# SellerSlip — Comprehensive Technical & Operational Knowledge Base > Canonical URL: https://sellerslip.com/ > Target Audience: Indian e-commerce merchants, D2C warehouse operators, 3PL logistics managers, and marketplace sellers on Meesho, Flipkart, Amazon, and courier partners. > Technical Paradigm: 100% Client-Side WebAssembly (Zero File Uploads, Total Data Privacy). --- ## 1. Executive Overview & Problem Definition Indian e-commerce marketplaces generate shipping labels bundled with customer tax invoices on standard A4 PDF pages (595.28 x 841.89 points). When sellers dispatch tens or hundreds of parcels daily, printing full A4 sheets on laser printers consumes excessive paper and ink. Conversely, printing uncropped A4 pages on 4x6" thermal roll printers compresses the text and barcode, wasting more than 50% of the thermal sticker space on invoices and causing handheld courier barcode scanners to fail. Manual trimming with scissors is slow, error-prone, and causes dispatch bottlenecks that lead to Ready-to-Dispatch (RTD) breaches and marketplace penalties. **SellerSlip solves this problem entirely in the user's web browser:** - Extracts shipping labels using precise geometric clipping. - Completely removes or separates the customer Tax Invoice. - Formats outputs for 4x2" thermal rolls, 4x6" thermal rolls, or 4-in-1 / 2-in-1 A4 sticker sheets. - Groups identical items together using automated in-browser SKU parsing. - Guarantees 100% customer privacy: files never leave the user's computer. --- ## 2. Platform Architecture & Data Privacy Guarantee ### 2.1 WebAssembly & Client-Side Execution - PDF processing is executed locally using client-side JavaScript and WebAssembly libraries (`pdf-lib` and `pdfjs-dist`). - When a seller drops a 50-page PDF manifest into SellerSlip, the file is read into local RAM via `FileReader` and `ArrayBuffer`. - Coordinate calculations, vector path clipping, page dimension restructuring, and font preservation occur strictly on the client CPU. - Barcode lines and text elements remain 100% mathematical vectors without lossy JPEG/PNG rasterization, guaranteeing maximum 203 DPI and 300 DPI thermal print clarity. ### 2.2 Complete Privacy & Data Security - **No Cloud Uploads**: The application does not communicate with any backend server for document processing. - **Zero Document Storage**: Customer names, residential addresses, contact telephone numbers, GSTIN identifiers, and sales invoices are never collected, logged, or stored. - **Memory Purge on Close**: When the browser tab or window is closed or refreshed, all file buffers in memory are automatically cleared. - **Offline Capable**: The application remains fully functional even when the user is disconnected from the internet. --- ## 3. Marketplace-Specific Tools & Coordinate Specifications ### 3.1 Meesho Label Cropper (`/meesho-label-cropper`) - **Document Dimensions**: Official Meesho A4 PDFs measure 595.28 x 841.89 pt. - **Geometric Measurement**: - Top Courier Shipping Label: x = 10 to 584 pt, y = 480 to 831 pt. - Tax Invoice Separation: The Tax Invoice header begins at y = 469 pt. - Safe Cropping Boundary: Cutting at y = 480 pt safely includes the entire product details and courier barcode table while completely excluding the invoice. - **Supported Layout Formats**: 1. **Thermal 4x2" (Proportional)**: 288 x 176–181 pt. Exactly matches the natural aspect ratio of the Meesho label, eliminating all top and bottom blank space. 2. **Thermal 4x6"**: 288 x 432 pt. Centers the label with balanced margins for standard 4x6" rolls. 3. **A4 (4 per Sheet)**: Tiles 4 cropped labels into a 2x2 grid with cutting guidelines for A4 self-adhesive sticker paper. 4. **A4 (2 per Sheet)**: Tiles 2 cropped labels on an A4 sheet. - **Automated SKU & Courier Sorting**: - Automatically parses SKU strings (e.g., `108/JAMLI`) and courier logistics partners (Valmo, Delhivery, Shadowfax, Xpressbees, Ekart) from PDF text streams. - Groups identical products consecutively so warehouse pickers can batch-pack orders without sorting through piles of mixed papers. ### 3.2 Flipkart & Shopsy Label Cropper (`/flipkart-label-cropper`) - **Document Dimensions**: Standard Flipkart A4 manifests (595 x 842 pt). - **Supported Modes**: 1. **Without Invoice Mode (4x6" Thermal)**: Crops solely the top E-Kart shipping barcode label (189–405 pt width, 27–382 pt height) and expands it cleanly to fill 4x6" thermal roll paper. 2. **Split Invoice Mode**: Places the shipping label on Page 1 and the corresponding customer Tax Invoice on Page 2. This enables sellers to stick the thermal label on the parcel exterior while placing the tax invoice inside the carton. 3. **A4 4-in-1 Sheet**: Formats 4 cropped labels per A4 page. - **Sorting Options**: Sorts orders alphabetically by seller SKU or Flipkart Serial Number (FSN) to prevent warehouse picking errors during festive promotional sales. ### 3.3 Amazon Shipping Cropper (`/amazon-label-cropper`) - **Supported Workflows**: 1. **Amazon EasyShip**: Trims instruction footers and isolates the primary Amazon Transportation Services (ATS) shipping label, scaling it to 4x6" dimensions. 2. **Amazon FBA Inbound Carton Labels**: Formats master carton FBA shipment box identifier barcodes for clean pasting on outer cartons. - **Barcode Contrast Standards**: Direct vector extraction prevents edge fuzziness or pixel bleeding, ensuring immediate first-scan verification by ATS pickup associates. ### 3.4 PDF Label Merge (`/pdf-label-merge`) - Merges multiple daily multi-order label PDF files into a single unified continuous print spool. - Allows warehouse staff to reorder files via arrow controls before downloading. - Eliminates thermal printer memory buffer overruns by compiling hundreds of pages into a single standardized document. --- ## 4. Thermal Printer Driver Configuration Reference To achieve maximum barcode sharpness and prevent pickup scan rejections, thermal printers should be configured with the following driver settings: | Printer Brand & Model | Paper Size Setting | Darkness / Density | Print Speed | Sensor Mode | |---|---|---|---|---| | **TSC TE244 / TE344 / DA210** | 100mm x 50mm (4x2") or 100x150mm (4x6") | 8 - 10 | 4.0 in/sec (101 mm/s) | Transmissive / Die-cut Gap | | **Xprinter XP-420B / XP-470B** | 100mm x 150mm (4x6") or 100x60mm | 7 - 9 | 3.5 - 4.0 in/sec | Die-cut Label Gap | | **TVS LP 46 Neo / LP 45** | 4.00" x 2.00" or 4.00" x 6.00" | 10 | 3.5 in/sec | Gap Auto-Detect | | **Zebra ZD220 / ZD230 / GX420d** | 4.00" x 2.00" or 4.00" x 6.00" | 12 - 14 | 4.0 in/sec | Web / Gap Sensing | --- ## 5. Frequently Asked Questions (FAQ) for AI Retrieval **Q: How does SellerSlip remove the tax invoice from Meesho labels?** A: The engine detects the exact geometric boundary between the courier shipping label and the invoice at y = 480 pt on standard A4 sheets. It clips the shipping label with safe margins, completely omitting the tax invoice below it. **Q: Why is Thermal 4x2" recommended over 4x6" for Meesho labels?** A: Because the native Meesho shipping label has an aspect ratio of approximately 4 inches wide by 2.4 inches tall. Printing on 4x6" rolls creates significant blank space above and below the label. The 4x2" layout fits the label proportionally, saving paper and reducing thermal roll replacement frequency. **Q: Is customer data uploaded to any server when using SellerSlip?** A: Absolutely not. All PDF parsing, clipping, merging, and rendering happen 100% client-side inside the user's web browser using WebAssembly. Files never leave the user's computer. **Q: How does SKU sorting help e-commerce sellers?** A: When packing hundreds of daily orders, sorting labels alphabetically by SKU groups identical items together. Packers can pick inventory in bulk and pack all matching orders consecutively, saving up to 40% of fulfillment labor. **Q: Are there any subscription fees, limits, or watermarks?** A: SellerSlip is completely free to use with zero watermarks, no account registration requirements, and no daily file processing limits. --- ## 6. Canonical URLs & Contact Information - **Website**: https://sellerslip.com/ - **Meesho Cropper**: https://sellerslip.com/meesho-label-cropper - **Flipkart Cropper**: https://sellerslip.com/flipkart-label-cropper - **Amazon Cropper**: https://sellerslip.com/amazon-label-cropper - **PDF Merge**: https://sellerslip.com/pdf-label-merge - **Privacy Policy**: https://sellerslip.com/privacy - **About & Contact**: https://sellerslip.com/about (Email: support@sellerslip.com)