Denis Yurchak
I build products and write on X.
Things I've Built
These sites make money while I sleep until 10 AM.
eSIMPal
LiveeSIM for nomads in 150+ countries: unlimited hotspot, add unlimited countries without reinstalling, automatic country changes when crossing borders. Interface so simple, your grandma will get data to swipe grandpas on Turkish Tinder in 2 minutes.
Yadaphone
LiveSkype closed in 2025. I built an alternative in 2 days and grew it to 10,000 users in 6 months. People use it to call banks and government services abroad, businesses use it to call their leads, and I use it to call the accountant (he still doesn't respond).
Pro-AC Wear Shop
LiveMerch shop with pro air-conditioning designs, for people who believe summer should be survivable. Started after my AC quote in a Xinhua heatwave story went around the world.
Free Anki right in the browser: real SM-2 spaced repetition, ready decks for Chinese Hanzi and Japanese Kana, and import of any .apkg deck, parsed and stored entirely on the user's device. No account needed.
Lingobrew
LiveDesigned and built a B2C platform for language learning. Scaled from 0 to 1000 monthly active users. The platform handles aggregation from 50 RSS news feeds in 10 different languages with translations, audio generation and AI-powered content sorting.
PhotoshootPro
LiveI cloned PhotoAI, translated it to German, translated it back to English, and started marketing. Then it made my first internet $. Most people used it to generate nudes.
Professional Experience
Things I did before making internet $.
Consultant Software Engineer
Self-employed
- Helped 5 VC-backed scale-ups on various greenfield projects
- Integrated 6sense API and developed user-facing dashboards for web analytics
- Built backend systems using Go and NodeJS
- Developed frontend applications with React, NextJS, and TypeScript
- Implemented data analytics using BigQuery and AWS
- Utilized Kafka for message broker functionality
Senior Software Engineer
- Led development of a phone-related product serving 100,000+ customers
- Designed and launched a company-wide service for phone number procurement
- Implemented hexagonal architecture and DDD principles
- Deployed using Github Actions, Kubernetes and ArgoCD
- Mentored team members in Go development practices
Senior Software Engineer
- Developed an efficient system for communication and decision-making regarding new features
- Individually developed a web platform for coaching digital creators
- Created a web frontend using React and TypeScript
- Built the backend with Go
- Implemented an internal credit-based payment system
- Enabled user chat functionality using WebSockets
- Integrated video call capabilities using WebRTC
Software Engineer
- Developed high-load RESTful APIs for fiscalization using Go and TypeScript
- Implemented RabbitMQ messaging system
- Managed application-level database transactions across services
- Secured k8s secrets using SOPS and flux
Media Appearances
Interviews, features, and stories about my entrepreneurial journey.
YouTube
Starter Story Interview
How I built a Skype alternative and grew it to 4500+ paying customers and 14k MRR in 6 months
View VideoYouTube
The Founder's Gambit Interview
He Built 15 Failed Products, And Now Makes $17K/Month
View Videobrutkasten
Featured in brutkasten, leading Austrian startup magazine
Ten Times Failed and Burned Out - Now Viral and Profitable with Skype Alternative
View ArticleWiener Wirtschaft
Featured in Wiener Wirtschaft, Austrian business magazine
Browser-based telephony from Vienna. Denis Iurchak developed Yadaphone out of personal need as a Voice over IP service; this year an eSIM card solution followed.
View ArticleHolod
Featured in Holod, independent Russian media
A Russian clones Skypeand gets rich
View ArticleCaptain Works
Featured in Captain Works, indie builders community
$17K/month after one year: a case study on launching a Skype alternative
View ArticleBaza Education
Featured in Baza Education, startup education platform
How a developer launched a $14K/mo SaaS based on a single feature from the discontinued Skype
View ArticleLatest Articles
Thoughts and insights on software engineering, system design, and technology.
Concurrency in Go: Goroutines
Don't confuse OS threads and goroutines
Deploy RabbitMQ with Kubernetes and Persistent Volumes
Message broker deployment guide
Use ChatGPT as a developer
Finish work that takes days in 30 minutes
Become a Full-Stack Developer in 2023
In 5 months, studying 5 hours a day
Set up a Google Chat Alert with Google Cloud
Monitor your apps with chat notifications
Let's Work Together
I'm always open to discussing new projects, opportunities, or partnerships. Let's build something amazing together.
Ready to start a project?
Whether you need a technical consultation, want to collaborate on a project, or just want to say hello, I'd love to hear from you.