Advanced Android Billing App

@sgrocean37

Hi, I already have experience with a similar billing solution covering invoices, payments, expenses and business management. I can adapt that experience to your requirements, including reliable accounting/CRM sync, cloud backup and complete source-code handover. Which accounting software and CRM are you using currently? Thanks, Sagar P.

@ixorawebmob

Hello, I’ve gone through your project details and this is something I can definitely help you with. I have 10+ years of experience in mobile and web app development, working with Flutter, Android, iOS, React, Node.js, and APIs. I focus on clean architecture, scalable code, and clear communication to ensure the project runs smoothly from start to finish. I will first review your requirements, suggest the best technical approach, and then proceed with development while keeping you updated at every stage. Here is my portfolio: https://www.freelancer.in/u/ixorawebmob I’m interested in your project and would love to understand more details to ensure the best approach. Could you clarify:Could you elaborate on the specific functionality you need for the CRM integration? 1. Do you need this for mobile, web, or both? 2. Do you already have UI/UX designs or should we create them? 3. Will there be any third-party API or payment gateway integration? 4. What is your expected timeline for completion? 5. Are there any reference apps or websites you like? Let’s discuss over chat! Regards, Arpit Jaiswal

@ciss26

Hi there, Hope you are doing well I’d be happy to develop your all-in-one Android billing and expense management application using Kotlin, with a strong focus on reliability, secure payments, offline capability, cloud backup, and accurate accounting/CRM synchronization. We have experience building billing/invoicing applications, payment integrations, expense management systems, CRM/ERP integrations, REST APIs, offline-first mobile apps, and business dashboards. Recommended Technology Android: Kotlin Architecture: MVVM + Clean Architecture UI: Jetpack Compose / Material Design Local Database: Room Backend/API: REST APIs Core Features Invoicing Create professional invoices Customer and product/service management Invoice numbering and status tracking PDF invoice generation/sharing Tax, discounts and totals Invoice history and search Payments Secure in-app payment processing Payment status tracking Receipts and transaction history Automatic invoice status updates Expense Management Add and categorize expenses Real-time expense tracking Attach receipts/documents Expense history and summaries Reporting-ready data structure

@Rajoriadares

Hello Client, Greeting of the day!!!! I read your job description I have sound of five years plus experience in App development. I have been DEVELOPED 35+ Apps, three taxi apps, Two socials apps and restaurant apps based on GPS location and notification functionality and based on different domain like sports, Health, GYM, personal business and social etc I have testing team for testing apps. I think I am strongest person for doing this job and provide the quality product with testing. I am always available for your support. Thanks Sr. Mobile Developer 

@tonybhsl

Hi, We have 17+ years of experience in mobile and software development, and can build your Android billing application with a clean, reliable architecture focused on invoicing, payments and real-time expense tracking. We can develop the app in Kotlin, following Material Design guidelines, with local data storage, automatic cloud backup and secure synchronization with your existing accounting software and CRM through APIs/REST integrations. The application will support Android API 24+, secure authentication/data handling, accurate data synchronization, error handling and complete API/integration documentation. Core delivery: Invoice creation & professional PDF generation In-app payment processing Expense tracking Accounting/CRM synchronization Offline/local data storage + cloud backup Modern responsive Android UI Testing across Android versions Complete Kotlin source code and documentation We can take this from architecture → UI → development → API integration → testing → APK delivery and provide full source-code ownership. Best regards, bivanshi

@mahads31

As an expert in API development and mobile app development, I'm perfectly positioned to create your Advanced Android Billing App. My name is Mahad Sheikh, and my team and I specialize in transforming complex ideas into tangible, scalable systems that drive long-term business growth. Not only can we build this app to work seamlessly on current Android versions down to API 24, but we'll also ensure it has a modern, intuitive UI that matches Material guidelines. Additionally, data security and accuracy are paramount, so rest assured that we'll employ the necessary measures to facilitate smooth data exchange with your existing accounting software and CRM. Moreover, given our proficiency in CMS, eCommerce, and CRM solutions, we'll be able to store your data locally with automatic cloud backup – providing you with ease of mind regarding storage and accessibility. Ultimately, my goal is to build technology that not only solves real-world problems but also grows with your business. With my extensive experience across various industries and international clients, moreover my consistent focus on reliable delivery; choosing me would mean choosing long-term success for your business. Let's turn your billing vision into a reality together!

@albertc1996

Hi, I can develop your Android billing application with a clean Material-based UI and a reliable architecture that supports billing, payments, expenses and external system integrations. I can handle: • Professional invoice creation and management • In-app customer payment processing • Real-time expense tracking • Local data storage with automatic cloud backup • Secure REST API integrations • Synchronization with your accounting software and CRM • Customer, invoice and payment status synchronization • Android API 24+ compatibility • Error handling and data validation • Complete testing of the core workflows • Full Kotlin source code • API and integration documentation I would recommend Kotlin for the Android application because it provides a modern, maintainable and reliable foundation for long-term development. I’ll make sure the application is tested end-to-end, including sample data synchronization with your accounting and CRM systems. Fixed Price: ₹32,000 INR Estimated Timeline: 14–18 days I’m available to start immediately and can provide regular progress updates throughout development. Best regards,

@aptechzain1

Hi! I can build your Android billing app in Kotlin with clean API development for accounting and CRM sync, plus secure local storage and Material UI. Do you already have the accounting and CRM API details, or should I build the connectors from scratch? I can share the APK, source, and endpoint docs. Portfolio:

@bilal4240

I will build your all-in-one Android billing application in native Kotlin, integrating full invoice generation, secure in-app payment processing (Stripe/Square SDKs), and real-time expense tracking with an offline-first Room database and automated cloud backup. I will also construct a clean REST integration layer to sync invoices and customer records with your accounting software and CRM, delivering a fully documented, Material 3-compliant APK targeting API 24+. Regards, Bilal

@ammarahmed20

As an accomplished developer with a proven track record of building complex systems and applications, I believe I'm the ideal person for your Advanced Android Billing App project. Over the past 6+ years, I've successfully crafted AI-powered systems, full-stack platforms, and mobile apps that seamlessly run in production. My expertise in API development and mobile app development would significantly contribute to your app's smooth data exchange with existing accounting software and CRM. I understand the importance of running your app on multiple Android versions and data safety. Having worked with healthcare, real estate, e-commerce, and SaaS companies, I'm well-versed in ensuring applications are backward-compatible and incorporate automatic cloud backup. Additionally, I pride myself on delivering modern, intuitive UIs that align with Material guidelines. In addition to my technical proficiency, I offer you a dedication to end-to-end project management. With me as your partner, you can expect not only clean code but also extensive documentation to facilitate maintenance and future updates. Allow me to help transform your billing process into a seamlessly integrated system that boosts efficiency for your small business.

@Zaiyan

I can build your Android billing app to generate invoices, process payments, and track expenses in real-time. My first step will be to outline the core features and ensure that the app integrates smoothly with your existing accounting software and CRM. Based in Toronto, Canada, I work efficiently and will keep you updated throughout the process. Let's create a robust solution together.

@YousefAiman

Hi, I’d approach this as three clean modules rather than building the entire billing workflow as one tightly coupled system. I can build the Android app natively in Kotlin with MVVM, Room for reliable local storage, Retrofit for REST integrations, and a Material-based UI. I’d first complete invoicing and local customer/billing data, then add expense/payment handling, and finally connect the accounting/CRM systems and cloud backup. This keeps each stage testable before moving to the next. I’ll also handle offline/online synchronization carefully so invoices or payment states aren’t duplicated when connectivity changes, and keep the integration layer separated so APIs can be maintained later. Before starting, I’d just need to know which accounting software, CRM, and payment provider you currently use, since those integrations will determine the exact implementation effort. I can target around 12 days including testing, API documentation, source code and final APK/AAB. Best, Yousef

@adityakhuman006

As a seasoned app developer and skilled in Java, your project on Advanced Android Billing aligns perfectly with my repertoire. Given the essence of professional billing, I understand the significance of having a smooth, intuitive, and secure application that can generate invoices, process payments, and efficiently track expenses - all while staying in sync with your existing tools. My deep proficiency in Android App Development ensures that the final APK I deliver installs flawlessly across Android versions down to API 24. Moreover, my knack for clean coding will empower your app to store data locally with automatic cloud backup - ensuring your users never lose important information. Being a proponent of well-structured UI design that adheres to Material guidelines, you can rest assured knowing the final product will exude modernity and intuitiveness while not compromising on functionality. And when it comes to documentation, I am always meticulous in offering clear directions for every endpoint and integration point. Considering my successful history and vast experience as a freelancer, I promise uncompromised dedication to exceed your expectations. With me on board, not only will your APK be crash-free and functional but also smoothly integrate the necessary APIs for your accounting software and CRM. Let's make this small-business billing dream come true together!

@TechWagger2026

As a seasoned Full-Stack Developer with a specialization in Mobile App Development, I have extensive experience in Android platform and proficient in both Java and Kotlin. I’ve successfully executed over 416 projects with diverse features – exactly what you need for your Advanced Android Billing App project. My priority is to create intuitive, stable, and functional apps without glitches - a guarantee for running cleanly on all current Android versions down to API 24. Beyond technical expertise, what sets me apart is my customer-centric approach. I consistently dedicated myself to delivering tailored IT solutions that fit each client’s unique needs, which is precisely the kind of service you deserve for your holistic billing app. Prompt communication, transparent documentation of every endpoint and integration point combined with my determination toward client satisfaction will provide you the seamless collaboration you seek. Let's transform your billing process into an efficient powerhouse!

@krupaHingrajia

Hi, I’m a Flutter developer with 5+ years of experience building production-ready mobile apps with complex business workflows and API integrations. This project is a strong match for my experience with SKS Trader, where I worked on product, order, business, notification, and multi-role workflows, as well as VG Advantage, involving structured booking, user, and backend-driven workflows. I’ve also worked extensively with REST APIs, Firebase, local databases, authentication, cloud services, data synchronization, and admin/business applications. I focus on reliable data handling and making sure frontend and backend data remain consistent across different workflows. For your app, I can build a clean Material-based interface with proper local data handling, secure API communication, cloud backup/sync, and well-structured integration points. I can also provide clear documentation so the accounting and CRM integrations are easy to maintain. I can share relevant previous work and discuss your existing accounting/CRM systems before development.

@thiagofoz87

Your project requires more than a basic Android app because invoice generation, payment processing, expense tracking, and third-party synchronization all need to work reliably together without data inconsistencies. The most important part is designing a stable integration layer so accounting and CRM records remain synchronized even with intermittent connectivity or failed requests. I would approach this using Kotlin with a clean modular architecture, Room for local persistence, encrypted local storage where necessary, and a secure REST integration layer for accounting/CRM synchronization. For cloud backup and sync reliability, I can implement scheduled background synchronization with retry handling and conflict protection to avoid duplicate invoices or payment mismatches. The application would target API 24+ and follow current Material Design guidelines with a responsive and intuitive UI focused on fast billing workflows. I can also structure the codebase to keep integrations isolated, making future connector additions easier. The delivery would include: - Android source code in Kotlin - Signed APK build - Invoice, payment, and expense modules working end-to-end - REST integration layer with authentication handling - Documentation for APIs, payloads, and synchronization flow - Basic testing and crash validation on supported Android versions Given the requested scope, I recommend starting with a well-defined MVP covering the complete billing flow and one accounting/CRM integration, then expanding additional integrations if necessary.

@shayankhan333

Hello, I will build your Android billing app in Kotlin with invoicing, in-app payments, and expense tracking in one module, plus REST sync to your accounting software and CRM. Local storage with cloud backup and Material UI, targeting API 24 and up. I can start today. For the CRM and accounting sync, I will add a retry queue so invoices and payment statuses stay accurate even when the phone briefly loses signal. Questions: 1) Which accounting software and CRM do you use? 2) Preferred payment gateway? Looking forward to discussing further. Regards, Shayan.

@aakaashberi

Straight answer on the two things that decide this build: In-app payments: I won't build a card processor — I integrate a proven SDK (Razorpay or Stripe) so card data never touches your app and PCI stays with them. Safe path, not a custom payment screen. The accounting/CRM sync is where the real scope hides. "Perfectly in sync" depends entirely on WHICH tools — Tally, Zoho, QuickBooks each have different APIs, and some have no clean one. A REST bridge works, but I need the exact accounting software + CRM names before I promise the sync. That honesty saves us both a nasty mid-build surprise. One thing your brief misses but a billing app needs: offline-first. Users will invoice with no signal. So local SQLite/Room is the source of truth, with a sync queue that pushes to cloud + your tools when back online — not an app that breaks the moment WiFi drops. Kotlin, Material UI, API 24+, local storage + auto cloud backup, full source + endpoint docs — as specified. ₹12,500 = Phase 1: the core app — invoices, expenses, in-app payments — end-to-end with local storage + backup. Phase 2 wires the accounting/CRM sync once I have the exact tool names. Two questions: Which accounting software and which CRM, exactly? Which payment provider do you use or want?

@webphp0321

Hi, I can build your all-in-one Android billing application with a clean Material UI, reliable local storage, cloud backup, and secure integrations with your existing accounting and CRM systems. I have experience with native Android development using React REST APIs, payment integration, database architecture, cloud synchronization, and third-party integrations. I’ll ensure invoices, customer records, expenses, and payment statuses remain accurately synchronized across platforms. Key Deliverables Professional invoice creation & PDF generation Secure in-app customer payments Real-time expense tracking Local database with automatic cloud backup Accounting software & CRM integration via API/connectors Secure REST API implementation where required Android API 24+ compatibility Modern Material Design UI Complete Kotlin/Java source code API & integration documentation Testing with realistic sample data Production-ready APK I’ll focus on data accuracy, security, performance, offline reliability, and easy future maintenance. I can first review your accounting/CRM APIs and confirm the best integration approach, timeline, and cost before development begins. Regards, ALOP