About Ahmad Hussain
I'm a Berlin-based Senior Software Engineer with 8+ years of experience building scalable backend systems and fintech products across Germany and Europe. Currently working in the payments industry at Payabl (Frankfurt), I specialise in Node.js, NestJS, PHP (Symfony), PostgreSQL, Redis, Elasticsearch, and AWS.
I've worked as a Founding Engineer at a Berlin startup, led engineering teams at Nord Security, and built production systems at Flixbus and Anwalt.de. I'm comfortable owning projects end-to-end — from architecture decisions to deployment.
As a freelancer, I can help you with:
Backend API development (REST, WebSocket)
Fintech integrations (payment gateways, POS providers, PCI DSS)
Cloud infrastructure on AWS
Code reviews, technical audits, and legacy refactoring
Team mentoring and interim tech lead support
I work with startups and Mittelstand companies that need senior-level execution without the overhead of a full-time hire. Let's build something solid.
English
Native or bilingual
German
Conversational
Can work on-site
Berlin (up to 50km)
Experience
- Payabl.Senior Software EngineerDIGITAL AND ITJuly 2024 - Today (1 year and 11 months)Frankfurt, Germany• ● Developed key fintech features, including merchant onboarding and payment processing, using Node.js, NestJS, and PHP.• ● Built custom fee structures for acquiring and integrating POS providers like Silverflow and Omnipay via RESTful APIs and WebSocket.• ● Worked on on-premises infrastructure, ensuring scalability, security, and PCI DSS compliance.• ● Collaborated with cross-functional teams to design and deliver scalable fintech solutions.
- Gomoon Gmbh,Founding EngineerDIGITAL AND ITJuly 2021 - April 2024 (2 years and 9 months)Berlin, Germany• ● Developed and launched MVP using Node.js, NestJS, React, and PHP.• ● Managed cloud infrastructure on AWS, ensuring scalability and security compliance.• ● Led product vision and transitioned from offshore to in-house tech team leadership.• ● Integrated secure payment and banking APIs through RESTful API and WebSocket.• ● Led a three-person tech team, focusing on strategic technology advancements.Provided mentorship and support to junior engineers.
- Nord Security,Senior EngineerDIGITAL AND ITMarch 2022 - March 2023 (1 year)Berlin, Germany• ● Led a team of 4 and planned a cluster migration project.• ● Define a team process that includes communication, collaboration, and development.• ● I cultivated partnerships between engineering, product, and UX personnel to create holistically designed final products.• ● Worked closely with management teams to plan, develop, and execute technical strategies aligned to the client's vision.• ● Performed code reviews, provided constructive feedback, and mentored junior team members.• ● I regularly gave team members individual performance metrics and observations.• ● I worked with TypeScript, PHP (using the Symfony framework), Golang, and Node.js. also with Redis and PostgreSQL databases, and deploying applications on AWS.
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Education
- Bachelor of ScienceIqra University2015Bachelor of Science
Certifications
- Scrum MasterScrum.org2017