Build Comprehensive Backend Services

@Microlent

Hello, I can architect and build your full cross-border payment infrastructure with B04 as a hardened, audit-grade core service. I specialize in high-integrity financial backends with strict idempotency, reconciliation accuracy, and event traceability. Approach: • B04 Matcher with HMAC-SHA256 webhook validation, regex ref extraction, exact/partial/over reconciliation, 3-queue routing, float ledger, admin force-match/refund, 100% edge-case tests • Rate Lock Engine with XE + Cargills fetch, 24h dual-rate lock, expiry enforcement • USDC module via Circle API with blockchain audit logging • Wallet, FOREX routing, and balance monitor with threshold alerts • CI/CD, staging, Sentry, Slack alerts, full load testing Built for scale, compliance, and zero-duplication guarantees. If you share expected volume and settlement flow, I’ll finalize the architecture immediately. Best regards, Jenifer

@OutsourceMan

Hello, This is a serious fintech system and I understand this is an extension of a live .NET production backend (PCMCoreService), not a greenfield build. I have experience working on regulated payment platforms, blockchain audit integrations, and Vue-based PWAs. Approach: • Deep codebase audit (services, settlement flow, webhook handling, ledger writes) • Review integrations: Moneris (Interac Autodeposit), XE rates, Circle USDC, Cargills FOREX, WhatsApp Business API, Vonage • Validate settlement lifecycle (CAD → FX → USD/LKR → wallet → USDC ledger record) • Harden error handling, idempotency, and reconciliation logic PWA Extension Plan (6 Months): Phase 1: Architecture review + API contract stabilization Phase 2: Vue.js PWA enhancement (offline support, push, improved UX flows) Phase 3: Wallet + ledger transparency dashboard (USDC audit visibility) Phase 4: Performance, security hardening, load testing Phase 5: Compliance logging & monitoring improvements Tech Focus: • .NET service layer extensions (clean separation, test coverage) • Secure API authentication + rate limiting • Blockchain transaction verification checks • Production-ready CI/CD & staging workflows I am comfortable reading complex financial codebases and extending them safely without breaking settlement logic. Available for a structured 6-month engagement with milestone-based delivery. Best regards, Raman

@caroldata

Having been in the IT industry for over a decade, we at Carol Data Technology have amassed invaluable expertise in the exact fields required for this project. Our company, being ISO 9001:2008 Certified, emphasizes quality and precision in all our services. We specialize in Backend Development and have rendered our skills across various platforms from NodeJS to PHP and several others indicated as requirements. From the Interac Reference Code Matcher to the Bank Deposit Offload, each of these backend services requires utmost precision and meticulousness which we offer clearly. Our extensive knowledge of API Development is directly relevant to integrating with XE Currency API, Circle USDC API, Moneris Autodeposit webhook, WhatsApp Business API, and Vonage SMS. We are adept at setting up CI/CD pipeline, staging environments, Sentry error monitoring as well as Slack alerting which will be essential for this project. Moreover, my team is well versed in writing unit and load tests to ensure 100% edge case coverage as you've specified for B04 matching scenarios. As an added advantage, we also provide continued support following project delivery; an assurance that we take responsibilities of our work serious. Make the choice that guarantees; daily project progress reports, clear communication lines throughout your projects. Choose Carol Data Technology to build robust backend services that meet your every expectation!

@vishal1145

Your Interac Autodeposit flow will fail compliance audits if you're not logging every state transition between payment initiation and USDC settlement. Most remittance platforms I've worked with get flagged during FinTRAC reviews because they treat blockchain ledgers as append-only without reconciling off-chain payment states. Before extending PCMCoreService, I need clarity on two things: What's your current error rate when Moneris webhooks arrive out of order during high-volume periods? And does your USDC audit ledger handle rollback scenarios when XE currency rates change between request and settlement? Here's the architectural approach: - PHP + MYSQL: Refactor transaction state machines to enforce idempotency across Interac callbacks, ensuring duplicate e-Transfers don't create phantom wallet credits. - API DEVELOPMENT: Build middleware that validates Circle USDC transaction hashes against your MySQL records before marking settlements as complete, preventing ledger drift. - PAYMENT PROCESSING: Implement retry logic with exponential backoff for Cargills FOREX API failures, logging every attempt to satisfy cross-border audit trails. - CI/CD: Set up staging pipelines that replay production webhook sequences to catch race conditions before they hit live remittance flows. - XML + BACKEND DEVELOPMENT: Parse and validate Moneris response schemas to handle edge cases like partial refunds or expired Autodeposit registrations. I've built similar fintech integrations for 2 remittance platforms processing $4M monthly volume. I don't take on projects where payment reconciliation logic isn't bulletproof. Let's schedule a 20-minute technical call to walk through your current PCMCoreService architecture and identify failure points before committing to a 6-month build.

@KarthikTechCon

Hi, I’m Karthik – Backend Architect with 15+ years experience in fintech, remittance & blockchain-integrated systems. Your QicSEND SL platform is exactly the kind of production-grade system I specialize in — extending and hardening existing codebases, not rebuilding from scratch. I have strong experience with: • .NET Core service architectures (API, background workers, secure settlement flows) • Vue.js / PWA builds with offline-ready architecture • Payment integrations (Interac, Moneris-like gateways) • FX rate services (XE-style feeds) • USDC / blockchain audit logging (Circle APIs, ledger reconciliation) • WhatsApp Business & Vonage messaging workflows For this 6-month engagement, I will: ✔ Deep-dive into PCMCoreService and document current flows ✔ Strengthen settlement orchestration (CAD → USD/LKR → USDC ledger) ✔ Implement resilient audit logging & reconciliation layers ✔ Optimize PWA performance & security ✔ Ensure compliance-grade transaction traceability I focus on clean extensions, secure financial logic, and production stability. Available to start immediately and commit long-term. Happy to review architecture and share relevant fintech work in chat.

@ankitchugh006

Draw on my extensive experience as a web developer and the wide range of skills I have honed over 7+ years; I believe I can bring significant value to your project. As someone with a demonstrated ability to build high-performing, robust websites, I can confidently take charge of creating comprehensive backend services that align perfectly with your specific requirements for each project, whether it's the Interac Reference Code Matcher (B04), Rate Lock Engine (B02), USDC Settlement Module (B08), Cargills FOREX Account Manager (B09), or others. My familiarity with multiple APIs including XE Currency, Circle USDC, Moneris Autodeposit, WhatsApp Business and Vonage SMS ensures seamless integration, while my expertise in developing in PHP would prove crucial for effective backend design and development. Additionally with strong exposure in setting up CI/CD pipelines, staging environments, Sentry error monitoring and Slack alerting for critical payment events, everything will be streamlined to optimize productivity.

@monicasynthesis

Hello, I’ve read your description and understand you need a developer to extend your existing .NET backend and Vue.js PWA for QicSEND SL, a cross-border remittance platform. With 5+ years in full-stack development, I’ve maintained and enhanced complex production apps with multiple integrations. What I can help you with: • Extend your current codebase and build a responsive PWA • Work with integrations like Moneris, XE, Circle USDC, Cargills FOREX, WhatsApp, and Vonage • Ensure secure, accurate transactions over the 6-month project Warm regards, Monica Bhatia

@chiragardeshna

Hi there, You are building a cross-border payment backend where a single matching error or rate lock failure has real financial consequences this is not a project where close enough is acceptable at any layer. I have built financial backend services handling webhook validation with HMAC verification, idempotency logic on transaction IDs, and multi-queue routing where every edge case was covered by tests before anything touched a live payment. I would start with B04 since everything downstream depends on reconciliation being airtight HMAC validation, regex extraction, three-queue routing, and every matching scenario unit tested to 100% edge case coverage before staging. B02 rate lock and B08 USDC settlement would follow in parallel once the matching engine is stable, with the blockchain audit ledger and Circle API integration built alongside. Remaining services would be sequenced so each one has clean inputs from the service below it before it is wired up. CI/CD, Sentry, and Slack alerting would be live from the first deployment so nothing fails silently in staging. One question does Moneris send a test webhook environment you can share early, or would B04 development need to start against mocked payloads until the live credentials are ready? Happy to jump on a quick call to go through the full service map and agree on a build sequence before anything starts. Regards Chirag

@bhartimalu

Hi there, I can build and extend your comprehensive backend services for your cross‑border payment platform — including reading/understanding the existing .NET backend, adding robust modules, API integrations (Moneris, XE, Circle, WhatsApp, Vonage), secure payment logic, scalable architecture, CI/CD setup, and thorough testing. I deliver clean, maintainable, well‑documented code and can align with your production requirements and timelines. Regards, Bharti

@arshig8

Hello, I understand that QicSEND SL is a production-ready cross-border remittance platform enabling fast, low-cost transfers from Canada to Sri Lanka, built on an existing .NET backend (PCMCoreService) and Vue.js PWA. The system integrates Moneris (Interac Autodeposit), XE Currency, Circle USDC, Cargills FOREX, WhatsApp Business API, and Vonage, with USDC blockchain-based audit logging. You need an experienced developer to read, understand, and extend the current codebase over a 6-month roadmap — not build from scratch — and further strengthen the Progressive Web App. With strong experience in backend development, API integrations, payment processing, and scalable system architecture, I have worked on financial and transactional platforms involving third-party gateways, real-time currency handling, wallet systems, and CI/CD pipelines. My expertise in PHP, MySQL, XML, API development, and production-grade architecture allows me to safely extend complex systems while maintaining performance, security, and compliance. I am also comfortable working with existing enterprise codebases and improving modularity, logging, and deployment workflows. Could you please clarify whether the immediate focus is on enhancing settlement workflows, expanding wallet functionality, or optimizing the PWA performance and UX? I would be happy to review the existing architecture and discuss a structured development plan. Let’s connect and take this forward. Best regards, Arshiya

@shibbuquadir

As a freelancer and an integral part of Paper Perfect, delivering highly efficient, bespoke backend services that align with your unique needs is ingrained in my DNA. Throughout my extensive career, I've mastered the art of API & Backend Development, and PHP which are crucial skills for successfully executing every task specified in your project. From Moneris webhook validation to maintaining float account ledgers, I'm well-versed with every requirement. What sets me apart is not just my technical excellence but also my deep understanding of the importance of robust systems to a business. I've been able to deliver scalable solutions while ensuring stringent security checks such as HMAC-SHA256 validation for Moneris webhooks. My keen eye for detail has also enabled me to maintain 100% edge case coverage through thoroughly writing unit and load tests, preparing for all possible scenarios. Lastly, my proficiency in setting up CI/CD pipeline, staging environments and integrating with various APIs can help streamline your operations and enhance user experience. I have also worked with Vonage SMS and WhatsApp Business API similar to what you require. Partnering with me will not only bring unmatched technical skills but absolute dedication towards project timelines and quality outputs. Let's leverage this opportunity to build a robust, efficient backend system together!

@ritikgarg55

Hi there, my name is Ritik Garg and I'm a Full-Stack/Backend Developer from India. I have over 5 years of experience working with Python, Django, Restful APIs, Data Mining, Flask, Scrapy, Selenium, Flask, Node JS, Angular, React, AWS, DevOps, Azure, request, threading and selenium. My ultimate goal is to provide my clients with more than 100% satisfaction by implementing their ideas and helping their business thrive and grow. I always make sure to understand my clients' needs accurately and recommend the best approach for their project. I am always ready to take on any project and deliver it to the best of my abilities. Here are my core skills: - VueJS | JavaScript | Angular | ReactJs - NodeJS | Python - Bootstrap | CSS | CSS3 | HTML | HTML5 - Django | Flask - MySQL | MongoDB | SQLite | Postgres SQL - AWS, EC2, S3 DevOps Deployment

@murtuza90

Hello, I understand QicSEND SL is a live cross-border remittance platform built on .NET (PCMCoreService) and Vue.js PWA, integrating Moneris, XE, Circle USDC, Cargills FOREX, WhatsApp Business API, and Vonage. The key challenge is safely extending a production system, maintaining transaction integrity, blockchain audit logging, currency accuracy, and real-time settlement flows without disrupting operations. With 11 years of expertise in .NET, Vue.js, fintech integrations, APIs, and scalable PWA development, I can confidently read, enhance, and optimize your existing codebase. I’m ready for this 6-month engagement. Let’s discuss roadmap and priorities.

@Himanshu123gupta

With my extensive experience in back-end services, I am confident I will be the ideal candidate for your project. I have worked with various stack technologies such as PHP, MySQL, laravel and much more, making me familiar with your current .NET backend (PCMCoreService). My proficiency in these programming languages would enable me to extend the production codebase efficiently. In addition, my familiarity with Vue.js PWA would significantly contribute to building the progressive webapp you require for this project. My specialization in not just backend development but also frontend technologies like React.js and Vue.js assures a holistic approach towards web development. Ultimately, I understand the importance of interconnectivity within a remittance platform; hence my fluency with several APIs including Moneris for Interac Autodeposit would facilitate a seamless integration process. In conclusion, choosing me guarantees a knowledgeable professional who can hit the ground running, finish your project within given 6 months and deliver exceptional work exceeding your expectations. Let's discuss your vision in detail!

@Hemantt841

I understand you require a robust backend to handle complex payment processing tasks like Moneris webhook validation with HMAC-SHA256, regex extraction of reference codes, and multi-queue operations for unmatched, partial, and overpayment scenarios. You also need precise integration of APIs like XE Currency for rate locking and Circle API for USDC settlement, alongside comprehensive error monitoring and CI/CD setup. With over 15 years of experience and more than 200 projects completed, I specialize in backend development using PHP and MySQL, API integration, and cloud-based DevOps practices. My expertise ensures reliable payment processing systems with secure transaction handling and scalable architecture tailored to your needs. I will build each service module methodically, starting with the Interac Reference Code Matcher (B04), implementing idempotency and detailed unit tests for all edge cases before progressing to the Rate Lock Engine and USDC Settlement Module. The workflow will incorporate Moneris, XE, and Circle API integrations, with CI/CD pipelines and Sentry monitoring set up for seamless deployment and error tracking, aiming for delivery within the agreed timeframe. Let’s discuss how I can help bring your backend services to full functionality with precision and reliability.

@iamthepakSharma

I’ve reviewed your requirement and this is my understanding: you need an experienced backend engineer to own and build multiple critical payment and settlement services, including the Interac Reference Code Matcher (B04) as the highest priority. I have 8+ years of experience building complex fintech and payment backend systems with PHP/Laravel and Node.js, integrating multiple third-party APIs, implementing transactional idempotency, and designing robust reconciliation workflows. I have built systems for real-time currency conversions, USDC settlements, ledger management, and multi-queue payment routing, with CI/CD pipelines, monitoring, and comprehensive unit/load testing. I’m available to start immediately and can deliver production-ready, fully tested, and monitored backend services, starting with B04, followed by the remaining modules in a structured, milestone-driven development plan. Best Regards, Deepak

@shailender18

Hi, I am a Senior full-stack developer with strong experience in .NET backend systems, fintech integrations, and Vue.js applications. I understand this is an extension of an existing production platform — not a greenfield build. I’m comfortable reading and working within established codebases, especially service-driven .NET architectures. For QicSEND SL, I can: Work directly inside the existing PCMCoreService (.NET) and Vue.js PWA Extend payment workflows around Interac (Moneris Autodeposit), XE Currency, Circle USDC, and FOREX integrations Maintain blockchain settlement logging via USDC ledger integration Improve and harden the Progressive Web App for performance and reliability Ensure secure transaction handling, proper logging, and compliance-aware coding practices I have experience with financial APIs, real-time currency handling, webhook processing, and transactional systems where accuracy and auditability are critical. For a 6-month engagement, I can commit long-term, follow structured sprint cycles, and work within your existing deployment and version control workflow. After reviewing the current codebase and architecture, I can propose a phased enhancement plan with milestones. Ready to review access and begin immediately. Best, Shailender

@OwlWingDesigns

As an experienced full-stack developer, I have a proven track record of efficiently diagnosing and resolving tough issues with existing systems, making me the ideal candidate to read, understand, and extend your current .NET backend for QicS

@ayushmaanksahu4

Hi there, You’re absolutely in the RIGHT PLACE. I’ve delivered SIMILAR PROJECTS multiple times and know EXACTLY how to execute this efficiently and correctly from day one. To lock down the SCOPE, TIMELINE, AND PRICING, I’ll need to ask you a few key questions. Unfortunately, Freelancer’s 1500 CHARACTER LIMIT doesn’t allow me to break everything down properly here. Let’s jump on CHAT so I can show you my PROVEN PAST WORK, walk you through the REAL RESULTS I’ve delivered, and outline a CLEAR ACTION PLAN for your project. You’ll immediately see why my approach is DIFFERENT and EFFECTIVE. If you’re serious about getting this done RIGHT, I’m ready to move forward. Looking forward to CONNECTING and WINNING TOGETHER. Cheers, Aayushaman Sahu