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NexusGuard - Sales Tax Compliance Monitor
Full Stack SaaS

NexusGuard - Sales Tax Compliance Monitor

Automated sales tax nexus monitoring for Shopify stores across all 50 states

React.jsTypeScriptViteNode.jsExpressSupabasePostgreSQLShopify APITailwind CSS

NexusGuard solves a critical compliance challenge for e-commerce sellers: Sales Tax Nexus Management. When Shopify store owners sell products across multiple U.S. states, they face complex sales tax compliance requirements. Each state has different "economic nexus" thresholds that trigger tax obligations.


The Problem:

  • Complex Thresholds: Each state has different rules ($100K-$500K in revenue OR 200+ transactions)
  • Legal Consequences: Missing nexus establishment can result in penalties, back taxes, and legal issues
  • Manual Tracking: Manually calculating sales per state is time-consuming and error-prone
  • Multi-State Complexity: Businesses may need to track compliance across 50+ states simultaneously
  • Filing Deadlines: Once nexus is established, businesses must file regular tax returns (monthly/quarterly)

    • The Solution:

    NexusGuard is an automated sales tax nexus monitoring platform that helps Shopify sellers:

    1. Automatically Track Sales - Syncs with Shopify to track revenue per state

    2. Monitor Thresholds - Calculates when you cross state nexus thresholds

    3. Get Alerts - Notifies you immediately when nexus is established

    4. Filing Reminders - Reminds you of upcoming tax filing deadlines

    5. CPA-Ready Reports - Generates compliance reports for your accountant


    Key Features:

  • Shopify OAuth integration for seamless store connection
  • Multi-state sales tracking with visual dashboards
  • Real-time nexus threshold monitoring across all 50 states + DC
  • Automated alerts when thresholds are crossed
  • Filing deadline reminders
  • CSV/JSON export for CPA sharing
  • Multi-store support
  • Free and paid subscription plans

    • Use Cases:

  • Shopify store doing $300K/year: needs to know when they cross economic nexus in California ($500K threshold) vs. Texas ($100K). NexusGuard tracks each state and alerts before compliance is triggered.
  • Multi-store operator with 5 Shopify stores: consolidates sales by state across all stores, exports one report for CPA at tax time.
  • Brand expanding from regional to national: monitors new states as sales grow, gets filing reminders when nexus is established.

    • Usage Example:

    Sarah runs a skincare brand on Shopify, selling $450K/year. She has customers in 35 states. She connects NexusGuard via OAuth—no manual data entry. The dashboard shows she crossed nexus in California (2 months ago) and is 78% toward Texas. She gets an email: "You established nexus in Texas. File your first return by March 15." She exports a CSV for her CPA and files on time. Without NexusGuard, she would have missed Texas and faced penalties.


    Technical Stack:

    Built with React, TypeScript, Node.js, Express, and Supabase (PostgreSQL). Features a modern, responsive UI with real-time dashboard updates, background job processing for order synchronization, and comprehensive state sales tracking.

    Interested in building something like this?

    Get In Touch

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