I am looking for an experienced PHP developer to build a web-based GST compliance SaaS platform targeted at Indian e-commerce sellers, chartered accountants, and accountants. The platform will help users convert their e-commerce platform reports (Amazon, Flipkart, Meesho, etc.) into GSTR-1 Excel and JSON files, perform 2A/2B reconciliation, and convert e-commerce data into Tally-importable XML — all through a clean, subscription-based web interface. The reference product is gsttool.in. I want a similar platform built from scratch with the same core functionality. -Required Tech Stack - Backend: PHP 8.x (CodeIgniter or Laravel preferred) - Database: MySQL - Frontend: Bootstrap 5 + jQuery - Excel Processing: PhpSpreadsheet library - Payment Gateway: Razorpay (UPI, cards, netbanking, wallets) - Hosting: Linux VPS (Apache/Nginx) Core Modules to Build 1. User Authentication & Dashboard - Register, login, email verification, forgot password - User dashboard showing active tools, subscription status, usage history - Admin panel: manage users, subscriptions, revenue reports 2. GST Online Seller Tool (Main Tool — Paid) - User uploads e-commerce platform Excel report (Amazon, Flipkart, Meesho, Myntra, Snapdeal, Meesho, JioMart, etc. — minimum 10 platforms at launch) - System reads and maps platform-specific columns to GST fields (GSTIN, invoice no., taxable value, IGST, CGST, SGST, HSN, place of supply) - Classifies data into correct GSTR-1 sections: B2B, B2CS, CDNR, EXEMP, HSN Summary, Table 14 - Generates downloadable GSTR-1 Excel (government format) and GSTR-1 JSON (gst.gov.in compatible schema) - Preview/statement screen before download 3. 2A/2B Reconciliation Tool (Free) - User uploads a sample Excel file with purchase register + 2A/2B data - System matches invoices by GSTIN + invoice number, flags mismatches - Generates multi-tab Excel report: Amount Mismatched, Invoice Mismatched, Entry Pending, Return Pending, Matched, All Entry 4. eCom to Tally Tool (Paid) - Reads e-commerce platform Excel - Maps fields to TallyPrime XML voucher import format - Generates downloadable XML file importable into Tally 5. Free Utility Tools - GSTR-1 JSON to Excel converter - GST Error Report checker - GSTR-1 JSON validator - Merge Excel files utility 6. Subscription & Payments - Monthly and annual plans - Razorpay integration (UPI, cards, netbanking, wallets) - 30-day free trial for paid tools - Auto-renewal and cancellation flow - Referral/affiliate program with tracking 7. Support & Content - Help center with article collections (can be simple custom-built) - Contact/support form with email notification - Blog section (basic, for SEO) --- Key Technical Requirements - GSTR-1 JSON output must strictly follow the official gst.gov.in JSON schema so files upload without errors - Column mappings for each e-commerce platform must be configurable (not hardcoded) so new platforms can be added easily from the admin panel - All uploaded files must be stored securely and auto-deleted after processing - SSL, proper input validation, and basic security hardening required - Mobile-responsive UI What We Will Provide - Access to sample e-commerce platform Excel reports for each platform (Amazon tax report, Flipkart GST invoice report, Meesho tax report, etc.) - Official GSTR-1 Excel template and JSON schema reference - UI/UX reference (gsttool.in) - Domain and hosting - Razorpay account credentials - Ongoing feedback during development Deliverables - Fully functional, hosted SaaS web application - Source code with documentation - Admin panel - 2 weeks post-launch bug-fix support