Senior Backend Engineer — Build Scalable API & AI Services

Prosus; Amsterdam; On-site; EUR 90,000 - 130,000; Full time

Job summary

Prosus in Amsterdam is seeking a Senior Backend Engineer to own services end to end — from design and implementation to deployment, monitoring and pager duties. You will shape API contracts, database schemas and cost profiles, review backend PRs with care, and ensure a legible codebase while balancing reliability and cost.

You will focus on API Gateway (Go) and AI Agent Services (Python) with Postgres and Redis, and IaC via Terraform on GCP, delivering scalable, observable backend systems for a

Qualifications

• Backend development experience in Go/Python preferred.
• Experience designing and maintaining REST/WebSocket APIs.
• Familiarity with data modeling and database migrations.

Responsibilities

• Design, build and maintain REST and WebSocket endpoints serving the mobile app and WhatsApp surface
• Own domain models, repository interfaces, and database migrations
• Add new handlers and services as product features require
• Define and version shared API contracts (protobuf) consumed by the client
• Maintain authentication, authorisation and session handling
• Enforce rate limits, quotas and abuse protection
• Instrument services: structured logging, metrics, tracing and useful alerts
• Keep linters, formatting, and tests passing
• Extend the agent runtime: tool calling, orchestration, and third-party or portfolio API integrations
• Manage prompt and model configuration, versioning, and evaluation harnesses
• Control inference latency and cost through caching, batching, model routing and token budgets
• Build and maintain the memory and context layer on Postgres and Redis
• Handle asynchronous and long-running work: queues, retries, idempotency, dead-letter paths
• Postgres schema design, indexing, query performance and connection pooling
• Redis for caching, ephemeral state and pub/sub behind the real-time chat layer
• Maintain and extend infrastructure as code (Terraform on GCP): Cloud Run services, secrets, IAM
• Assist with deploys, rollbacks, and environment configuration
• Implement data retention, deletion and export paths required under GDPR and LGPD
• Support incident response and write up what happened afterwards
• Branch from dev, open PRs targeting dev, follow Conventional Commits
• Run pre-merge quality checks before pushing
• Write PRs with structured descriptions (why / what changed / how to test)
• Collaborate on the weekly release cadence
• Participate in code review (automated + peer)
• Harden the backend for scale: p95 latency, error rates, backpressure and graceful degradation
• Forecast capacity and cost across infrastructure and model inference
• Contribute to feature-flagged rollouts and zero-downtime migrations
• Improve observability so problems surface before users report them
• Help onboard future engineers to the backend codebase

Skills

Backend development

Tools

Go

Python

PostgreSQL

Redis

Terraform

GCP

Job description

Prosus in Amsterdam is seeking a Senior Backend Engineer to own services end to end — from design and implementation to deployment, monitoring and pager duties. You will shape API contracts, database schemas and cost profiles, review backend PRs with care, and ensure a legible codebase while balancing reliability and cost.

You will focus on API Gateway (Go) and AI Agent Services (Python) with Postgres and Redis, and IaC via Terraform on GCP, delivering scalable, observable backend systems for a