Senior Full Stack Software Engineer

Job description

Overview

Join Callbi — South Africa’s top‑performing, rapidly scaling interaction analytics platform.

We help enterprises turn conversations into insight using best‑in‑class engineering, strong security, and increasingly, practical AI.

We move quickly without cutting corners, and we’re looking for a senior engineer who thrives in that blend of pace, rigour, and ownership.

The Opportunity

You’ll own end‑to‑end delivery across a modern, multi‑region SaaS stack: designing and building .NET Core services, shaping robust data models for both OLTP and OLAP, and shipping polished front‑end experiences in TypeScript.

You’ll work with AWS at scale (ECS/serverless/SQS), apply secure engineering practices from day one, and help us securely leverage LLMs where they deliver real customer value.

Our primary front‑end is Aurelia for its clean binding, use of web standards and convention‑over‑configuration model; strong React/Angular engineers ramp up quickly.

What You’ll Do

• Design and build resilient ASP.NET Core REST APIs with OpenAPI/Swagger that are a pleasure to consume.
  
  
• Model and optimise relational schemas for OLTP workloads and design/shape data for OLAP and analytics use‑cases.
  
  
• Build product features end‑to‑end across TypeScript + Aurelia (our primary FE; React/Angular experience transfers well) and .NET services.
  
  
• Architect, implement, and operate workloads on AWS (ECS Fargate, Lambda, API Gateway/ALB, SQS/SNS/EventBridge, S3, RDS/Aurora, IAM, VPC, CloudWatch) using AWS Well‑Architected principles.
  
  
• Contribute to containerisation and orchestration (Docker, Kubernetes), with a bias for maintainability and observability.
  
  
• Implement secure authentication and authorisation patterns (OIDC/OAuth2), and champion secure coding and OWASP Top 10 remediation.
  
  
• Instrument services with tracing/metrics/logging (OpenTelemetry/Grafana/CloudWatch), and drive performance improvements.
  
  
• Automate everything: CI/CD, infrastructure‑as‑code (preferably AWS CDK in C#), testing, quality gates.
  
  
• Collaborate closely with product/design, run thoughtful code reviews, and shepherd features from idea to production.
  
  
• Explore and apply LLMs and practical ML where they unlock real user value and operational leverage.
  
  

Our Tech (you don’t need all, but strong overlap is expected)

• Back‑end: C#/.NET 8+, ASP.NET Core, OpenAPI, EF Core
• Data: Strong SQL; modelling for OLTP & OLAP; caching/queuing patterns
• Cloud & Infra: AWS (ECS Fargate, Lambda, SQS/SNS/EventBridge, S3, RDS/Aurora, CloudFront, API Gateway/ALB, IAM, KMS, etc), IaC (AWS CDK — C# preferred), Docker, Kubernetes (EKS exposure a plus)
• Front‑end: TypeScript, Aurelia (primary); React/Angular welcome; modern tooling, testing libraries
• Security & Observability: OIDC/OAuth2, OWASP Top 10, OpenTelemetry, Prometheus/Grafana, CloudWatch
• AI/LLMs (nice to have): Bedrock/OpenAI/Anthropic/Alphabet/Meta, embeddings/vector search, prompt/response shaping, safety/guardrails

What You’ll Bring

Must‑haves

• 5+ years building production software, including ownership of significant backend services and customer‑facing front‑ends.
  
  
• Deep .NET Core experience; strong API design instincts; comfort with OpenAPI tooling.
  
  
• Expert SQL (query tuning, indexing, schema design) for OLTP and OLAP contexts.
  
  
• Real experience running on AWS at scale (serverless and containerised), and applying Well‑Architected practices.
  
  
• Hands‑on Kubernetes knowledge (you’ve deployed, debugged, and operated workloads).
  
  
• Production experience in TypeScript plus a modern FE framework; Aurelia ideal (React/Angular transfer well).
  
  
• Demonstrable secure coding habits; able to identify, prevent, and remediate OWASP Top 10 issues.
  
  
• Clear communication, product empathy, and a bias to action — you’re a self‑starter who ships.
  
  

Nice to haves

• OIDC/OAuth2 expertise (Auth code + PKCE, token lifecycles, scopes/claims, etc).
  
  
• Experience with event‑driven architectures (e.g., Kafka/Redpanda) and analytics pipelines.
  
  
• Practical use of LLMs in production workflows or developer tooling.
  
  
• Multi‑tenant SaaS patterns, privacy‑by‑design, and familiarity with POPIA/GDPR .
  
  

What Success Looks Like (first 90 days)

• Ship a meaningful feature across API + UI with solid tests, telemetry, and docs.
  
  
• Improve the performance of a high‑traffic query or service by an order of magnitude you can demonstrate.
  
  
• Challenge yourself to close a security gap, harden an auth flow or suggest a better way
• Propose and land a pragmatic LLM‑assisted improvement (dev‑workflow or product), with safety guardrails.
  
  

How We Work

• Hybrid : primarily remote; on‑site collaboration in Stellenbosch as needed.
  
  
• Autonomy with accountability : small, sharp team; high trust; strong engineering standards.
  
  
• Quality at speed : we move fast and maintain the bar through testing, reviews, and observability.
  
  

Hiring Process (what to expect)

• Intro - mutual fit, context.
  
  
• Practical exercise - A short take‑home assignment.
  
  
• Technical deep dive - Technical discussion.
  
  

Seniority level

• Mid-Senior level

Employment type

• Full-time

Job function

• Engineering and Information Technology

Required Skill Profession

Software Development