Backend SDE 2 - Python / Go

🧠 Job Description: Senior Java Developer (8+ Years Experience)

Location: Mumbai, India

Employment Type: Full-time, Hybrid mode of working

Company: Wissen Technology

Website: www.wissen.com

🚀 About Wissen Technology

Wissen Technology is a specialized technology consulting firm delivering cutting-edge solutions to global leaders in Banking & Finance, Telecom, and Healthcare. Established in 2015 and part of the Wissen Group (founded in 2000), Wissen has scaled rapidly with impressive impact and recognition.

• 🌍 Offices in US, UK, India, Australia, Mexico, and Canada
• 👥 1700+ Wissen Technology professionals; part of a 4500-strong Wissen Group
• 🏆 Great Place to Work® Certified
• 🧠 Featured as a Top 20 AI/ML Vendor (CIO Insider, 2020)
• 📈 Achieved 400% revenue growth in 5 years (with zero external funding)
• 💼 Delivered $1B+ worth of projects to 50+ Fortune 500 companies

Learn more about our work and thought leadership:

📄 Articles by Wissen | 💼 LinkedIn

About the Role

We are seeking an experienced Senior Java Developer with 8+ years of hands-on expertise in building scalable, high-performance applications. The ideal candidate will have strong fundamentals in Java, OOPS, Multithreading, Spring concepts, and SQL, and will play a key role in designing, developing, and optimizing enterprise-grade solutions.

Key Responsibilities

• Design, develop, and maintain complex applications using Core Java and Spring frameworks
• Apply advanced Object-Oriented Programming (OOPS) principles to deliver clean, modular, and reusable code
• Implement and optimize multithreaded applications for high-performance systems
• Work with SQL databases for efficient data modeling, query optimization, and integration
• Collaborate with cross-functional teams to gather requirements and translate them into technical solutions
• Conduct code reviews, troubleshoot issues, and ensure adherence to best practices
• Mentor junior developers and contribute to technical knowledge sharing within the team
• Ensure application scalability, performance tuning, and security compliance

Required Skills & Qualifications

• Bachelor’s/Master’s degree in Computer Science, Engineering, or related field
• 8+ years of professional experience in Java development
• Strong expertise in Core Java, OOPS, and Multithreading
• Hands-on experience with Spring concepts (Spring Core, Spring MVC, Spring Boot preferred)
• Proficiency in SQL and database design (MySQL, Oracle, PostgreSQL, etc.)
• Solid understanding of software development life cycle (SDLC) and Agile methodologies
• Strong analytical, problem-solving, and communication skills

🌟 Why Wissen?

Join a company that combines start-up agility with enterprise stability. Work alongside some of the brightest minds from institutions like MIT, Wharton, IITs, IIMs, and NITs. Be part of mission-critical projects for Fortune 500 giants, and grow in a culture that invests in your future.

Experience: 5 TO 8

Location: MUMBAI

Wissen Technology is now hiring for a Java Developer - MUMBAI 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:

• Exp. - 5 TO 8 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 Us:

At Wissen Technology, we deliver niche, custom-built products that solve complex business challenges across industries worldwide.

Founded in 2015, our core philosophy is built around a strong product engineering mindset—ensuring every solution is architected and delivered right the first time. Our commitment to excellence translates into delivering 2X impact compared to traditional service providers. How do we achieve this? Through a combination of deep domain knowledge, cutting-edge technology expertise, and a relentless focus on quality. 

We don’t just meet expectations—we exceed them by ensuring faster time-to-market, reduced rework, and greater alignment with client objectives. We have a proven track record of building mission-critical systems across industries, including financial services, healthcare, retail, manufacturing, and more. 

Wissen stands apart through its unique delivery models. Our outcome-based projects ensure predictable costs and timelines, while our agile pods provide clients the flexibility to adapt to their evolving business needs. Whether it’s AI/ML for unstructured data processing, cloud enablement, or data engineering, Wissen leverages its thought leadership and technology prowess to drive superior business outcomes. Our success is powered by top-tier talent. Our proprietary Interview Ninja platform ensures we hire the best, building high-performing teams that deliver unmatched results. 

Today, Wissen Technology has a global footprint with 2200+ employees across offices in the US, UK, UAE, India, and Australia. Our mission is clear: to be the partner of choice for building world-class custom products that deliver exceptional impact—the first time, every time.

Strong Senior Backend Engineer profiles

Mandatory (Experience 1) – Must have 5+ years of hands-on Backend Engineering experience building scalable, production-grade systems

Mandatory (Experience 2) – Must have strong backend development experience using one or more frameworks (FastAPI / Django (Python), Spring (Java), Express (Node.js).

Mandatory (Experience 3) – Must have deep understanding of relevant libraries, tools, and best practices within the chosen backend framework

Mandatory (Experience 4) – Must have strong experience with databases, including SQL and NoSQL, along with efficient data modeling and performance optimization

Mandatory (Experience 5) – Must have experience designing, building, and maintaining APIs, services, and backend systems, including system design and clean code practices

Mandatory (Domain) – Experience with financial systems, billing platforms, or fintech applications is highly preferred (fintech background is a strong plus)

Mandatory (Company) – Must have worked in product companies / startups, preferably Series A to Series D

Mandatory (Education) – Candidates from Tier - 1 engineering institutes (IITs, BITS, are highly preferred)

Strong Senior Backend Engineer profiles

Mandatory (Experience 1) – Must have 5+ years of hands-on Backend Engineering experience building scalable, production-grade systems

Mandatory (Experience 2) – Must have strong backend development experience using one or more frameworks (FastAPI / Django (Python), Spring (Java), Express (Node.js).

Mandatory (Experience 3) – Must have deep understanding of relevant libraries, tools, and best practices within the chosen backend framework

Mandatory (Experience 4) – Must have strong experience with databases, including SQL and NoSQL, along with efficient data modeling and performance optimization

Mandatory (Experience 5) – Must have experience designing, building, and maintaining APIs, services, and backend systems, including system design and clean code practices

Mandatory (Domain) – Experience with financial systems, billing platforms, or fintech applications is highly preferred (fintech background is a strong plus)

Mandatory (Company) – Must have worked in product companies / startups, preferably Series A to Series D

Mandatory (Education) – Candidates from top engineering institutes (IITs, BITS, or equivalent Tier-1 colleges) are preferred

Position Overview

We are seeking a skilled Developer to join our engineering team. The ideal candidate will have strong expertise in Java and Python ecosystems, with hands-on experience in modern web technologies, messaging systems, and cloud-native development using Kubernetes.

Key Responsibilities

• Design, develop, and maintain scalable applications using Java and Spring Boot framework
• Build robust web services and APIs using Python and Flask framework
• Implement event-driven architectures using NATS messaging server
• Deploy, manage, and optimize applications in Kubernetes environments
• Develop microservices following best practices and design patterns
• Collaborate with cross-functional teams to deliver high-quality software solutions
• Write clean, maintainable code with comprehensive documentation
• Participate in code reviews and contribute to technical architecture decisions
• Troubleshoot and optimize application performance in containerized environments
• Implement CI/CD pipelines and follow DevOps best practices
•  
• Required Qualifications
• Bachelor's degree in Computer Science, Information Technology, or related field
• 4+ years of experience in software development
• Strong proficiency in Java with deep understanding of web technology stack
• Hands-on experience developing applications with Spring Boot framework
• Solid understanding of Python programming language with practical Flask framework experience
• Working knowledge of NATS server for messaging and streaming data
• Experience deploying and managing applications in Kubernetes
• Understanding of microservices architecture and RESTful API design
• Familiarity with containerization technologies (Docker)
• Experience with version control systems (Git)
•  
• Skills & Competencies
• Skills Java (Spring Boot, Spring Cloud, Spring Security)
•  
• Python (Flask, SQL Alchemy, REST APIs)
• NATS messaging patterns (pub/sub, request/reply, queue groups)
• Kubernetes (deployments, services, ingress, ConfigMaps, Secrets)
• Web technologies (HTTP, REST, WebSocket, gRPC)
• Container orchestration and management
• Soft Skills Problem-solving and analytical thinking
• Strong communication and collaboration
• Self-motivated with ability to work independently
• Attention to detail and code quality
• Continuous learning mindset
• Team player with mentoring capabilities

Job Opening: FreeSWITCH Developer

Location: Ecospace Business Park, Rajarhat, Newtown, Kolkata

Employment Type: Full-Time, Permanent

Shift: Day Shift

Experience: Minimum 4+ years in FreeSWITCH/VoIP Development

Responsibilities:

• Design, develop, deploy, troubleshoot, and maintain tools and services supporting our cloud telephony network.
• Customize FreeSWITCH for large-scale audio/video conferencing (1000–1500 concurrent calls).
• Expertise in SIP, RTP, RTCP, TURN, STUN, NAT, TLS.
• Hands-on experience with RTP Proxy and routed audio conferences.
• Understanding of SDP Protocol offer/answer mechanism.
• Work with load testing tools for FreeSWITCH audio conferences.
• Deploy and manage multiple FreeSWITCH instances using load balancers.
• Debug issues using packet captures (Wireshark/Ngrep).
• Collaborate with mobile/API teams for integration and support.
• Knowledge of codecs (PCMU, PCMA, G729, Opus) and open-source telephony technologies (FreeSWITCH, WebRTC).
• Familiarity with SIP servers (SER/OpenSER), proxy servers, SBC, SIPX is a plus.

Qualifications:

• Bachelor’s degree in Engineering (B.Tech/MCA).
• 4+ years of hands-on experience in FreeSWITCH development or related VoIP technologies.
• Strong knowledge of Linux environments and command-line tools.
• Basic to intermediate SQL knowledge.
• Proficiency in scripting (Bash, Python, Perl) for automation.
• Strong understanding of VoIP protocols (SIP, RTP), networking principles (TCP/IP, DNS, DHCP, routing protocols).
• Excellent troubleshooting skills with ability to resolve complex technical issues.
• Strong problem-solving, communication, and collaboration skills.

Industry Preference:

• Travel (Preferred)
• Any Industry (Required)

Requirements:

• Proficient in fundamental Software Design Principles, Data Structures, Algorithms, Problem Solving and Complexity Analysis.
• Proficient in programming languages like Python/Java/Javascript/Golang or similar.
• Strong understanding of professional software engineering practices & best practices for the full software development life cycle, including coding standards, code reviews, source control management, build processes, testing, and operations.
• Hands-on Experience with SQL/NoSQL databases such as Postgres, Mysql, MongoDB.
• Hands-on experience with GIT, CI/CD, REST APIs and Cloud ( AWS/ GCP/ Azure) will be preferred.
• Understanding of Microservice Architecture and System Design Principles is a plus.
• Self-driven, detail-oriented and Strong sense of ownership, urgency, and ability to deliver great work.
• Demonstrated expertise in developing, releasing and maintaining large scale software applications.

• Hands-on development and optimization of image enhancing algorithms for image processing using computational imaging
• Working with peer teams on researching and resolving complex software and system problems
• Analvze and optimize different methodologies to improve output of image processing
• Work closely with Quality Assurance teams to refine algorithms for optimal system performance
• Support products from the early development and prototyping phases through to production
• Developing functional specifications per customer requirements
• Good understanding of image processing techniques such as edge detection skills, image alignment, removing noise, image segmentation, correction/modification, compression, and image reconstruction

1. Should be very strong Scala development(Coding)
2. With Any combination of Java/Python/Spark/Bigdata
3. 3+ years experience in Core Java/Scala with good understanding of multithreading
4. The candidate must be good with Computer Science fundamentals
5. Exposure to python/perl and Unix / K-Shell scripting
6. Code management tools such as Git/Perforce.
7. Experience with large batch-oriented systems 
8. DB2/Sybase or any RDBMS
9. Prior experience with financial products, particularly OTC Derivatives
10. Exposure to counterparty risk, margining, collateral or confirmation systems