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Web & Mobile development

We work on world-class projects that change industries.
And sometimes people's lives.
That's just the way it is — we make excellent products.
Our technology stack:
  • Symfony
  • PHP
  • PostgreSQL
  • MySQL
  • MongoDB
  • Redis
  • RabbitMQ
  • React
  • Redux
  • PostCSS
  • Ruby
  • Rails
  • [BD] Big Data
  • [AI] Artifical Intelligence
  • [ML] Machine Learning
  • iOS
  • Android


Our in-depth understanding of finance, education and medicine allows customers from these industries to stand alongside our much-loved existing clients who have already been featured in leading publications around the world.

    financial technology

    education technology

    medical technology
They write about our projects:

Our projects

Write to us

We are ready to demonstrate why we are so good from the very first day.
Contact us any way that suits you best:

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About Us

We regard each project as our own. This is why our clients recommend 4xxi to their friends and business partners. We are simply incapable of not caring about what we do. We use modern development, management and testing standards.
Our own projects:


  • Head Office / 2-G Malaya Monetnaya St., St. Petersburg, 197101, Russia, LangenZipen Business Center, Office 403
  • Office / 7-A Tereshkova St., Saransk, Russia, Soyuz Business Center, Office 607