Software Engineer -Senior Role

Wissen Technology is now hiring for a Java Developer - Bangalore with hands-on experience in Core Java, algorithms, data structures, multithreading and SQL. We are solving complex technical problems in the industry and need talented software engineers to join our mission and be a part of a global software development team. A brilliant opportunity to become a part of a highly motivated and expert team which has made a mark as a high-end technical consulting. 

Required Skills:

• Experience - 4+ years
• Experience in Core Java and Spring Boot.
• Extensive experience in developing enterprise-scale applications and systems. Should possess good architectural knowledge and be aware of enterprise application design patterns.
• Should have the ability to analyze, design, develop and test complex, low-latency client- facing applications.
• Good development experience with RDBMS.
• Good knowledge of multi-threading and high-performance server-side development.
• Basic working knowledge of Unix/Linux.
• Excellent problem solving and coding skills.
• Strong interpersonal, communication and analytical skills.
• Should have the ability to express their design ideas and thoughts.

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

Job Details

- Job Title: Senior Backend Engineer

- Industry: SAAS

- Function – Information Technology

- Experience Required: 5-8 years

- Working Days: 6 days a week, (5 days-in-office, Saturdays WFH)

- Employment Type: Full Time

- Job Location: Bangalore

- CTC Range: Best in Industry

Preferred Skills: AWS, NodeJS, RESTful APIs, NoSQL

Criteria

· Minimum 5+ years in backend engineering with strong system design expertise

· Experience building scalable systems from scratch

· Expert-level proficiency in Node.js

· Deep understanding of distributed systems

· Strong NoSQL design skills

· Hands-on AWS cloud experience

· Proven leadership and mentoring capability

· Preferred candidates from SAAS/Software/IT Services based startups or scaleup companies

Job Description

The Role:

What You’ll Build:

1. System Architecture & Design

● Architect highly scalable backend systems from the ground up

● Define technology choices: frameworks, databases, queues, caching layers

● Evaluate microservices vs monoliths based on product stage

● Design REST, GraphQL, and real-time WebSocket APIs

● Build event-driven systems for asynchronous processing

● Architect multi-tenant systems with strict data isolation

● Maintain architectural documentation and technical specs

2. Core Backend Services

● Build high-performance APIs for 3D content, XR experiences, analytics, and user interactions

● Create 3D asset processing pipelines for uploads, conversions, and optimization

● Develop distributed job workers for CPU/GPU-intensive tasks

● Build authentication/authorization systems (RBAC)

● Implement billing, subscription, and usage metering

● Build secure webhook systems and third-party integration APIs

● Create real-time collaboration features via WebSockets/SSE

3. Data Architecture & Databases

● Design scalable schemas for 3D metadata, XR sessions, and analytics

● Model complex product catalogs with variants and hierarchies

● Implement Redis-based caching strategies

● Build search and indexing systems (Elasticsearch/Algolia)

● Architect ETL pipelines and data warehouses

● Implement sharding, partitioning, and replication strategies

● Design backup, restore, and disaster recovery workflows

4. Scalability & Performance

● Build systems designed for 10x–100x traffic growth

● Implement load balancing, autoscaling, and distributed processing

● Optimize API response times and database performance

● Implement global CDN delivery for heavy 3D assets

● Build rate limiting, throttling, and backpressure mechanisms

● Optimize storage and retrieval of large 3D files

● Profile and improve CPU, memory, and network performance

5. Infrastructure & DevOps

● Architect AWS infrastructure (EC2, S3, Lambda, RDS, ElastiCache)

● Build CI/CD pipelines for automated deployments and rollbacks

● Use IaC tools (Terraform/CloudFormation) for infra provisioning

● Set up monitoring, logging, and alerting systems

● Use Docker + Kubernetes for container orchestration

● Implement security best practices for data, networks, and secrets

● Define disaster recovery and business continuity plans

6. Integration & APIs

● Build integrations with Shopify, WooCommerce, Magento

● Design webhook systems for real-time events

● Build SDKs, client libraries, and developer tools

● Integrate payment gateways (Stripe, Razorpay)

● Implement SSO and OAuth for enterprise customers

● Define API versioning and lifecycle/deprecation strategies

7. Data Processing & Analytics

● Build analytics pipelines for engagement, conversions, and XR performance

● Process high-volume event streams at scale

● Build data warehouses for BI and reporting

● Develop real-time dashboards and insights systems

● Implement analytics export pipelines and platform integrations

● Enable A/B testing and experimentation frameworks

● Build personalization and recommendation systems

Technical Stack:

1. Backend Languages & Frameworks 

●  Primary: Node.js (Express, NestJS), Python (FastAPI, Django)

●  Secondary: Go, Java/Kotlin (Spring)

●  APIs: REST, GraphQL, gRPC

2. Databases & Storage

● SQL: PostgreSQL, MySQL

● NoSQL: MongoDB, DynamoDB

● Caching: Redis, Memcached

● Search: Elasticsearch, Algolia

● Storage/CDN: AWS S3, CloudFront

● Queues: Kafka, RabbitMQ, AWS SQS

3. Cloud & Infrastructure: 

● Cloud: AWS (primary), GCP/Azure (nice to have)

● Compute: EC2, Lambda, ECS, EKS

● Infrastructure: Terraform, CloudFormation

● CI/CD: GitHub Actions, Jenkins, CircleCI

● Containers: Docker, Kubernetes

4. Monitoring & Operations 

● Monitoring: Datadog, New Relic, CloudWatch

● Logging: ELK Stack, CloudWatch Logs

● Error Tracking: Sentry, Rollbar

● APM tools

5. Security & Auth

● Auth: JWT, OAuth 2.0, SAML

● Secrets: AWS Secrets Manager, Vault

● Security: Encryption (at rest/in transit), TLS/SSL, IAM

What We’re Looking For:

1. Must-Haves

● 5+ years in backend engineering with strong system design expertise

● Experience building scalable systems from scratch

● Expert-level proficiency in at least one backend stack (Node, Python, Go, Java)

● Deep understanding of distributed systems and microservices

● Strong SQL/NoSQL design skills with performance optimization

● Hands-on AWS cloud experience

● Ability to write high-quality production code daily

● Experience building and scaling RESTful APIs

● Strong understanding of caching, sharding, horizontal scaling

● Solid security and best-practice implementation experience

● Proven leadership and mentoring capability

2. Highly Desirable

● Experience with large file processing (3D, video, images)

● Background in SaaS, multi-tenancy, or e-commerce

● Experience with real-time systems (WebSockets, streams)

● Knowledge of ML/AI infrastructure

● Experience with HA systems, DR planning

● Familiarity with GraphQL, gRPC, event-driven systems

● DevOps/infrastructure engineering background

● Experience with XR/AR/VR backend systems

● Open-source contributions or technical writing

● Prior senior technical leadership experience

Technical Challenges You’ll Solve:

● Designing large-scale 3D asset processing pipelines

● Serving XR content globally with ultra-low latency

● Scaling from thousands to millions of daily requests

● Efficiently handling CPU/GPU-heavy workloads

● Architecting multi-tenancy with complete data isolation

● Managing billions of analytics events at scale

● Building future-proof APIs with backward compatibility

Why company:

● Architectural Ownership: Build foundational systems from scratch

● Deep Technical Work: Solve distributed systems and scaling challenges

● Hands-On Impact: Design and code mission-critical infrastructure

● Diverse Problems: APIs, infra, data, ML, XR, asset processing

● Massive Scale Opportunity: Build systems for exponential growth

● Modern Stack and best practices

● Product Impact: Your architecture directly powers millions of users

● Leadership Opportunity: Shape engineering culture and direction

● Learning Environment: Stay at the forefront of backend engineering

● Backed by AWS, Microsoft, Google

Location & Work Culture:

● Location: Bengaluru

● Schedule: 6 days a week, (5 days-in-office, Saturdays WFH)

● Culture: Builder mindset, strong ownership, technical excellence

● Team: Small, highly skilled backend and infra team

● Resources: AWS credits, latest tooling, learning budget

As an engineer, you will help with the implementation, and launch of many key product features. You will get an opportunity to work on a wide range of technologies (including Spring, AWS Elastic Search, Lambda, ECS, Redis, Spark, Kafka etc.) and apply new technologies for solving problems. You will have an influence on defining product features, drive operational excellence, and spearhead the best practices that enable a quality product. You will get to work with skilled and motivated engineers who are already contributing to building high-scale and high-available systems.

If you are looking for an opportunity to work on leading technologies and would like to build product technology that can cater millions of customers inclined towards providing them the best experience, and relish large ownership and diverse technologies, join our team today!

What You'll Do:

• Creating detailed design, working on development and performing code reviews.
• Implementing validation and support activities in line with architecture requirements
• Help the team translate the business requirements into R&D tasks and manage the roadmap of the R&D tasks.
• Designing, building, and implementation of the product; participating in requirements elicitation, validation of architecture, creation and review of high and low level design, assigning and reviewing tasks for product implementation.
• Work closely with product managers, UX designers and end users and integrating software components into a fully functional system
• Ownership of product/feature end-to-end for all phases from the development to the production.
• Ensuring the developed features are scalable and highly available with no quality concerns.
• Work closely with senior engineers for refining the and implementation.
• Management and execution against project plans and delivery commitments.
• Assist directly and indirectly in the continual hiring and development of technical talent.
• Create and execute appropriate quality plans, project plans, test strategies and processes for development activities in concert with business and project management efforts.

The ideal candidate is a passionate engineer about delivering experiences that delight customers and creating solutions that are robust. He/she should be able to commit and own the deliveries end-to-end.

What You'll Need:

• A Bachelor's degree in Computer Science or related technical discipline.
• 2-3+ years of Software Development experience with proficiency in Java or equivalent object-oriented languages, coupled with design and SOA
• Fluency with Java, and Spring is good.
• Experience in JEE applications and frameworks like struts, spring, mybatis, maven, gradle
• Strong knowledge of Data Structures, Algorithms and CS fundamentals.
• Experience in at least one shell scripting language, SQL, SQL Server, PostgreSQL and data modeling skills
• Excellent analytical and reasoning skills
• Ability to learn new domains and deliver output
• Hands on Experience with the core AWS services
• Experience working with CI/CD tools (Jenkins, Spinnaker, Nexus, GitLab, TeamCity, GoCD, etc.)

• Expertise in at least one of the following:

    - Kafka, ZeroMQ, AWS SNS/SQS, or equivalent streaming technology

    - Distributed cache/in memory data grids like Redis, Hazelcast, Ignite, or Memcached

    - Distributed column store databases like Snowflake, Cassandra, or HBase

    - Spark, Flink, Beam, or equivalent streaming data processing frameworks

• Proficient with writing and reviewing Python and other object-oriented language(s) are a plus
• Experience building automations and CICD pipelines (integration, testing, deployment)
• Experience with Kubernetes would be a plus.
• Good understanding of working with distributed teams using Agile: Scrum, Kanban
• Strong interpersonal skills as well as excellent written and verbal communication skills

• Attention to detail and quality, and the ability to work well in and across teams

Responsibilities:

- Design, develop, and implement robust and efficient backend services using microservices architecture principles.

-  Write clean, maintainable, and well-documented code using C# and the .NET framework.

-  Develop and implement data access layers using Entity Framework.

-  Utilize Azure DevOps for version control, continuous integration, and continuous delivery (CI/CD) pipelines.

-  Design and manage databases on Azure SQL.

-  Perform code reviews and participate in pair programming to ensure code quality.

-  Troubleshoot and debug complex backend issues.

-  Optimize backend performance and scalability to ensure a smooth user experience.

-  Stay up-to-date with the latest advancements in backend technologies and cloud platforms.

-  Collaborate effectively with frontend developers, product managers, and other stakeholders.

-  Clearly communicate technical concepts to both technical and non-technical audiences.

Qualifications:

-  Strong understanding of microservices architecture principles and best practices.

-  In-depth knowledge of C# programming language and the .NET framework (ASP.NET MVC/Core, Web API).

-  Experience working with Entity Framework for data access.

-  Proficiency with Azure DevOps for CI/CD pipelines and version control (Git).

-  Experience with Azure SQL for database design and management.

-  Experience with unit testing and integration testing methodologies.

-  Excellent problem-solving and analytical skills.

-   Ability to work independently and as part of a team.

-   Strong written and verbal communication skills.

-   A passion for building high-quality, scalable, and secure software applications.

• To perform requirement analysis and oversee the implementation of architectures of project scope
• To provide customized reusable solutions of project, program or operational scope
• To develop high-quality and detailed designs
• To conduct unit testing using automated unit test frameworks and identify and address possible risk by conducting mitigation action planning
• Conducting configuration of your own work or from the team and assess the technical impact of multiple technologies/strategies
• Reviewing the work of other developers with feedback for improvement (if applicable)
• Using coding standards and best practices to ensure quality deliverables

Job Responsibilities:

Support, maintain, and enhance existing and new product functionality for trading software in a real-time, multi-threaded, multi-tier server architecture environment to create high and low level design for concurrent high throughput, low latency software architecture.

• Provide software development plans that meet future needs of clients and markets
• Evolve the new software platform and architecture by introducing new components and integrating them with existing ones
• Perform memory, cpu and resource management
• Analyze stack traces, memory profiles and production incident reports from traders and support teams
• Propose fixes, and enhancements to existing trading systems
• Adhere to release and sprint planning with the Quality Assurance Group and Project Management
• Work on a team building new solutions based on requirements and features
• Attend and participate in daily scrum meetings

Required Skills:

•  JavaScript and Python
• Multi-threaded browser and server applications
• Amazon Web Services (AWS)
• REST

We are looking for a Java backend developer who would be working on the bleeding edge of technologies. We work primarily with a fully reactive stack powered by Spring Webflux and Reactive MongoDb Repository in AWS. Our services follow both event based approaches as well as workflow based depending on the use case.

Responsibilities

• Understand why a particular design was chosen and code accordingly
• Will have to deliver clean bug free unit tested code with minimal guidance
• Strive for continuous improvement by refactoring and applying best practices
• Learn and adapt to new technologies as necessary.
• Capable of working in both client side and server side technologies

Requirements

• Must have a Bachelor’s degree in computer science or equivalent
• Must have 2-3 years experience as a software developer
• Must be proficient in Core Java and Spring/Springboot. Knowledge of Webflux is not mandatory.
• Must have developed RESTful services
• Should understand git

Added Bonus

• Experience working with microservices
• Experience in a NoSql solution like MongoDB
• Experience working with Python