Senior Full Stack Engineer (JavaScript / TypeScript)

Senior Full Stack Engineer ( JavaScript/TypeScript )

Company -RASONIX

Location- Bengaluru, Karnataka

Work Mode - Full-time Work From Office (WFO)

Employment Type - Full-time

Experience- 6-9 years

Compensation - Best in industry, aligned with experience, ownership level, and technical depth

Role Mix - Approx. 80% hands-on engineering and 20% technical leadership

Shift - General day shift, MondayFriday; occasional overlap with US/client stakeholders as required

About the Role

RASONIX is looking for a hands-on Full Stack Engineer with deep JavaScript/TypeScript experience to own the architecture, development, performance, and delivery of enterprise-grade e-commerce, fintech, and internal operations systems. This is not a pure management role. The person should be comfortable writing production code, reviewing designs, debugging critical issues, mentoring developers, and making pragmatic architecture decisions in a fast-moving startup environment.

The role is ideal for someone who can work independently, convert ambiguous business problems into technical plans, and take end-to-end ownership with minimal supervision.

Key Responsibilities

Architecture and Technical Ownership

• Own end-to-end technical architecture for enterprise e-commerce, fintech, admin, operations, logistics, and finance modules.
• Make practical architecture decisions across modular monoliths, microservices, event-driven services, queues, caching, search, and databases.
• Design scalable, secure, maintainable systems that balance speed of delivery with long-term engineering quality.
• Create and maintain technical documentation, architecture notes, implementation plans, and release-level technical decisions.
• Identify bottlenecks and drive improvements in performance, scalability, observability, reliability, and cloud cost efficiency.

Hands-on Full Stack Development

• Build and maintain production-grade frontend applications using Next.js, React.js, TypeScript, SSR/SSG/ISR patterns, and modern state-management approaches.
• Build robust backend services, APIs, background jobs, schedulers, and integrations using Node.js, NestJS, and TypeScript.
• Work across customer-facing websites, fintech platforms, admin panels, internal dashboards, mobile-app APIs, and back-office workflows.
• Write clean, testable, maintainable code using SOLID principles, design patterns, and clean architecture practices.
• Integrate third-party services, payment gateways, cloud services, banking APIs, carrier/vendor APIs, and internal business systems where required.

Search, Data, Performance, and Caching

• Design and optimize OpenSearch/Elasticsearch indexes, search queries, filters, aggregations, and ranking strategies.
• Support vector search, semantic search, image search, and embedding-based retrieval pipelines where required.
• Design Redis or Memcached caching strategies for high-traffic filters, frequently accessed data, session/state needs, and performance-critical APIs.
• Optimize SQL and NoSQL schemas, indexing strategies, query performance, pagination, archival, and old-data retention approaches.
• Design reliable cron jobs, background processors, queues, retries, idempotent workflows, dead-letter handling, and asynchronous processing.

Delivery, Quality, and Operations

• Lead feature delivery from requirement analysis and estimation through development, testing, deployment, monitoring, and post-release stabilization.
• Work with Product, QA, DevOps, business stakeholders, and client stakeholders to clarify requirements and manage technical delivery.
• Contribute to sprint planning, effort estimation, risk identification, technical task breakdown, and release planning.
• Implement testing strategies including unit, integration, and end-to-end tests using tools such as Jest, Cypress, or Playwright.
• Troubleshoot production issues, perform root-cause analysis, and implement long-term scalable fixes rather than short-term patches only.

Technical Leadership

• Mentor junior and mid-level engineers through design discussions, code reviews, pair debugging, and engineering best practices.
• Set coding standards, review pull requests, improve development workflows, and maintain a high-quality engineering culture.
• Act as the technical owner for assigned modules and ensure delivery commitments are realistic, transparent, and quality-driven.
• Communicate clearly with non-technical stakeholders and convert business workflows into clear technical requirements.
• Take ownership in a fast-moving startup environment with minimal supervision, proactive planning, and strong execution discipline.

Required Technical Skills

(Area & Skills and Expectations)

Core Languages -

Expert JavaScript, TypeScript, Node.js; Python exposure for embeddings, AI, search, or automation pipelines is a plus.

Frontend -

Next.js, React.js, TypeScript, SSR, SSG, ISR, responsive UI, accessibility, frontend performance optimization, code splitting, and lazy loading.

Backend-

NestJS, Node.js, REST APIs, API design, authentication, authorization, background jobs, schedulers, WebSockets; GraphQL is preferred.

Databases-

PostgreSQL or MySQL, MongoDB or similar NoSQL databases, schema design, indexing, query optimization, transactions, archival, and high-availability awareness.

Search and Caching-

OpenSearch/Elasticsearch, Redis or Memcached, query tuning, filters, aggregations, caching strategy, invalidation patterns, and high-performance read paths.

Distributed Systems-

Queues, asynchronous processing, cron jobs, retries, idempotency, dead-letter queues, event-driven architecture, and brokers such as AWS SQS, Kafka, RabbitMQ, or ActiveMQ.

Cloud and DevOps-

AWS EC2, Lambda, SQS, OpenSearch, S3, CloudWatch, IAM, VPC; Docker, CI/CD pipelines, deployment automation, and monitoring.

Architecture-

System design, clean architecture, domain-driven design, modular monolith/microservices trade-offs, SOLID principles, design patterns, scalability, reliability, and maintainability.

Security-

OWASP Top 10, secure coding practices, JWT, OAuth2, RBAC, API security, rate limiting, encryption, data protection, auditability, and secure financial transaction handling.

Testing and Quality-

Unit, integration, and end-to-end testing with Jest, Cypress, Playwright, or similar frameworks; strong debugging and root-cause analysis skills.

Candidate Profile

• 6 to 9 years of professional software engineering experience, preferably with 2+ years in senior/lead ownership roles.
• Strong hands-on experience with JavaScript/TypeScript full-stack development, especially Next.js, React.js, Node.js, and NestJS.
• Proven experience building, scaling, and maintaining production-grade SaaS, e-commerce, fintech applications, ERP, payment platforms, internal operations, or enterprise workflow systems.
• Strong understanding of the complete software development lifecycle: requirements, documentation, estimation, design, coding, testing, deployment, monitoring, and support.
• Ability to independently own architecture, module design, technical planning, coding, reviews, releases, and production outcomes.
• Comfortable working in a startup environment with changing priorities, tight deadlines, high ownership expectations, and minimal supervision.
• Strong communication skills and the ability to work with business, product, QA, DevOps, and client stakeholders.

Good to Have

• Experience with enterprise e-commerce, marketplace, order management, inventory, vendor, warehouse, logistics, or delivery systems.
• Experience with finance/bookkeeping modules such as quotations, invoices, credit notes, debit notes, dispatch notes, reconciliation, and payment tracking.
• Experience building or maintaining Fintech applications, including payment processing, digital wallets, lending platforms, banking integrations, UPI, KYC/AML workflows, reconciliation, settlement, virtual accounts, payment orchestration, or financial transaction systems.
• Experience with AI-powered search, embeddings, vector databases, image search, RAG, OpenAI, Anthropic, Gemini, Amazon Bedrock, or similar AI services.
• Experience with payment gateway integrations, accounting system integrations, ERP integrations, third-party logistics/carrier integrations, or banking/payment service providers.
• Experience with Kubernetes, Terraform, CloudFormation, AWS certifications, TDD, open-source contributions, or performance engineering at scale.
• Exposure to Golang, Java, or Python services in addition to the primary TypeScript stack.

What Success Looks Like

First 30 Days

• Understand existing systems, business workflows, deployment process, codebase structure, search/data flows, and current pain points.

First 60 Days

• Own at least one meaningful feature or technical improvement end-to-end, improve development standards, and contribute to code reviews and release quality.

First 90 Days

• Drive measurable improvements in performance, search quality, caching, release predictability, documentation, and production reliability for assigned modules.

What We Look For

• High ownership mindset with the ability to work independently and drive outcomes without close supervision.
• Strong problem-solving ability in complex business domains involving many workflows, modules, integrations, and user roles.
• Strong engineering fundamentals with practical judgment and the ability to avoid unnecessary over-engineering.
• Ability to handle pressure, deadlines, sprint commitments, production issues, and shifting priorities maturely.
• Passion for quality, performance, security, scalability, clean code, and continuous improvement.
• Experience designing secure, high-volume financial transaction systems with a strong understanding of auditability, compliance, payment workflows, and data integrity is highly preferred.
• Leadership through execution: someone who can guide the team while still contributing heavily to code.

What We Offer

• Opportunity to own critical architecture and engineering decisions for enterprise-grade production systems.
• Hands-on exposure to high-performance e-commerce, fintech, AI-enabled, operations, logistics, and finance workflows.
• Direct impact on product scalability, performance, engineering standards, and technical direction.
• A high-ownership startup environment with room for leadership growth and meaningful technical influence.
• Best-in-industry compensation aligned with experience, ownership level, and technical depth.

How to Apply

Send your updated resume to hr@rasonix.com with the subject line: Application for Senior Full Stack Engineer ( JavaScript/TypeScript )- [Your Name] - Ref: [Reference Name if Any]