Invoice Studio - Offline Android Invoice & Estimate App Source Code

Good work deserves clear paperwork

A working Android Studio project for an invoice and estimate app. Create itemized documents, reuse client details, set a business profile and export multi-page PDFs. The application works locally without an account or seller-operated backend.

The gallery shows actual application screens with clearly fictional sample business and client data. The sample workspace is optional; a normal fresh installation starts empty.

Included features

• Invoices and estimates with automatically allocated document numbers.
• Reusable client directory and business/payment details.
• Quantity and unit-price line items; percentage discount before tax.
• Two-decimal HALF_UP monetary rounding.
• USD, EUR, GBP, RUB, CAD and AUD documents; no mixed-currency dashboard sums.
• Draft, sent, paid, accepted and overdue document states, as appropriate.
• Convert an estimate into a new invoice; duplicate a document as a new draft.
• Multi-page PDF generation, system PDF save and temporary read-only sharing.
• Validated JSON backup and atomic restore, including numbering counters.
• English interface, Kotlin, Jetpack Compose, Room and lifecycle-aware ViewModels.

What you receive

Full Android Studio source project, Gradle wrapper, evaluation APK, example PDF, English build/customization guide, tests, Room schema, project source license and third-party notices. No private signing keys or seller accounts are included.

Requirements

Android 8.0+ (API 26), JDK 21 and Android SDK Platform 37. AGP 9.4.1, Kotlin 2.4.10 and Gradle 9.7.1 are pinned in the project. Initial dependency download requires internet. Android development experience is expected. Release output requires your own signing and store setup.

Non-exclusive license

Single Licence: one branded Android end product. Multiple Licence: unlimited branded Android end products for the buyer or their clients. Compiled end products can be distributed commercially. The project-owned source/template cannot be resold or publicly redistributed. Third-party rights and notices remain applicable. Replace the demo name, icon and app ID before publishing your own product. Ownership and exclusive rights are not transferred.

Scope and support

This is a manual invoice/estimate tool. It does not include a fiscal cash register, certified tax rules, government e-invoicing integration, payment collection, bank reconciliation, partial-payment accounting, cloud synchronization, dark mode, translations, ads or billing integration. Users enter their own tax rates and business information. Additional database encryption is not included. Revenue and app-store approval are not guaranteed.

Use the marketplace purchase channel for basic setup questions and reproducible defects. Custom development, hosting, store submissions and future OS migrations are outside the supplied package.