Principal Engineer (backend)

About the Role

As a Principal Backend Engineer at Sage, you will provide technical leadership in designing, developing, and delivering a high-quality SaaS solution that exceeds customer and business partner expectations. We are looking for someone with 10+ years of professional experience in backend engineering, who can bring technical depth, architectural vision, and leadership maturity to the team. Proficiency in English, written and verbal, is required.

We value humility and collaboration. We are looking for people who can work as part of a team, not in silos. We expect engineers to take ownership beyond just writing code, including tests, documentation, and long-term code quality.

Location: Bangalore, India. This is a hybrid role, three days per week in the office.

Required Skills

Core languages & runtime- Strong TypeScript (strict mode) and Node.js (v24+) for production services.

• Solid computer-science fundamentals: data structures, algorithms, concurrency, async I/O.

Backend frameworks & APIs- REST API design with Fastify (or Express/NestJS/Koa with willingness to learn Fastify).

• JSON Schema contract design and validation (AJV or equivalent); OpenAPI/Swagger.
• Understanding of API versioning, idempotency, pagination, and error-handling patterns.

Data & persistence- Relational databases MySQL and/or PostgreSQL: schema design, indexing, query tuning.

• Comfort with JSON-document modeling in a relational store and query compilation to SQL.
• SQL query builders (Knex or similar); parameterized queries and SQL-injection prevention.
• Caching with Redis.

Distributed systems & messaging- Event-driven / message-queue systems (AWS SQS, or Kafka/RabbitMQ/SNS equivalents): producer/consumer patterns, dead-letter queues, retries/backoff, and idempotency.

• Designing for at-least-once delivery and eventual consistency.

Cloud & platform- AWS services (SQS, EFS, S3, IAM, ECR) in a production context.

• Containerization with Docker; familiarity with Kubernetes deployments.

Security- OAuth2 / OIDC / JWT validation (RS256, JWKS), token propagation, and multi-issuer auth.

• Secure coding against the OWASP Top 10; multi-tenant isolation and row-level security.

Testing & quality- Unit, integration, and contract testing (Vitest/Jest or equivalent); test-driven mindset.

• Linters/formatters (Biome, ESLint/Prettier) and CI discipline.

Tooling & workflow- Git and pull-request workflows; monorepo experience (Nx) a plus.

• CI/CD (GitHub Actions or similar).

AI Tooling- Productive use of AI-assisted developer tooling (e.g. GitHub Copilot, Claude Code, Cursor) to accelerate day-to-day backend development.

• Integrating LLM / generative-AI capabilities into backend services (e.g. OpenAI, Anthropic, AWS Bedrock) via SDKs, streaming responses, and prompt/response validation.
• Familiarity with retrieval-augmented generation (RAG): embeddings, vector stores/search, and context assembly pipelines.

Nice to Have- Experience with MongoDB-like query languages or building a query compiler/DSL.

• KEDA / autoscaling on queue depth; Istio service mesh; Argo Rollouts canary deploys.
• GitOps (ArgoCD) and schema-driven DB migrations (Atlas or Liquibase/Flyway).
• Observability stacks: New Relic APM, Sumo Logic, Prometheus, Pino logging.
• Experience with git-like versioning / CRDT / operational-transform data models.
• Domain knowledge in finance, ERP, FP&A, or accounting systems.
• Building data-migration / reconciliation frameworks at scale.
• Experience building AI/ML-powered backend features such as forecasting, anomaly detection, or natural-language querying over financial data.

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Key Responsibilities

Responsibilities- Lead the design, development, and implementation of scalable, high-performance SaaS software

• Take technical ownership of products, systems, or services, ensuring robust and maintainable solutions.
• Provide guidance and mentorship to software engineers, fostering technical growth within the team and contribute to code reviews, architectural discussions, and technical design sessions.
• Collaborate with cross-functional teams, including product management, architecture, and quality assurance, to ensure successful product delivery.
• Identify and address performance bottlenecks, security vulnerabilities, and technical debt and act as a technical expert in solving complex software challenges.
• Drive continuous improvement in software development processes, tools, and methodologies.
• Stay current with emerging technologies and industry trends, applying them to improve product efficiency and quality.

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