Senior Fintech Dev - Microservices, eWallet, Banking

@corpmember29

FINTECH BACKENDS DEMAND MORE THAN MICROSERVICES — THEY REQUIRE TRANSACTIONAL ACCURACY, SECURITY, AND RELIABLE BANK INTEGRATIONS. I am a Senior Backend Developer with 12+ years of experience, including extensive work on fintech platforms involving digital wallets, payment processing, banking integrations, ledger systems, reconciliation, and high-volume transaction services. ### Relevant Experience: ✔ eWallet platforms (wallet balances, holds, settlements, virtual ledgers) ✔ Bank integrations via REST, SOAP, ISO/file-based exchanges ✔ Spring Boot, Spring Cloud, Microservices Architecture ✔ Oracle Database, PL/SQL, Stored Procedures, Performance Tuning ✔ KYC/AML workflows, audit logging, reconciliation engines ✔ OAuth2/JWT, encryption, PCI-DSS-aware implementations ### Fintech Challenge Solved: Implemented idempotent transaction processing for a wallet platform handling concurrent payment callbacks from multiple providers. Using transaction references, distributed locking, and ledger validation, we eliminated duplicate credits and reconciliation mismatches. I can contribute across architecture, development, bank integrations, performance optimization, testing, deployment, and production support while maintaining the reliability expected in financial systems. I would be happy to discuss your existing architecture, banking partners, and delivery roadmap in detail.

@softsolution2000

With over 15 years of experience in backend development and a successful track record of completing a wide variety of projects, I am confident I possess the necessary skills to excel in your role. My professional endeavors have gravitated towards Fintech for the last three years, which has afforded me invaluable experience in building high-performing platforms similar to yours. I have successfully integrated with multiple banking institutions using REST APIs and can effortlessly adapt to other protocols such as SOAP and file-based systems. Moreover, my comprehensive understanding of eWallet systems is another key selling point for you. I have extensively worked on functionalities such as balance management, transaction idempotency, and virtual ledgers, all of which are crucial aspects for your project. An added advantage is my intricate knowledge of financial development workflows like double-entry accounting and reconciliations that provide me the unique ability to mitigate potential challenges proactively. Finally, my profile team promises 100% client satisfaction with a money-back guarantee. This coupled with my flexible payment terms that allow you to review progress before making any payments exhibit the trust I place in my skills and my commitment to deliver high-quality works before the stipulated deadlines. Pick me and together we will build eine skalierbare und sichere Software für erfolgreiches Geschäftswachstum.

@offshore9006

Hi there, We are a team of Fintech developers, and we have worked in Loan & Mortgage and Microfinance. Would love to share the case studies. Look forward to hearing from you!! Best,

@KarthikTechCon

Hello, I'm Karthik, a Software Architect and Senior Java Developer with 15+ years of experience in enterprise applications, microservices, payment processing, and financial transaction systems. My expertise includes Spring Boot, Spring Cloud, REST/SOAP integrations, Oracle Database, distributed systems, and high-volume transaction processing. I have worked on wallet-like transaction platforms, payment workflows, reconciliation processes, API integrations, and secure financial applications. ✔ Spring Boot & Microservices Architecture ✔ Oracle PL/SQL, Performance Tuning & Transaction Management ✔ REST/SOAP Banking & Third-Party Integrations ✔ OAuth2, JWT, Encryption & Audit Logging ✔ Docker, Kubernetes & Cloud Deployments ✔ OpenAPI/Swagger Documentation A key challenge I solved involved preventing duplicate financial transactions in distributed services by implementing idempotency keys, transaction state tracking, and reconciliation mechanisms, ensuring consistency even during network failures and retries. I am comfortable contributing 30–40 hours per week and collaborating with distributed teams through clear written and verbal communication. I would be happy to discuss your banking integrations, wallet architecture, and technical requirements in detail. Best Regards, Karthik 15+ Years Experience | Java, Microservices & Enterprise Solutions

@belotefreelancer

"I have gone through your description. "This is my area of specialization, i can get it done 100 % perfectly well. Please ping me in person. I can help you to complete all tasks. I have hands-on experience in this field. We have already done similar types of projects. Connect with us for more details. Rest assured your satisfaction is guaranteed." Looking forward to your response." Thank you for your time and I am confident that we will be a great fit for this project. Best,

@osamak74

Hi, I’m Osama from Virginia. I understand that you need a senior backend developer who can strengthen a mission-critical fintech platform with Spring Boot microservices, eWallet logic, and bank integrations, and the main priority is to keep transactions reliable, auditable, and consistent under heavy financial load. I can help build and improve this in a clean, secure, and maintainable way without unnecessary rebuilding. I have experience with Java, Spring Boot, REST APIs, Oracle, Git, Docker, and microservice architecture. For this project, I would first review the current services, database structure, and integration flow, then focus on wallet transactions, ledger consistency, bank connectivity, and reconciliation paths, with proper testing and documentation throughout. My approach would be to map the existing financial workflows, identify gaps in idempotency and transaction safety, implement the required services with clear API contracts, and validate the important bank/eWallet flows with integration tests. I can also keep the codebase organized for future extension and handover. I’m available to start anytime and can work full-time. I look forward to discussing the project with you. Regards, Osama

@albertc1996

Hello, I am a Senior Java Developer with more than 7 years of experience in enterprise software development, including extensive work within banking and financial services environments. My background includes designing and implementing high-volume transaction processing systems, Spring Boot microservices, Oracle-based financial applications, and integrations with banking and payment platforms. After reviewing your requirements, I am confident that my experience aligns well with the needs of your fintech platform, particularly in the areas of wallet management, banking integrations, transaction consistency, and secure financial system development. Relevant Fintech Experience Over the past several years, I have worked on financial and banking platforms involving: • Payment processing and transaction management • Core banking integrations • Financial messaging and API integrations • High-volume Oracle database systems • Distributed microservices architectures • Secure financial workflows and auditability • Financial reconciliation and transaction consistency Examples of Fintech Projects • Banking Platform – Developed and maintained enterprise banking services responsible for customer account management, transaction processing, and integration with external banking systems. • Financial Transaction Platform – Designed and implemented microservices handling payment workflows, transaction validation, audit trails, and settlement-related processes. • Digital Financial Services Integration – Built backend services integrating with external financial providers using REST APIs and secure communication channels. Technical Expertise Relevant to Your Project Backend & Microservices • Java 17 • Spring Boot • Spring Cloud • REST APIs • Microservices Architecture • API Gateway • Service Discovery • Circuit Breakers • Distributed Systems Design Oracle Database Extensive hands-on experience with Oracle databases in financial environments, including: • PL/SQL development • Stored Procedures and Packages • Query Optimization • Indexing Strategies • Performance Tuning • Transaction Isolation Levels • Concurrency Management • High-volume Transaction Processing • Complex Financial Reporting Queries Banking & Financial Integrations My experience includes integrating backend services with external financial systems through: • REST APIs • SOAP Services • Secure File-Based Exchanges • Scheduled Batch Processing • Authentication and Authorization Workflows Security & Compliance I regularly implement security controls required in financial applications, including: • OAuth2 • JWT Authentication • Encryption in Transit • Encryption at Rest • Audit Logging • Role-Based Access Control • Secure API Design Approach to eWallet and Financial Transactions For wallet and payment systems, I focus heavily on: • Transaction Idempotency • Duplicate Transaction Prevention • Consistency Guarantees • Ledger Integrity • Reconciliation Processes • Reliable Retry Mechanisms • Auditability and Traceability Example Challenge Solved One of the most critical challenges I addressed involved preventing duplicate financial transactions in a distributed microservices environment. The issue occurred when network failures caused clients to retry payment requests, creating the risk of duplicate processing. To solve this, I implemented: • Idempotency Keys • Transaction State Tracking • Database-Level Constraints • Distributed Validation Logic • Retry-Safe Processing Flows This ensured that repeated requests could never create duplicate financial transactions, even during service failures or communication interruptions. Deliverables I can provide: • Production-ready Spring Boot microservices • Source code via GitHub/GitLab • OpenAPI / Swagger documentation • Database migration scripts • Unit and Integration Test Suites • Deployment Documentation • Operational Support during rollout Availability & Rate Availability: 30–40 hours per week Hourly Rate: 10-15 Closing I am interested in long-term collaboration and would be pleased to contribute to the success of your fintech platform. My combination of enterprise Java expertise, banking domain knowledge, Oracle experience, and microservices architecture background allows me to deliver secure, scalable, and maintainable financial solutions. I would be happy to discuss your architecture, integration requirements, and project roadmap in more detail. Kind regards, Albert C Senior Java Developer

@shibbuquadir

With over a decade of experience in backend development, we at Paper Perfect have successfully catered to numerous clients across various industries – including the Fintech sector. One shining example would be our anonymized work with a well-known payment solutions provider where we developed and integrated complex eWallet systems. This endeavor has improved our understanding of modern financial workflows, enriching our skillset on topics like double-entry accounting, reconciliation, and reporting. One particular challenge we faced was ensuring idempotency in microservices while avoiding duplicate transactions during banking integrations - a problem many fintech firms encounter nowadays. Our ability to overcome such obstacles with creative and robust solutions is what sets us apart as reputable professionals. In terms of tech proficiency, we are well-versed in utilizing Spring Boot for high-transaction financial systems with solid knowledge of Spring Cloud microservices patterns. Moreover, we have hands-on familiarity in dealing with Oracle Databases especially in heavy transaction scenarios improving efficiency through data partitioning. All this combined puts us in an excellent position to provide you with the necessary support in building state-of-the-art digital wallet platforms, handling bank integrations and ensuring the highest security measures including encryption at rest/in transit, audit logging, among others you seek вы

@Govind7877190814

Hi, I would like to grab this opportunity and will work till you get 100% satisfied with my work. I just applied after read your job posting carefully and I believe that I am good fit to your project. I'm a serious bidder. I will satisfy you with my high skills! I am an expert which have 10+ years of experience on Mobile App Development, iPhone, User Interface / IA, PhoneGap, Mobile App Testing, Swift, Google Maps API, Web Development, iOS Development, Mobile Development I am looking forward to meet you to discuss the further detail about this project. Looking forward to hearing from you. Warm Regards

@ChiefKnox32

Hi, "eWallet systems" built on Spring Boot microservices demand double-entry ledger integrity at the database level because application-layer rollbacks alone won't catch split-brain failures across distributed services during settlement windows. I've spent 6 of the past 8 years in Fintech backend roles: Spring Boot and Spring Cloud microservices for digital wallets, bank REST and SOAP integrations for account validation and fund transfers, and Oracle PL/SQL managing transaction isolation and reconciliation under load. On the challenge you asked about: I solved a duplicate transaction issue where the partner's API timed out but had already posted the debit. The fix was idempotency keys persisted in Oracle before the outbound call, checked on retry, with a compensating ledger entry if the debit had cleared. No duplicate, no manual reconciliation. I've also shipped KYC/AML workflows, OAuth2/JWT auth, audit logging, and PCI-DSS-aware encryption in the same codebases. OpenAPI docs, schema migration scripts, and integration test suites are standard on every handoff. Rate is $12/hour. Available 35 to 40 hours per week immediately. Best regards

@rbtech1984

Hi There!!! ★★★★ ( Financial transaction idempotency and dual entry ledger architect ) ★★★★ You need a Senior Fintech Developer to design Spring Boot microservices for high-transaction eWallet and banking integrations. The platform requires multi-bank API syncs, Oracle DB transaction isolation, automated ledger reconciliation, and strict PCI-DSS security compliance. Services based on your details: ⚜ Designing Spring Boot microservices with circuit breaker patterns ⚜ High-transaction eWallet balance tracking and virtual ledger entries ⚜ Multi-bank REST/SOAP integrations for validation and fund transfers ⚜ Oracle DB performance tuning, partitioning, and PL/SQL procedures ⚜ Implementing automated KYC/AML workflows and settlement cycles ⚜ Securing financial data using OAuth2, JWT, and transit encryption ⚜ Delivering OpenAPI docs, migration scripts, and integration test suites My plan is to deploy robust Spring Cloud microservices utilizing an API Gateway to handle transaction flows cleanly. I will implement a double-entry ledger design with unique idempotency keys in Oracle SQL to entirely prevent duplicate transactions and ensure zero reconciliation mismatch during high concurrency. I am available for 35 hours/week at an hourly rate of $15 USD. I have integrated tier-1 banking systems and payment gateways using strict transactional isolation levels. Let connect in chat to discuss your system architecture! Warm Regards, Farhin B.

@mundadiya

As a highly adept Senior Backend Developer, I am confident in my ability to tackle your Fintech project effectively and efficiently. For over five years, my focus has been on fintech specifically, including banks, payments, wallets, exchanges, and lending. My experience constructing resilient eWallet systems and seamlessly integrating with core banking systems make me an excellent fit for your current project. Moreover, my expertise in handling financial workflows such as double-entry accounting, reconciliation as well as maintaining database-centric financial data consistency can provide significant value to your mission-critical platform. Regarding technical skills, I have extensive hands-on experience with Spring Boot and Spring Cloud—necessary tools for building reliable microservices, including service discovery, API gateway, and circuit breakers. My proficiency with Oracle Database and PL/SQL helps in effectively managing high-volume transactions and ensuring database performance optimization. In addition to this, my familiarity with version control (Git), Maven/Gradle and Docker/Kubernetes is an added advantage.

@rafaels170

Hi, I’m a backend developer with 6+ years in Fintech, building Spring Boot microservices, eWallet platforms, and bank integrations. Experienced with Oracle (PL/SQL, high-volume transactions), API integrations, idempotent transactions, and secure workflows (KYC, AML, PCI-DSS). I deliver tested, documented, scalable microservices. Available 30–40 hrs/week, excited to tackle complex banking flows with you.

@engruhulajom

Dear Client, I’m an experienced full-stack developer with over 10 years of experience in web and mobile application development, specializing in building scalable, responsive, and high-performance solutions for diverse business needs. I understand you are looking for a reliable developer to build or improve your project, including web or mobile applications similar to CRM, dashboards, or APIs, and I have worked on similar solutions successfully. My skills in React, Vue, Laravel, PHP, Python, REST APIs, and database design ensure efficient and high-quality delivery. Feel free to share more details or ask questions. I’m ready to refine my approach to match your exact requirements. Looking forward to working with you. Best regards, Md Ruhul Ajom

@sgwtechnology

Hello, I am a senior backend developer with strong experience building fintech platforms, payment systems, and microservice architectures using Spring Boot. My background includes wallet management, transaction processing, banking integrations, reconciliation workflows, secure API development, and high-volume financial systems. I have worked with REST/SOAP banking APIs, payment gateways, virtual ledger systems, transaction idempotency, settlement processes, KYC/AML workflows, and audit-compliant architectures. My Oracle experience includes PL/SQL development, performance optimization, transaction consistency, indexing, partitioning, and handling concurrent financial operations at scale. A key challenge I solved involved preventing duplicate transactions across distributed services by implementing idempotency keys, event tracking, and reconciliation mechanisms, significantly improving transaction reliability. I can contribute 30–40 hours per week, provide well-documented code, API documentation, migration scripts, automated tests, and deployment guides. I communicate effectively in English and am comfortable collaborating with distributed teams throughout the project lifecycle. I would welcome the opportunity to discuss your platform, banking integrations, and technical requirements in more detail. Best regards

@toqeer74

Designing and deploying Spring Boot microservices for a high-transaction financial system presents unique challenges, especially in terms of scalability and data consistency. With extensive experience building robust eWallet solutions and integrating seamlessly with banking systems via REST APIs, I have successfully handled complex workflows including KYC/AML checks and transaction management. My hands-on expertise with Oracle Database ensures that issues like locking and concurrency are managed effectively in high-volume scenarios. The initial deliverable can be ready within 180 days. Should we do a quick trial task so you can see the quality first-hand?

@robertc079

Hello, With over a decade of experience under my belt, I am the perfect fit for your Senior Backend Developer position. I have successfully deployed numerous eWallet systems and integrated countless times with core banking systems. This means that I have hands-on familiarity with bank validations, balance checks, fund transfers, and building and maintaining eWallet systems; all within the Fintech space. In addition to this deep industry experience, I possess unparalleled skills in building Spring Boot microservices (including service discovery, API gateway, circuit breakers), working with Oracle Database (PL/SQL and complex joins), implementing Fintech-specific workflows (KYC/AML checks, dispute handling) among other skills you need. Pairing these competencies with my awareness of transaction and data encryption best practices essential for complex transactional system like yours makes me an almost perfect fit for your project. Let's talk more about how I can tackle your project's specifics such as double-entry accounting, reconciliation, reporting or ensuring PCI-DSS compliance/xhtmlj while working within timelines and offering good value for your budget. The value I'll bring to your project will extend beyond just delivering well-commented source code but also encompass guided deployment procedures, comprehensive test suites and necessary documentation to ensure a smoother handover process once the contract is concluded. Choose m Thanks!

@jacobl78

Hello, When it comes to specialized tasks such as working on your mission-critical Fintech platform, experience plays a crucial role in ensuring efficiency and performance. As a full-stack developer with over 8 years of hands-on experience, especially in Fintech environments, I am confident that my expertise would be a valuable asset for your project. This is because I have worked extensively on platforms similar to yours, including developing e-wallet systems and integrating with core banking systems. For example, I successfully integrated payment gateways with various banks while ensuring account validation, secure data transfer, balance checks, and secure fund transfers. This hands-on familiarity with bank integrations will allow me to seamlessly integrate your platform with multiple banks as required by your project description. Moreover, my solid background working with Oracle Database using PL/SQL will help in managing high-volume transactions seamlessly and handling concurrency effectively. Additionally, my understanding of financial development workflows esp., double-entry accounting, reconciliation, reporting, and settlement cycles, will be useful in implementing Fintech-specific workflows like KYC/AML checks or dispute handling. In conclusion, my deep-set knowledge and skills make me the right fit for this job. Let's build a robust, efficient and highly secure platform that your users can rely on! Thanks!

@mayr81

Hello, I’m a senior Spring Boot backend developer with 5+ years in fintech, including eWallets, payment processing, bank integrations, and high-volume transaction platforms for anonymized wallet, lending, and payments apps. I have integrated REST, SOAP, and file-based flows with banks and gateways such as Stripe, PayPal, Adyen, Plaid-style account validation, and regional core banking APIs. My Oracle experience includes PL/SQL, indexing, partitioning, isolation-level handling, reconciliation queries, and protecting financial consistency under concurrent wallet operations. For your platform, I can build secure Spring Boot microservices with idempotent transaction APIs, double-entry ledger logic, OAuth2/JWT security, audit logging, Swagger docs, database migrations, and integration tests. One challenge I solved was duplicate fund-transfer execution during bank retry callbacks by adding idempotency keys, ledger state locks, and reconciliation alerts across services. Do you already have existing wallet/bank services to extend, or will these microservices be built from scratch? Best regards!