Senior Backend Engineer (.NET Core) for Digital Card Game Showdown

Remote, Hybrid
Prague
Full-time

Showdown, a digital card game inspired by poker is backed by MitonC and is alumni of prestigious accelerator MegaMafia.
We’re building the backend for a two-player online card game — a modular monolith where each module owns its own database and plays nicely with the others. It’s built to scale horizontally and run lean.

Stack: .NET Core 9, MVC Core, PostgreSQL 17, Newtonsoft.Json, Docker, DigitalOcean.

What you’ll do

Ship new features end-to-end: design, code, test, deploy.
Keep existing code clean and fast — change only what needs changing.
Own backend security: auth, validation, secrets, data protection, secure defaults.
Plan and implement scaling for high-load (stateless services, caching, pooling).
Integrate with external APIs (OAuth, webhooks, retries, signing, all the fun bits).
Write and maintain meaningful tests, keep CI green, review PRs for clarity and performance.
Diagnose production issues from logs/metrics and push fixes without drama.

Requirements

4+ years in C#/.NET with strong ASP.NET Core (Web/API) and MVC Core chops.
Confident in SQL and PostgreSQL: schema design, migrations, indexing, performance tuning.
Real experience with horizontal scaling, stateless architectures, pooling, caching (Redis).
Working knowledge of partitioning/sharding (Citus or app-level), replicas, zero-downtime deploys.
Deep sense of security hygiene: OWASP, token/session management, safe input/output, least privilege.
API integration patterns: OAuth2/PKCE, signed requests, retries, idempotency keys.
Docker and Linux familiarity; basic cloud ops (DigitalOcean is home turf).
Solid grasp of async/await, DI, REST, JSON, testing frameworks (xUnit/NUnit), Git discipline.

Bonus points if you’ve touched

Node.js (Express/Nest) for small tools or services.
Real-time game backends (SignalR/WebSockets).
Observability: logging, tracing, dashboards.
Performance tuning, caching, query optimization.
Citus, pg_partman, pgbouncer, Redis, autoscaling (DO/K8s), load testing tools (k6/Locust).
Integrations like Discord, email, analytics, auth providers, or tournament platforms.

What “scalable” means here

Stateless app nodes, externalized sessions/state, smooth rollouts.
Partitioned/sharded DBs, replicas, backpressure protection, safe migrations.
Caching, batching, pagination, idempotent APIs, sensible connection limits.
Simple autoscaling playbook and observability that actually helps.

What we Offer:

Hybrid (office in Karlín) cooperation with remote option;
You’ll work with a small team that values straightforward code, thoughtful design, and fast feedback loops. No BS meetings;
Learn from experienced entrepreneurs building their next venture;
Gain valuable Web3 gaming experience in a rapidly growing sector;
Work alongside founders who understand both competitive gaming and business strategy
Plenty of space for creativity and impact on the game early on.
Your input reaches decision-makers who've competed at world championship levels.
Compensation includes shares.

More about Showdown:

https://x.com/Showdown_TCG

https://www.showdown.game/