// Mobile app · Full handover
Mr Invoice GST Bill Maker
A free GST billing, invoicing and inventory app, live on the App Store and Google Play, sold as a complete handover: source code, both store listings, backend and admin panel.
// 01 · 39 real screenshots
See the actual app, before you enquire.
// 02 · 106 features across 21 modules
Every feature, module by module.
Onboarding
Navigation and Flow Control
A four-slide welcome tour lets users step through the app's highlights or skip straight to setup, with no loss of progress.
Legal Consent
Continuing past the welcome tour counts as agreeing to the Terms and Privacy Policy, viewable in-app without a separate checkbox.
Slide Layout and Animation
Each onboarding slide uses a consistent layout with smooth entrance animations every time it appears, keeping the intro visually polished throughout.
Tablet and Responsive Design
The welcome tour adapts its layout for tablets and phones and works fully offline, needing no network access, permissions, or ads.
Initial Setup
Setup Wizard Navigation
A three-step wizard handles country, currency and language selection (English only at launch), works offline, and needs no extra permissions or ads.
Authentication
Sign-In and Sign-Up Flow
Sign-in, sign-up and password reset all flow together smoothly, with back navigation handled safely so users never accidentally exit mid-process.
Sign In
Users sign in with email and password; validation runs before submitting, and generic error messages never reveal whether an email is registered.
Sign Up
New users sign up with basic details and a simple password rule, then land signed in, no email or OTP step needed.
Forgot Password
Resetting a forgotten password uses an emailed code, a spam-limiting cooldown, and privacy-safe messaging, then signs the user back in automatically.
OTP Code Entry
Verification codes are entered through an easy six-digit input that auto-advances between boxes and supports pasting the whole code at once.
Country and Dial Code Picker
A searchable country and dial code picker, with common markets pinned to the top, helps during sign-up; sign-in requires an internet connection.
Business Setup
Business Setup Flow
First-time setup walks new business owners through a short six-step flow covering business name, branding, address, tax details and invoice preferences.
Business Name and Type
Users enter their business name and pick a category (retail, wholesale, service, freelancer, or other) to tailor the app to their business.
Camera and Photo Permissions
Before asking for camera or photo access, the app explains why it's needed; users can allow or skip, and setup continues regardless.
Business Logo
Users can upload a business logo or skip it for an auto-generated initial letter, and can remove or change it anytime.
Digital Signature
Users can draw or upload a signature, which is fully optional and gets reused automatically as the Authorised Signatory on invoice templates.
Business Address
Business address fields are optional, with labels that automatically adapt to local conventions, such as State and PIN code in India.
Tax Registration
Tax registration is optional, with the field label automatically matching the country, such as GSTIN in India or ABN in Australia.
Invoice Numbering and Terms
Invoice numbering and default payment terms are fully customizable, with a live preview and business data kept safely in sync across devices.
Bootstrap / App Launch Gate
App Launch Screen
A short branded splash screen plays on launch while the app checks your connection and login status, extending briefly if needed.
Update & Connectivity Checks
Checks for required or optional updates and maintenance status at launch, and shows a clear offline screen that blocks actions until you're reconnected.
App Permissions
Asks for optional storage and camera access during setup, but you can continue using the app regardless of whether you grant them.
Home / App Shell
Main App Navigation
Five sections, home, invoices, parties, reports, and stock, with a layout that adapts between phone and tablet, and no ads on tab switches.
Quick Actions
One-tap shortcuts to create a new invoice, expense, or party, or scan a barcode, with the screen refreshing automatically to show it.
Home Dashboard
Dashboard shows a revenue chart, key totals, low-stock warnings, and recent activity, with honest empty states instead of fake numbers.
Search & Notifications
Instantly search invoices, parties, and products by name, and view notifications with unread badges that stay in sync when marked as read.
Multi-Business & Cloud Sync
Switch between multiple businesses in one app, with each one automatically linked to your account online while still working fully offline.
Invoices & Billing Documents
Create Billing Documents
Create invoices, quotations, purchase orders, credit/debit notes, and more, with automatic numbering, smart due dates, and a warning before losing unsaved edits.
Line Item Editor
Add line items with quantity, price, discount, and tax; entered amounts are validated, and GST splits into CGST/SGST or IGST by state.
Template Unlocking
Premium invoice designs unlock temporarily after watching ads; drafts always save for free, and ads can be turned off app-wide by the owner.
Sharing & PDF Export
Share invoices via WhatsApp, SMS, or email with a viewable link, generate and print PDFs, and format numbers to match the invoice's currency.
Payments & Conversion
Record payments by multiple methods, convert quotations and challans into invoices, and manage documents with filters, bulk actions, and safe-delete warnings.
Import & Export
Import invoices from a CSV file, and export your invoice list to CSV or a bundle of PDFs across custom date ranges.
Automatic Stock Updates
Saving a sales invoice automatically reduces stock on hand for tracked products, without double-counting when you edit an invoice later.
Templates
Template Gallery
Browse 40 invoice designs across many industries, searchable and organized by category, with every design unlocked by watching a short ad.
Template Customization
Customize a template's color, font, and logo for built-in designs, though only color changes carry through to the final printed invoice.
Preview & Rendering Notes
Explains that a preview must be applied when creating an invoice, and clarifies whether the design renders on your device or the server.
Parties
List, Search and Filtering
Browse customers and suppliers in tabs, search by name or contact details, filter and sort by balance, tags, or favourites.
Add or Edit a Party
Add or edit customers and suppliers with contact details, country-specific tax ID formats, billing and shipping addresses, and credit terms.
Party Detail View
View a party's contact, tax, and address details, lifetime stats, and quick actions like call, WhatsApp, or send reminders.
Delete a Party
Deleting a party warns about any outstanding invoices, payments, or balance, and requires confirmation before removing it from the list.
Statement PDF Export
Generate a statement PDF for a chosen date range showing opening and closing balance, debits and credits, ready to share or download.
Payment Reminders
Send a payment reminder to a customer via WhatsApp, SMS, or email, choosing a gentle, firm, or overdue tone.
CSV Import
Import customers and suppliers in bulk from a CSV file, matching columns to fields and previewing entries before saving, fully offline.
Inventory & Stock
Product Catalogue
Create and manage products with auto-generated barcodes and SKUs, pricing, tax rates, and stock levels, with search, filters, and sorting.
Low Stock Alerts
Automatically flags products that are low or out of stock using per-product or account-wide thresholds, with a quick option to adjust stock.
Stock Movements
Track stock in, out, transfers, adjustments, and wastage across warehouses, with automatic deduction on sales and a full movement audit log.
Batches, Serials, and Expiry
Track inventory by batch with expiry dates, see upcoming and expired lots at a glance, and track individual items by serial number.
Barcode Scanning
Scan a product's barcode or QR code with the camera to find it in the catalogue or add it as new.
CSV Import
Import or update products in bulk from a CSV file using a template, matching by SKU and previewing results before saving.
Bulk Price Update
Update sale, cost, or MRP prices across many products at once, by percentage, flat amount, or a fixed replacement value.
Warehouses, Categories, and Units
Organize products into categories with icons, manage multiple warehouse locations, and define units of measure, all working fully offline.
Point of Sale
Counter and Shift Management
Select a sales counter, track today's sales and cash in the till, and close out a shift with a printable reconciliation report.
POS Catalogue and Cart
Browse products as tiles with live stock, search by name or barcode, build a cart, and park a bill to recall later.
Discounts and Coupons
Apply a percentage or flat discount, or a coupon code, to a sale; manager-override discounts are not yet available.
Barcode Scanning
Scan a product barcode at checkout to add it straight to the cart, using the device camera.
Payment Collection
Accept cash, UPI, card, or split payments, calculate change automatically, and save the sale as an invoice, even for walk-in customers.
Receipt Printing and Sharing
Print or share a receipt by WhatsApp, SMS, or the system share sheet, formatted for common receipt roll sizes.
Z-Report Summary
Get an end-of-shift summary of sales, tax collected, discounts, payment methods, and top products, with a cash count for reconciliation.
Payments & Receivables
Recording a Payment
Record incoming or outgoing payments, link them to a customer's invoice, and the invoice's paid status updates automatically.
Payment Lists and Detail
Search and review payment history, and delete entries with confirmation; deleting a payment doesn't adjust the related invoice's balance.
Bank Accounts
Track cash, bank, UPI and wallet accounts with running balances, generate UPI payment QR codes, and export account statements as CSV.
Cash Register
View today's cash position with a running opening balance and movements; this is a read-only snapshot, not a closing or reconciliation tool.
Outstanding Invoices
See all unpaid invoices grouped by due-soon or overdue status, with color-coded day counts, and open any invoice's detail with a tap.
Receivables Dashboard
View outstanding receivables broken into ageing buckets (current through 90+ days) and see your top six parties by amount owed.
Payables Dashboard
Track amounts owed to vendors from their opening balances; without purchase-order support yet, everything shows as currently due rather than aged.
Bulk Reminders
Send payment reminders to unpaid customers via WhatsApp, SMS or email with tone and language templates, sending one recipient at a time.
Reminder Template Editor
Customize reminder message text for each channel, tone and language combination, with only a few starter templates provided out of the box.
Expenses
Recording an Expense
Log an expense with amount, tax, category, payment mode and status, and see the tax-inclusive total calculated automatically as you type.
Expense Receipts
Attach a photo or document as a receipt for each expense, then filter and sort expenses by status, category or receipt presence.
Bulk Selection and Actions
Select multiple expenses at once to see a running total and delete them together with a confirmation step.
Expense Quick Actions
From an expense's detail screen, mark it paid, duplicate it, or attach a receipt; sharing and PDF export aren't available.
Expense Categories
Organize expenses into categories with live counts and monthly totals; built-in categories are read-only, while custom ones can be edited or deleted.
Known Limitations
Expense amounts always display in rupees, and the outstanding total on the expense list may not match the dashboard's total.
Tax & GST Compliance
Jurisdiction Routing
Shows the right GST, VAT or sales-tax reports and rates for your business's country, computed automatically from invoices and expenses you've recorded.
Honesty Guardrails
Screens with sample figures are clearly labeled, and actions like filing directly to tax portals are shown as unavailable rather than faked.
Tablet Layout
Tax report screens use a wider, multi-column layout on tablets for easier reading.
Reports & Analytics
Report Catalogue
Access 18 ready-made reports organized under Sales, Purchase, Financials, Stock, Party and Expenses, with a few additional reports still coming soon.
Date Range Filters
Choose from nine preset date ranges or a custom range for most reports; stock and similar point-in-time reports always show current data.
Report Filters
Filter reports by draft/cancelled status and amount range; party, item, category and warehouse filters are shown but not yet selectable.
Report Calculations
Automatically calculates sales, purchase, profit and loss, cash flow, stock valuation, party ledgers, aging and expense figures from your business data.
Export, Print & Share
Export reports to CSV or PDF, and share via Print or any installed app; no direct WhatsApp, SMS or email sharing yet.
Visual Report Design
Reports are presented with animated summary cards, bar, donut and stacked charts, progress bars and haptic feedback for quick, at-a-glance reading.
Settings
Settings Search & Overview
Search settings to jump to any screen, with a layout that adapts for phone or tablet and shows tax and notification status.
Manage Businesses
Create, edit, switch between and delete multiple businesses, each with its own logo, tax ID label and currency, synced with the server.
Invoice Preferences
Customize invoice numbering, footer notes, terms, due-date defaults, signature and low-stock auto-deduct settings, though some numbering-format options are preview-only for now.
Country & Currency
Set your business country and currency, plus additional secondary currencies, chosen from built-in lists that work even offline.
Tax Settings
Choose GST, VAT, Sales Tax or a custom mode, each with a matching tax ID label and an editable tax rate list.
Printer & Scanner
Print receipts and product labels, including barcodes, on a connected USB thermal printer, and scan barcodes using the phone's camera.
App Lock & Security
Protect the app with a PIN and optional biometric unlock, and see a security score, though two-factor authentication is not yet available.
Active Sessions & Backup Key
View active login sessions and sign other devices out in bulk, and manage a masked backup recovery key to restore encrypted backups.
Delete Account & Export
Log out, permanently delete your account and data with a typed confirmation, or export your data as a JSON backup file.
Help & Support
Browse FAQs, rate their helpfulness, submit and reply to support tickets, and contact support directly or via WhatsApp.
Cloud Backup & Restore
Cloud Backup and Restore
Backs up all business records to the cloud and lets you restore them later, merging with local data without deleting local-only entries.
Legal, About and Open Source Licenses
About and Legal Pages
Gives users easy access to About, Terms & Conditions and Privacy Policy from settings or before sign-in, with data-rights and ad-consent options.
Open Source Licenses
Lets users browse and search the open-source licenses of third-party packages used in the app, viewable offline.
Grow With Us
Agency Promo Card
Displays a promotional card on the dashboard advertising the app developer's own agency services, which opens a dedicated screen when tapped.
Agency Services Detail Screen
Displays a full list of the developer's agency services with descriptions, and two buttons that open the developer's website in the browser.
External Website Links
Opens each service link to the developer's website in the device browser, failing silently with no error message if it cannot open.
Tablet Layout
On tablets, the promotional screen's content is width-capped and centered with wider margins instead of stretching across the full screen.
Recovery / Edge-Case Screens
Session Expired Screen
Automatically shown when a saved sign-in session expires, prompting the user to sign in again with their remembered email pre-filled where available.
Server Error Screen
Shown when the app's startup check hits a server error (not a network problem), displaying an error code and a retry button.
Account Deletion Confirmation
Confirms the account has been permanently deleted with no restore option, then lets the user sign in or create a new account.
Recovery Screens Copy Notes
These recovery screens are plain informational text with no ads, permissions or network features; one status link points to a separate domain.
Shared UI Toolkit and Utilities Gallery
Shared UI Component Library
A shared library of reusable interface pieces, toasts, dialogs, pickers, empty states and loading skeletons used throughout the app.
Payment QR Code Screen
Generates a scannable UPI QR code for receiving payments, with options to copy, share or save it as an image.
// 03 · Technical specification
The stack, line by line.
// 04 · What transfers to you
A full handover, not just a zip file.
Flutter mobile app source
The complete shipping product: 513 Dart files, 157 screen files across 21 feature modules, roughly 213,000 lines of Dart.
NestJS backend API source
291 TypeScript files across 44 feature modules, including auth, invoices, invoice templates, PDF rendering, backup, ads and notifications, with the complete Prisma schema.
Next.js super admin panel source
93 files. The full internal operations console: analytics, user management, business management and template catalogue control.
Live App Store listing
App Store ID 6784823439, bundle com.fouram.mrinvoice, version 1.0.2 build 12 currently live, with the iOS release configuration.
Live Google Play listing
Play ID 4972524484049476117, applicationId com.fouram.mrinvoice, versionCode 12, with the Android release configuration and signing setup.
The 501-template invoice catalogue
1,002 files: 501 self-contained HTML templates paired with 501 JSON metadata sidecars, across 31 industry categories.
Backend infrastructure and deploy tooling
The deploy scripts, nginx configuration and the running production stack topology.
Monetization wiring
The full AdMob integration, transferable to the buyer's own ad accounts without an app update, since ad unit IDs are server-controlled.
Domain and business logic
The money engine: tax calculation, GST splitting, rounding rules, invoice numbering, stock deduction and report computations.
Test suites and QA harness
25 Dart test files, backend Jest specs, and the device QA harness used to verify the app before each release.
The complete documentation
The 270-page product and technical documentation this page is built from, written by reading the source tree file by file.
The git repository
A single repository holding all three codebases, with full local history intact.
// Ready to talk?
Interested in acquiring Mr Invoice?
Full source code, live store listings, backend and admin panel, in one handover. Message us on WhatsApp and we will walk you through it.