René Klačan

I'm René Klačan and I love building software.

I am a husband, father of two, and a T-shaped software engineer with experience in designing and working on large-scale systems.

I'm co-founder and CTO of FirstLook.gg, a platform that helps game studios grow and manage their player communities, from early playtests through launch and beyond. We also build Creators.gg, connecting content creators with game studios and campaigns, and Player.gg, where players discover games and join playtests. FirstLook was acquired by Pragma in December 2024, and I now work on it full-time.

Previously, I was CTO at FetLife, a kinky social network with more than 1M daily active users and one of the largest Rails applications in the world.

I also co-founded AoE4 World with Robert van Hoesel. It's the largest community website for Age of Empires IV.

During my spare time, I love to be active, currently mainly lifting weights and running. I also enjoy cycling, hiking, climbing, yoga, games, and chess.

While I have plenty of experience with frontend and infrastructure, my biggest passion is backend development, systems architecture, and performance optimization throughout the whole stack. In other words, I love building scalable, performant, reliable, and cost-effective systems.

I have experience managing small teams but it is something I don't enjoy nor am I exceptionally good at, so I only want to focus on what I love the most - building great software.

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Experience

Co-founder & CTO at FirstLook.gg

Feb 2024 - Present

FirstLook.gg helps game studios build and manage relationships with players before and after launch. It brings player data, playtesting, key distribution, community tools, surveys and creator programs together. We also build Creators.gg, where content creators find games and paid campaigns, and Player.gg, where players discover games, join playtests and find rewards. FirstLook was acquired by Pragma in December 2024.

Backstory: We first built tools to help Frost Giant Studios onboard thousands of playtesters. When other studios asked for similar tools, we turned them into FirstLook.
Team: 40–50 people
Tech Stack: Typescript (Astro, Solid), Rust, PostgreSQL, Redis, OpenTelemetry, Docker, Tailwind

CTO at FetLife

Sep 2015 - Nov 2024

FetLife is a kinky social network for the BDSM, Fetish & Kinky community. Fetlife's mission is to help people feel comfortable with who they are sexually.

Key points:
  • Joined as Senior Engineer, became Engineering Team Lead in Apr 2016 and later got promoted to CTO in Aug 2016.
  • Managed small remote team.
  • Continuously collaborated with CEO on making sure technical vision is aligned with company vision.
  • Responsible for infrastructure & application architecture and hands-on development of the entire platform.
  • Actively participated in hiring.
  • Since I joined the traffic grew more than 20x and we managed to keep average response time under 200ms.
  • Led migration from bare-metal servers to Google Cloud Platform.
  • Performance optimization throughout the whole stack.
  • Designed and implemented iterations of user recommendations service using Python and later Rust.
  • Designed, implemented, and evolved activity feed backend (initially build in Ruby on top of Redis, later in Rust on top of ScyllaDB).
Team: 10-20 employees
Scale: 1M+ daily active users & 3B+ requests per day
Tech Stack: Ruby, Javascript/Typescript (Vue), Rust, Go, GCP, Kubernetes, MySQL, PostgreSQL, Redis, Elasticsearch, ScyllaDB, BigQuery, Terraform

Co-founder of AoE4 World

Dec 2021 - Present

AoE4 World is a community website for Age of Empires 4 game. Since its launch, it has become the most popular Age of Empires 4 community website for players and it's also the backbone of most community developed tools through its API.

Backstory: What I love even more than playing games is programming so after playing AoE4 for a while after the release I noticed the lack of any site analyzing the game data like civ win/pick rates so I decided to build one. After building a prototype over the weekend, I released it on Reddit and it immediately got some love from community which motivated me to keep working on it.
Key points:
  • Co-founded AoE4 World with Robert van Hoesel, starting as a game statistics website.
  • We grew site to become the main hub for all AoE4 players.
  • Because of lack of public APIs I reverse-engineered game's internal API calls.
  • Reverse-engineered game's internal game summary format and wrote a parser to extract interesting game info including build orders (not even available in the game).
  • Implemented a REST API to serve other community developers (used by the most popular Twitch overlay).
  • Worked with tournament organizers to provide exclusive statistics.
  • Deployed and managed infrastructure on GCP.
Team: 2 core developers & 1 active contributor
Scale: 115k users per month & 40M requests per month
Tech Stack: Ruby, Typescript (Vue, Solid), C#, Python, GCP, Kubernetes, PostgreSQL, Redis, Terraform, Tailwind

Founder of Korektor

Aug 2017 - Present

Korektor is a grammar corrector for Slovak language and with its userbase it's currently the most popular service of its kind in Slovakia.

Backstory: I started working on this project to help my wife who is a dyslexic, as I saw her struggling on daily basis I wanted to help her.
Key points:
  • Designed and implemented a statistical and rule based corrector for Slovak language in Rust.
  • Built document editor with spellcheck and grammar check functionality using React.
  • Built a Chrome extension and Google Docs plugin.
  • Deployed and managed infrastructure on GCP.
Team: Just me
Scale: 30k users per month
Tech Stack: Ruby, Rust, Javascript (React), GCP, Kubernetes, PostgreSQL, Redis

Co-Founder of Stormgate World

May 2023 - Mar 2024

Stormgate World is a community website for Stormgate game which currently functions as an aggregator for game related content.

Key points:
  • Aggregation of user-generated content across various platforms.
  • Optimized for fast loading times and user experience.
Team: 2 core developers
Scale: 5k users per month
Tech Stack: Typescript (Astro, Solid), Rust, Cloudflare, PostgreSQL, Redis, Tailwind

Favourite Literature