Back End Developer

Company Description Kaaliber aims to solve the problem of fragmented, expensive, and inefficient customer growth by bringing the entire marketing process into one AI-powered platform. Instead of managing multiple advertising channels, disconnected data, creative tools, and customer retention systems separately, Kaaliber unifies them into a single engine that helps businesses acquire high-value customers, automatically optimise budgets, continuously create fresh ads, understand what drives revenue, and retain existing users. By making real-time, data-driven decisions focused on actual business outcomes rather than just clicks and installs, Kaaliber aims to reduce wasted marketing spend, minimise reliance on multiple intermediaries, and help brands grow more efficiently and profitably across channels.

Key responsibilities

• Design and develop asynchronous APIs and services using Python and FastAPI with clear,

versioned contracts.

• Build secure authentication, authorization, tenant scoping and role-based access controls.

• Create PostgreSQL schemas, migrations, repositories and transactional workflows with attention

to data integrity.

• Integrate external APIs, OAuth services and webhooks with rate-limit handling, retries,

idempotency and reconciliation.

• Implement background jobs, scheduled processing and event-driven workflows using suitable

queues or streams.

• Apply strict input validation, consistent error handling and safe handling of secrets and sensitive

data.

• Add unit, integration and contract tests together with logs, metrics, traces and actionable alerts.

• Participate in design reviews, code reviews, performance tuning, incident response and

root-cause analysis.

• Maintain owned services through enhancements, scaling work and future product versions.

Must-have capabilities

• Advanced Python and practical FastAPI experience in production systems.

• Strong understanding of asynchronous programming, validation, dependency injection, API

design and background processing.

• PostgreSQL, SQL optimization, ORM usage, migrations and transaction management.

• Experience integrating external REST APIs using OAuth 2.0, webhooks, retries, rate limits and

idempotency.

• Testing experience with pytest and unit, integration, contract and mocked-provider tests.

• Secure engineering fundamentals including tenant isolation, least privilege, secrets hygiene and

input validation.

• Git, pull-request workflows, CI/CD and clear technical documentation.

Preferred experience

• Redis, Celery, Arq, Kafka, Redpanda or comparable asynchronous-processing technologies.

• Experience integrating AI services through structured, validated inputs and outputs.

• AWS, Docker, Kubernetes and observability with OpenTelemetry.

• High-volume data ingestion, analytics systems or complex workflow engines.