Senior Software Engineer - Java

About ZYSYGY

ZYSYGY is building Germany's zero-fee payment network. Merchants pay zero transaction fees. We route payments directly over SEPA Instant, bypassing Visa, Mastercard, and the entire card network chain. No hardware. No card reader. Just a phone.

We are building the first company to combine a fully software-based merchant POS with a consumer super-app for everyday financial life: payments, transport, utilities, government services, all in one place. Think what UPI did for India. We are doing it for Germany, from the ground up, on banking rails.

Role Overview

You will join the core engineering team as a founding engineer. You will own the backend payment engine end to end: transaction flows, wallet management, SEPA Instant settlement, KYB/KYC integration, recurring mandates, refund logic, and the compliance export layer (DATEV, Kassenbuch, GoBD, fiskaltrust). On mobile, you will contribute to the React Native consumer and merchant apps alongside our mobile engineer.

You will own what you build from development through deployment, monitoring, and production reliability. The architecture decisions you make in the first six months will run in production for years.

What you will do

Design and build the backend payment engine: transaction flows, wallet management, SEPA Instant settlement, offline payment authorization, and recurring mandate billing.

Own KYB/KYC integration and the compliance export layer: DATEV, Kassenbuch, GoBD, and fiskaltrust for KassenSichV.

Build REST APIs for financial-grade reliability and high-throughput transaction processing, including full R-transaction handling and reconciliation pipelines.

Contribute to the React Native consumer and merchant mobile apps alongside our mobile engineer.

Own the full lifecycle of what you build, from development through deployment, monitoring, and continuous improvement.

Integrate AI tooling into your development workflow as a matter of course: code generation, automated testing, and intelligent review.

Who you are

Meaningful hands-on experience building payment systems, fintech infrastructure, or financial APIs.

You have designed a ledger. You understand double-entry bookkeeping, immutable transaction records, and why you never update a financial row.

You have solved the partial failure. Money left one wallet and did not arrive in the other. You know how to detect it, resolve it, and make sure it does not happen again.

You understand idempotency at a design level. You have built systems that survive client retries, duplicate webhooks, and network drops without double-charging anyone.

You have built or reasoned about reconciliation: detecting discrepancies between your internal ledger and an external settlement file, and resolving them reliably at scale.

You understand KYC and KYB state machines, what happens when verification status changes mid-transaction, and what a regulator expects from your audit trail.

You are comfortable with SQL databases and own the full lifecycle of your code from development through deployment.

You can communicate technical decisions clearly to non-technical stakeholders. At this stage of the company, that matters.

You are a continuous learner. Payments infrastructure is a deep domain and you treat it that way.

You are comfortable with ambiguity and early-stage risk. There is no playbook yet. You will help write it.

Strong academic background preferred. Demonstrated engineering ability matters more than institution.

Relocation

Relocation to Munich, Germany, is on the table for the right candidate, including visa support.

Connect with the Founder

You can also connect with me on LinkedIn at www.linkedin.com/in/shabbir-maimoon

Position = Java Developer

We are looking forward to hire a committed Java Developer with experience in building high performing, scalable, enterprise-grade applications. You will be part of our Engineering team that works on mission-critical applications. You will be managing Java/Java EE application development while providing expertise in the full software development lifecycle, from concept and design to testing.

You are required to:

Contributing in all phases of the development lifecycle.

Write well designed, testable & efficient code.

Ensure designs are in compliance with specifications.

Prepare and produce releases of software components.

Support continuous improvement by investigating alternatives and technologies and presenting these for architectural review.

Technical Skills required

Java, Springboot, Microservices, Data structures & Algorithms, MySQL, NoSQL, Mongodb and Hibernate.

OUR CURRENT STACK

Backend: Spring (JAVA), Laravel (PHP), MySQL, NoSQL, NGINX Plus.

Frontend: Angular 5+ Ngrx/store 5

Infrastructure: Google cloud platform (App engine, CloudSQL, BigQuery, PubSub, Firebase Hosting), Scrapy Cloud, Pusher.io (websockets), Getstream.io, Filestack, Postmark app, AS2 Gateway, Google Cloud Endpoints Framework, MongoDB, Algolia, Memcache

Tools: Gitlab, Postman app, JIRA. Wondering what your Responsibilities would be? Technical Skills required O

You are where our search ends, if you hold:

B. Tech/ M. Tech or corresponding degree

Experience in the same role of almost 1-6 years

Experience with connecting backend and frontend services.

Exposure to consuming data through different interfaces (Web API's/Socket/ REST/ RESTFUL/ JSON/ XML).

Proficiency in Data Structures and Algorithms.

Understanding of web markup, including HTML 5 CSS.

Understanding of client-side scripting and JavaScript frameworks.

Ability to write clean, reusable and well documented code.

Proficient understanding of code versioning tools, such as Git.

Knowledge of API authentication techniques (Token, JWT, OAuth2) - desirable but not mandatory. (Experience with API Design will be a plus)

Fair spoken and written English Flexibility - Things change around here. FAST!

Other Inter-personal skills like self-motivation, persistency, patience and eagerness to learn and work independently.

• Experience in either of these Relational DB’s MS SQL Server / PostgreSQL / AWS Aurora DB / MySQL / Oracle / NOSQL DBs (MongoDB / DynamoDB / DocumentDB) in an application development environment and eagerness to switch DB.
• Design database tables, views, indexes
• Write functions and procedures for Middle Tier Development Team
• Work with any front-end developers in completing the database modules end to end (hands-on experience in parsing of JSON & XML in Stored Procedures would be an added advantage).
• Query Optimization for performance improvement
• Design & develop SSIS Packages or any other Transformation tools for ETL

• Banking / Insurance / Retail domain would be a plus.
• Interaction with a client a plus

• Knowledge in a Cloud Platform (AWS / Azure)
• Knowledge on version control system (SVN / Git)
• Exposure to Quality and Process Management
• Knowledge in Agile Methodology

• Team building (attitude to train, work along, mentor juniors)
• Communication skills (all kinds)
• Quality consciousness
• Analytical acumen to all business requirement
• Think out-of-box for business solution

7+ years of experience with Design, development & architecture.

• Experience in software development with minimum 3 plus years of architecture experience.
• Experience in Core JAVA 8
• Experience in Java J2EE, Microservices
• Experience in Java - Spring, Java - SpringBoot, GCP , Hibernate,JDBC
• Experience in Multi-threading, Performance and Scaling is a plus
• Have used the RDBMS and NoSQL databases like MySQL/Oracle, MongoDB, Cassandra, Neo4J Risk for production ready software’s
• Cloud Native application design experience is a plus
• CICD – Release Pipeline experience
• Experience in application of principles of Architecture Design
• Experience building large scale, high performance distributed systems
• Strong understanding of modern development techniques and processes such as Dev Ops /Cloud
• Promoter of Agile/Scrum, TDD and CI/CD best practices
• Analyzes, designs, programs, debugs and modifies software enhancements and/or new products used in local, networked or Internet-related computer programs. (Code must be used in core version of applications available for sale commercially.)
• Interacts with Delivery managers and/or users to define system requirements and/or necessary modifications.
• Participates in software design meetings and analyzes user needs to determine technical requirements.
• Write technical specifications based on conceptual design and stated business requirements.
• Writes code, completes programming and performs testing and debugging of applications using current programming languages and technologies.
• Completes documentation and procedures for installation and maintenance.
• Trains and communicates with internal Client Training, Client Relationship and Sales teams on systems application.
• May be responsible for developing or executing project plans, budgets and schedules and for documenting work and results.
• May deliver informational and decision-seeking presentations to technical and business groups to internal and/or external audiences.

Job Summary:

We want a techie at heart. Someone who is happy and curious to work on all aspects of software development.

Reporting directly to the CTO, you will be responsible for feature design, development, and continuously optimizing our tech stack.

• We are looking for an experienced software engineer with at least 5 years of experience in a startup or product environment. Ideally you have been involved in all aspects of software development from requirements gathering to design, development, deployment and post-release support. We are looking for all-round technical maturity. Our tech stack is Angular, Spring boot and Django/Python.

Key Skills

Java

SpringBoot

PostgreSQL/MySQL

Git

AWS

REST api design

Experience integrating with external APIs

Good applied understanding of Object Oriented Programming

Good database modeling and SQL knowledge.

/React is a big plus.

Responsibilities and Duties

Build out features across the stack : backend, API design and integration, database optimization , microservices, plugins, queues etc

Fix bugs and write automated tests

Maintain and upgrade our Tech Stack

Translate requirements to design and write/present articulate software design.

JD:

As a Software Development Engineer at Amazon, you have industry-leading technical abilities and demonstrate breadth and depth of knowledge. You build software to deliver business impact, making smart technology choices. You work in a team and drive things forward.

Responsibilities:

• You solve problems at their root, stepping back to understand the broader context.
• You develop pragmatic solutions and build flexible systems that balance engineering complexity and timely delivery, creating business impact.
• You understand a broad range of data structures and algorithms and apply them to deliver high-performing applications.
• You recognise and use design patterns to solve business problems.
• You understand how operating systems work, perform and scale.

Requirements:

• You write high quality, maintainable, and robust code.
• You recognise and adopt best practices in software engineering: design, testing, version control, documentation, build, deployment, and operations.
• You have experience building scalable software systems that are high-performance, highly-available, highly transactional, low latency and massively distributed.
• Bachelors or Masters in Computer Science or relevant technical field.
• Experience in software development and full product life-cycle.
• Excellent programming skills in any object oriented programming languages - preferably Java, C/C++/C#, Perl, Python, or Ruby.
• Strong knowledge of data structures, algorithms, and designing for performance, scalability, and availability.
• Proficiency in SQL and data modeling.

Roles & Responsibilities:

• Excellent problem-solving & analytical skills & OO principles
• Solid understanding of the data structure & algorithms.
• Expert knowledge with any one of the Javascript Framework such as Node Js.
• Any additional experience with Java or python, GoLang would be nice to have.
• Experience working with SQL database like MySQL or PostgreSQL
• Experience working with NoSQL databases like mongoDB, couchbase would be nice to have
• Working experience with cache like redis, mem cached or elasticache would be nice to have
• Working experience with Message Queues would be a great advantage.
• Experience with deployment & AWS would be nice to have
• Ability to do in depth analysis or problem statement or use case & Build robust & scalable architecture
• Logging & monitoring of the production system in real time
• Lead a team of 2-4 team members & make sure team practices defined coding practices across the project. 

• Strong experience in Java Development
• Deep expertise and hands-on experience with Web Applications
• Expertise in Java, Spring Boot is an added advantage.
• Experience in Microservices
• Hands-on design experience with Web Services (REST, SOAP, etc ..).
• Strong grasp of security principles.

Nice to Have

• Spring Zuul
• Kafka
• cryptography and certificates

Abilities:

• Developer with  strong ability to develop web applications using Java
• Should be able to Code, design, and implement
• Maintain code integrity and organization