Ruby on Rails Developer | Chennai

Role: Backend Developer

Experience: 3-6 years

Duration: 1–3 months

Tech Stack: .NET Core, MongoDB

Domain: Clinical/Healthcare (Preferred)

Responsibilities

• Develop and maintain REST APIs using .NET Core
• Design scalable backend services and microservices
• Implement data storage and retrieval using MongoDB
• Optimize database queries and application performance
• Integrate with external systems (APIs, FHIR etc.)
• Ensure data security and compliance (GxP/FDA preferred)
• Support debugging and production issue resolution

Required Skills

• Strong experience in .NET Core/ASP.NET Core
• Hands-on experience with MongoDB or NoSQL databases
• Experience in REST API development
• Knowledge of microservices architecture
• Familiarity with Git and CI/CD pipelines

Preferred

• Healthcare/Clinical Trial domain exposure
• Experience with Azure cloud deployments
• Understanding of FHIR or Healthcare Data Standards

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

Founding Engineer (Bangalore)

The problem:

Business enterprises overpay vendors - on every batch of invoices, on every month because the data that would catch lives in different systems. We are building an AI agent that processes invoices end-to-end, reasons across all the relevant sources, flags genuine discrepancies, and acts - without a human having to investigate each one.

What you will own

Everything engineering. Schema design to deployment to the 2am fix when something breaks in production. There is no tech lead above you. There is no platform team. There is the architecture, you, and the founders. Concretely, this means building:

• A multi-stage agentic pipeline that takes a vendor invoice and produces a structured decision - fully autonomous for clear cases, escalating to human review for genuinely ambiguous ones. We use LangGraph, but if you've built equivalent systems with Temporal, Prefect, or custom state machines with LLM orchestration, that works
• An LLM-powered extraction layer that handles real invoices - scanned PDFs, stamped documents, inconsistent layouts - and returns structured output
• A graph data model that connects invoices to various sources and can traverse those relationships to detect discrepancies
• ERP connectors, GST validation logic, and a write-back layer that closes the loop

What we need

• Strong Python. Async FastAPI, clean service boundaries, tests that actually catch bugs. You have shipped Python backends that handled real production load
• Solid Postgres. Complex queries, schema design, migrations without downtime, row-level security for multi-tenant data. pgvector is a plus - if not, you pick it up fast
• LLM API experience in production. You have called an LLM API for something that real users depended on. You know about structured output, retry logic, cost management, prompt versioning. A side project counts if it was genuinely deployed
• Comfort with graph data models. You understand when a graph is the right structure and when it is not. You do not need deep Neo4j production experience - you need to understand graph relationships conceptually and be willing to learn Cypher. It is a 2-day ramp for the right person
• Working knowledge of deployment. Deployed and operated production workloads on GCP. Cloud Run, Cloud SQL, Cloud Storage, Redis — you're comfortable across the stack. If you've done it on AWS, the translation isn't hard, but GCP is where we are
• You own things. Not "I contributed to" - you designed it, shipped it, and fixed it when it broke. That pattern needs to be visible in your history

Good to have, not mandatory

• Built an agentic pipeline with multiple stages
• Any fintech, P2P domain experience - even tangential
• Worked at a startup with under 20 people
• Has a GitHub, blog, or writeup that shows how you think about a hard technical problem

What you get

• The hardest engineering problem you would have worked on. This is not CRUD with an LLM bolted on
• Real ownership. First engineering hire. Your architectural decisions will be in this product five years from now
• Equity that matters. ESOP - Open to discussion. We are pre-seed - this is a bet, not a guarantee. We will not pretend otherwise
• No meetings tax. You work directly with the founders. The product is specified clearly. You know what you are building and why

Honest about stage: We do not have a production ready infra yet. We have a complete architecture specification and a working prototype. If you need the stability of an established engineering org, this is not the right moment. If you want to build something real from zero and own a meaningful piece of it, it is.

The founders

One of us has spent 20 years building revenue and operational engines at companies where there was no playbook - part of the pilot team that established the world's largest search company's direct sales operations in India, managed global operations for a global mobile advertising platform, scaled a B2C platform to become one of India’s leading edtech platforms and most recently worked on building an enterprise Agentic Voice AI platform. The other has spent 15 years taking AI from demo to production in domains where failure is expensive - voice, lending, and conversational systems across a Series D conversational AI company, a major telco, a Big 4, and a leading NBFC.

Two IIT/IIM alumni who have both watched AI work in enterprise, and know exactly what it takes to get it there. We are not building this product because it sounds interesting. We are building it because we have both sat across the table from CFOs who know they are losing margin and have no tool capable of doing anything about it.

• Developing and maintaining all server-side network components.
• Ensuring optimal performance of the central database and responsiveness to front-end requests.
• Collaborating with front-end developers on the integration of elements.
• Designing customer-facing UI and back-end services for various business processes.
• Developing high-performance applications by writing testable, reusable, and efficient code.
• Implementing effective security protocols, data protection measures, and storage solutions.
• Running diagnostic tests, repairing defects, and providing technical support.
• Documenting Node.js processes, including database schemas, as well as preparing reports.
• Recommending and implementing improvements to processes and technologies.
• Keeping informed of advancements in the field of Node.js development.

Node.js Developer Requirements:

• Bachelor's degree in computer science, information science, or similar.
• At least two years' experience as a Node.js developer.
• Extensive knowledge of JavaScript, web stacks, libraries, and frameworks.