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I already run my business on a desktop-based invoicing tool and can supply its full source code. I want an exact replica built from that code, retaining the entire workflow and interface, but I also need a seamless WhatsApp integration so I can share invoices or payment reminders directly from the app. The new build must run reliably on Windows, match every existing screen and function, and keep all current features—client management, payment tracking, and automated recurring invoices—intact. While you are free to refactor or modernise the codebase for maintainability, the user experience should feel identical to what I have today. Key deliverables: • Compiled Windows installer and signed executable • Complete, well-commented source code • Fully functional WhatsApp messaging module (using official API or approved SDK) tied into the invoice send and reminder flows • Brief setup & user guide so I can deploy future updates in-house I’ll provide the original project files, database schema, and a short video walkthrough as soon as we begin. Let me know your preferred tech stack, any clarifications you need, and a realistic timeline for a like-for-like rebuild plus the new messaging layer.
Project ID: 40513188
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Having the source code already changes everything. I will review it, rebuild the core in PHP, and wire in WhatsApp via the Cloud API for sending invoices straight from the app. That cuts the rebuild time a lot. Can start today and have a working version ready in 4 days. Pricing shown reflects the post as written. Once I review the code, the real scope may turn out larger. Want me to send a quick scope doc?
$150 USD in 10 days
2.4
2.4
110 freelancers are bidding on average $136 USD for this job

Hello, Leveraging my decade-long experience as the head of a reputable global software company, I am confident our team at Yasir's Software are the perfect fit for your project. As web service providers, we excel in turning clients' specific needs into a reality using the latest technologies. We understand that you're seeking a like-for-like replication of your existing desktop invoice tool with a seamless WhatsApp integration, and we're up for this challenge. By utilizing my broad proficiency in C# programming alongside my team's robust knowledge of PHP and Software Development, we will ensure that every component of your present system seamlessly integrates with the newly added messaging functionality. Apart from matching the existing screens and features identically, we also appreciate the need to modernize codebases while preserving their functionality. Our team will refactor your tool making it future-proof, easier to maintain and up-to-date using industry-best practices. Not only can we guarantee you a reliable Windows installer, complete source code and functional WhatsApp messaging module but also provide detailed instructions for you to self-manage future updates - freeing your business from dependency on external developers. When you select our team at Yasir's Software for this project, you'll benefit from our commitment to the "WOW" factor in all our projects; resulting in a transformative solution that will elevate the Thanks!
$130 USD in 2 days
8.6
8.6

⭐⭐⭐⭐⭐ Build a Reliable Invoicing Tool with WhatsApp Integration ❇️ Hi My Friend, I hope you are doing well. I've reviewed your project requirements and see you are looking for an exact replica of your desktop-based invoicing tool. Look no further; Zohaib is here to help you! My team has completed 50+ similar projects for invoicing systems. I will ensure that the new build runs smoothly on Windows and retains all current features while adding seamless WhatsApp integration. ➡️ Why Me? I can easily create your invoicing tool with WhatsApp integration, as I have 5 years of experience in software development, focusing on desktop applications, client management, and payment tracking. My expertise includes building user-friendly interfaces and integrating messaging functionalities. Additionally, I have a strong grip on modernizing codebases for better maintainability. ➡️ Let's have a quick chat to discuss your project in detail and let me show you samples of my previous work. I look forward to discussing this with you in our chat. ➡️ Skills & Experience: ✅ Windows Application Development ✅ Invoicing Systems ✅ Client Management ✅ Payment Tracking ✅ API Integration ✅ WhatsApp Messaging Integration ✅ User Interface Design ✅ Database Management ✅ Code Refactoring ✅ Software Maintenance ✅ Documentation Writing ✅ Agile Development Waiting for your response! Best Regards, Zohaib
$150 USD in 2 days
8.0
8.0

Hello, I understand you need an exact replica of your existing Windows invoicing application while preserving all current workflows, screens, client management, payment tracking, and recurring invoice functionality, with the addition of WhatsApp integration for invoice delivery and payment reminders. I can help review the existing source code, modernize and refactor where beneficial, and deliver a Windows application that maintains the same user experience while adding a reliable WhatsApp messaging module using an official API or approved integration approach. With 6+ years of experience in C#/.NET desktop development, I have built invoicing systems, CRM applications, business management platforms, and workflow automation solutions. I understand the importance of maintaining business continuity while enhancing functionality and long-term maintainability. Deliverables will include the Windows installer, complete source code, WhatsApp integration, deployment documentation, and user guide. Once I review the existing codebase, database structure, and walkthrough video, I can provide a detailed timeline and implementation plan. Regards, Muhammad Shoaib
$150 USD in 7 days
6.8
6.8

With over 13 years in the field, my broad range of skills and experiences make me a standout choice to undertake your invoice cloning project. As a seasoned developer in both Python and C# programming, I am poised to replicate your desktop invoicing tool, preserving all its current features whilst integrating a WhatsApp interface for seamless communication. One of my notable projects which aligns closely with yours is the AI emergency caller using Vapi and Twilio. Here, precision and reliability were crucial elements just like your request for an exact replica retaining the entire workflow. Alongside this completed project, I have developed several software applications including AI bots install on both MacOS and Windows operating systems. Considering your preferred tech stack, my proficiency in Python, C# programming combined with experience using tools like Selenium, BeautifulSoup makes me a great fit. To ensure you can comfortably handle the system going forward; setup & user guide would be provided plus well-commented source code to facilitate easier future updates and maintenance in-house. Choose me today to not only bring a deep level of expertise but also collaborative spirit to your project. Reach out to me now to schedule a further discussion on the specifics of this like-for-like rebuild plus the new messaging layer. I am more than ready to turn this into reality for you!
$40 USD in 1 day
7.0
7.0

Hi There!!! ★★★★ ( Exact Desktop Invoice Clone + WhatsApp Integration ) ★★★★ Project understanding: I understand you need an exact replica of your existing desktop invoicing system using provided source code, keeping same workflow, UI and features like client management, payments tracking and recurring invoices. Along with this, you want WhatsApp integration to send invoices and reminders directly, plus Windows installer and full source code. ⚜ Exact desktop clone with same UI & workflow ⚜ WhatsApp API integration for invoices & reminders ⚜ Windows installer + signed executable build ⚜ Client, payment & recurring invoice modules intact ⚜ Code refactoring for better maintainability if needed ⚜ Database setup with existing schema support ⚜ Full source code + documentation for future updates I have strong experiance in C#, .NET and desktop based business apps, also worked on API integrations like messaging and automation systems. I focus on stable architecture and clean code so client can manage updates easily. I will use .NET (or your existing stack PHP/C# based on code), integrate official WhatsApp Cloud API, and carefully match your current system so user experiance remains identical. Testing will be done on full invoice flow before delivery. Happy to discuss timeline and start right away. Warm Regards, Farhin B.
$118 USD in 7 days
6.6
6.6

Drawing from my wealth of experience as a full-stack developer, I am skilled in developing desktop applications, especially PHP-based ones similar to your project. I'll ensure a smooth transition and replicate every existing screen and function, guaranteeing that client management, payment tracking, and automated recurring invoices remain intact. My vast knowledge in AI engineering also complements the WhatsApp integration aspect of this project. Beyond the mere reconstruction of your current tool, I'll refactor and modernize the codebase for easy maintainability while masterfully preserving the user experience you value highly. I'm well-versed in LLM-powered applications using LangChain, LangGraph, and RAG pipelines with vector databases (ChromaDB, pgvector), making me a good fit for building an AI-driven system that can connect to external tools through MCP like you've requested. Choosing me means more than just getting the project done on time; it means having someone who understands your needs and is committed to seeing your vision come to life. My track record in full development services including custom SaaS platforms, automation backend, API integrations align perfectly with your project requirements. Let's turn your concept into a fully functional high-performance product while keeping security at the forefront. With me on your team, you'll never experience ghosting or overpromising because my job isn't done until you're fully satisfied.
$175 USD in 2 days
6.1
6.1

Hi there, I will rebuild your Windows desktop invoice app from your supplied C#/.NET source to produce an exact UI/workflow clone and add a WhatsApp messaging module using the official WhatsApp Business API or approved SDK so invoices and reminders send directly from the app. - Compiled Windows installer (signed .exe) and full installer script matching current screens and workflow - Complete, refactored and well-commented source code (C#/.NET), database migration scripts, and deployment notes - Fully functional WhatsApp messaging module integrated into invoice send and recurring reminder flows (official API or SDK, OAuth/keys configured) - backup checkpoint and post-deploy validation to ensure feature parity and minimal downtime Skills: ✅ C#/.NET ✅ Windows desktop (WinForms/WPF) environment ✅ WhatsApp Business API integration ✅ Database migration & deployment scripting ✅ Installer signing & Windows deployment Certificates: ✅ Microsoft® Certified: MCSA | MCSE | MCT ✅ cPanel® & WHM Certified CWSA-2 I’m available to start immediately. Should I implement WhatsApp via the official Business API (requires business verification) or use an approved SDK/provider for faster setup? Best regards,
$230 USD in 1 day
5.9
5.9

I have read your job post and I would love to help rebuild and enhance your invoicing application. I am a Full Stack Software Developer with experience in Windows desktop applications, business management systems, invoicing software, database migrations, and WhatsApp API integrations. I have worked on projects involving legacy software modernization, desktop application redevelopment, payment tracking systems, recurring billing workflows, and business process automation. My approach is to first review the existing source code, database schema, and workflow documentation to ensure the new application preserves the exact functionality and user experience your team already relies on. The solution will include a like-for-like rebuild of the invoicing system, client management, payment tracking, recurring invoice automation, and seamless WhatsApp integration for invoice sharing and payment reminders using approved WhatsApp Business APIs. I will provide a Windows installer, complete source code, documentation, deployment guidance, and a maintainable architecture that supports future enhancements while keeping the application familiar to existing users.
$140 USD in 7 days
5.9
5.9

Have been working on .NET applications for more than 20 years. Can develop this for you along with WhatsApp integration.
$140 USD in 14 days
6.1
6.1

I already run my business on a desktop-based invoicing tool and can supply its full source code. I want an exact replica built from that code... a like-for-like rebuild plus a WhatsApp layer for sending invoices and reminders. Since you can hand over the source, schema, and a walkthrough video, week one I'd port the existing screens 1:1 and prove client management, payment tracking, and recurring invoices behave identically before touching anything new. For stack, I'd keep it native Windows in C#/.NET (WPF or WinForms, matching what your current code uses) so the interface and workflow feel identical to today. No rewrite for its own sake, just cleanup where it helps maintainability. Here's the plan: 1. Port the existing app screen by screen, wired to your schema, so every current function matches the original. 2. Add the WhatsApp module using the official Cloud API, tied directly into the invoice send and reminder flows. 3. Package a signed Windows installer plus a short setup and user guide so you can ship future updates in-house. I build full-stack products end to end, including a multi-org SaaS with billing and automated workflows, so the recurring-invoice and reminder logic is familiar territory. Done = the rebuilt app passes a side-by-side check against your current tool on every screen, and an invoice or reminder sends over WhatsApp from inside the app. One thing to confirm so I can lock the WhatsApp piece: do you want messages sent from an official WhatsApp Business API number (template approval needed for reminders), or from your own existing WhatsApp number via an approved SDK? The choice changes setup and ongoing cost. P.S. WhatsApp blocks free-form template messages outside a 24-hour window, so payment reminders need pre-approved message templates. I'd get those submitted on day one since approval can take a couple of days. Waqar
$162 USD in 7 days
5.6
5.6

✋ Hi there. I can rebuild your desktop invoicing tool for Windows with the same workflow and screens, while adding WhatsApp sharing for invoices and payment reminders. ✔️ I have solid experience working on Windows desktop apps, invoice systems, database-driven tools, installer builds, and third-party API integrations. In a previous project, I updated a billing application with client records, payment tracking, recurring invoices, PDF invoice generation, and message-based reminder features. ✔️ For your project, I will review your source code, database schema, and walkthrough video, then rebuild or refactor the app while keeping the user experience familiar. I will preserve client management, payments, recurring invoices, reports, and all current business logic. ✔️ I will also add WhatsApp messaging using the official API or an approved SDK, connect it to invoice sending and reminder flows, and provide a Windows installer, signed executable, clean source code, and setup guide. Let’s chat to discuss your project in more detail. Best regards, Mykhaylo
$140 USD in 7 days
5.6
5.6

Being in the industry for 14 years as a Full Stack Developer, I have amassed an extensive skillset including proficiency in .NET, C#, and software architecture that are not only aligned with your project requirements but also differentiate me from the rest. My experience in creating intelligent, scalable applications will ensure that your existing desktop invoicing tool is rebuilt with unfaltering accuracy, retaining all the crucial features while upgrading it to include the WhatsApp integration.
$100 USD in 3 days
6.1
6.1

Hello, I understand everything that you need integrate WhatsApp to share invoices or payment reminders directly from the app with your clients, I am ready to do that by many ways the best of all is using the official API please contact me to discuss more about your project
$140 USD in 7 days
5.4
5.4

✋ Hi There!!! ✋ THE PROJECT GOAL:- EXACT DESKTOP INVOICE CLONE WITH WHATSAPP INTEGRATION FOR WINDOWS WITH SAME WORKFLOW AND INTERFACE I have carefully read project requirement and understand you want identical desktop system with added WhatsApp messaging flow. I am best fit because I deliver clean scalable desktop systems with strong integration expertise. • Windows installer and signed executable with identical UI and workflow • WhatsApp API integration for invoices and payment reminders • Complete source code, database management, testing and documentation I provide UI design, database management, testing, full source code delivery and deployment support. I have 9+ years experience as a full stack developer and have built invoicing and ERP desktop tools with API integrations. I have completed similar invoicing systems and WhatsApp automation projects. Looking forward to chat with you for make a deal Best Regards Elisha Mariam
$251 USD in 11 days
4.9
4.9

Hello, I can help rebuild your existing Windows desktop invoicing application from the provided source code while keeping the current workflow, screens, and user experience as close to the original as possible. I have experience with C#/.NET desktop applications, database-driven business software, invoicing workflows, and API integrations. My approach would be to first review the existing project structure, database schema, and walkthrough video, then reproduce the current functionality carefully before adding the WhatsApp messaging layer for invoice sharing and payment reminders. For the WhatsApp integration, I would recommend using the official WhatsApp Business API or an approved provider, depending on your current account setup and messaging requirements. I can integrate this into the invoice send and reminder flow while keeping the code clean and maintainable. The final delivery will include the updated source code, a Windows installer, setup notes, and a brief user/developer guide. If you already have a code-signing certificate, I can use it for the executable; otherwise, I can provide the installer ready for signing. I’m available to start immediately and can deliver the rebuild and integration in clear milestones. Best regards, Albert C.
$220 USD in 7 days
4.6
4.6

I am .NET developer , I would be able to help you. Can you please let me know what is current tech stack of your application.
$140 USD in 7 days
4.6
4.6

With a strong emphasis on API integration, I intend to transform your existing desktop invoicing tool into an efficiently engineered powerhouse that can seamlessly integrate with WhatsApp. My expertise extends far beyond replicating source code—I focus on breathing new life into digital platforms by integrating cutting-edge features while maintaining the familiar user experience. Working with various tech stacks over the years has equipped me for any challenges that may arise during your project. Whether it's Laravel for the backend or Flutter Apps for the frontend, I'll ensure a reliable, user-friendly system that matches every aspect of your current platform and still delivers the novel functionality you seek. As part of my service, you can also rely on me to provide a compiled Windows installer and signed executable, well-commented source code, a fully functional WhatsApp messaging module, as well as a detailed set-up and user guide. What sets me apart in this competitive landscape is my consistent communication style, professional workflow, and unwavering commitment to quality. Get ready to transition into a streamlined digital experience with my assistance. Let's connect the dots!
$30 USD in 1 day
4.6
4.6

I understand you're looking for a precise desktop invoice clone with added WhatsApp functionality, leveraging your existing source code. My experience building complex desktop applications and integrating third-party APIs, similar to the requirement of replicating intricate workflows and UI elements, assures me I can deliver an exact replica of your current invoicing tool. My approach will involve a thorough analysis of your provided source code to understand its architecture and functionalities. I will then use a suitable .NET framework (e.g., WPF or WinForms, depending on your current stack) to rebuild the application, ensuring pixel-perfect replication of the UI and all existing features. For WhatsApp integration, I'll utilize the official WhatsApp Business API or a reputable third-party service, implementing secure and efficient message sending for invoices and reminders directly from the application. The plan includes rigorous testing on Windows to guarantee reliability and a smooth user experience. To ensure optimal alignment, could you clarify if your current invoicing tool uses a specific database technology? Also, are there any particular security considerations for the WhatsApp integration you'd like to prioritize? I'm confident I can meet your requirements and would be happy to discuss the project in more detail.
$200 USD in 21 days
4.1
4.1

⚠️ If you're not happy, you don’t pay. ⚠️ Hi there, thank you for checking my proposal and sharing the detailed project brief. I can build your desktop-based invoicing tool replica using your existing source code while integrating a seamless WhatsApp module for direct sharing. The new build will maintain all current features like client management, payment tracking, and recurring invoices. I will deliver: • Compiled Windows installer and signed executable • Complete, well-commented source code • WhatsApp messaging module integrated into invoice flows • Setup & user guide for future updates You will also receive a brief setup guide for deploying future updates. I am confident in executing your vision efficiently. Looking forward to discussing timelines and next steps. Best regards, Chirag.
$200 USD in 7 days
4.3
4.3

Drawing upon my extensive experience building sophisticated and reliable desktop applications, particularly in C# and PHP, I am extremely confident in my ability to fulfill the requirements of your project. My particular strength and expertise lie in rebuilding and enhancing existing applications, a skill that you will find invaluable as you seek to seamlessly integrate WhatsApp functionality into your current invoicing tool. In addition to my technical prowess, I also place an enormous emphasis on clear documentation and detailed walkthroughs, key deliverables that were outlined for this project. Your satisfaction as the end-user matters greatly to me; I pledge to develop a brief yet comprehensive setup and user guide that will enable you to easily manage and update this application autonomously in the future. Lastly, I understand the importance of meeting both functional objectives and deadlines. My results-driven approach has allowed me to consistently deliver high-quality code within agreed-upon timelines while exceeding client expectations. In selecting me for this project, you are choosing a competent professional who not only incorporates existing code seamlessly but takes your unique user experience into account throughout the development process.
$180 USD in 2 days
4.3
4.3

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