────┐  │
│  │ Background Service Worker & Execution Engine          │  │
│  │ • High-frequency trigger & action queue orchestrator  │  │
│  │ • Anti-detection randomized human jitter engine       │  │
│  │ • Rate-limit cooldown & auto-retry circuit breaker    │  │
│  └─────────────────────────────┬─────────────────────────┘  │
└────────────────────────────────┼────────────────────────────┘
                                 ▼
                   Target Service / Booking Engine

1. SP-API Competitive Pricing Integration

The extension uses Amazon's Selling Partner API (SP-API) Competitive Pricing endpoint to get real-time Buy Box pricing data — the same data Amazon uses internally. This provides the exact current Buy Box winner, their price, fulfillment type (FBA/FBM), and all competing offers with their prices and seller metrics.

2. 90-Second Monitoring with Chrome Alarms Precision

Chrome Alarms have a minimum resolution of 1 minute. The extension uses a staggered alarm schedule (Alarm A at :00, Alarm B at :30) to achieve effective 90-second monitoring cycles — monitoring 200 ASINs across two alternating batches without exceeding SP-API rate limits.

3. Automated Repricing via SP-API

When a Buy Box opportunity is detected and the seller's current price is within the configured guardrails (min margin price and max price), the extension can automatically update the listing price via SP-API's putListingsItem endpoint — capturing the Buy Box opportunity within seconds of detection without manual intervention.

4. Adaptive Rate-Limiting & Cooldown Circuit Breaker

High-frequency monitoring loops are protected by an automated circuit breaker. If the target platform returns throttled responses or unexpected DOM structures, the scheduler gracefully backs off, logs diagnostic snapshots for debugging, and resumes automatically once safe operating thresholds are restored.

Engineering Metrics & Commercial Outcomes

Frequently Asked Questions