The Software House was brought in to rebuild eSky's booking platform backend, migrating from PHP Zend to Symfony to support the company's aggressive international expansion plans.

eSky's outdated backend couldn't keep up with their growth ambitions. Every new market took 2 months to launch, and the system struggled under the weight of millions of users searching through 1,030 airlines and 1.3M accommodation options.

eSky

eSky is a worldwide online travel agency present in 50 markets, providing booking services for 1,030 airlines and 1.3 million hotels and apartments. The platform serves as a comprehensive search engine where travelers can book flights, hotels, cars, and insurance in one place.

INDUSTRY

Travel & Transportation

COUNTRY

Poland

SERVICE PROVIDED

Platform modernization

Challenge

eSky started as a Polish booking platform with big international ambitions. As they expanded, each localized domain connected to a single PHP Zend booking engine that processed massive volumes of data - airline availability, hotel inventory, car rentals, and insurance options - all displayed in 18+ languages and currencies with 13 filter categories.

The problem? The system couldn't scale. Performance issues caused frustrated users to abandon bookings. Launching new markets took forever. The company hit a ceiling just as lucrative opportunities opened up.

An internal audit suggested the solution: PHP Symfony. But eSky lacked developers who mastered it.


Key challenges and requirements:

• Legacy system bottleneck: PHP Zend backend couldn't handle increasing user volumes

• Slow market expansion: 2-month timeline to launch each new country

• Performance degradation: System struggled under 180M+ annual visitors

• Talent gap: No in-house Symfony expertise to execute migration

• Zero downtime requirement: Migration needed to happen without service interruption

• Complex data processing: Real-time search across millions of travel options in multiple languages and currencies

• PCI DSS certification: Required for secure payment processing
  
  
  

Solution


The Software House filled eSky's talent gap in weeks, not months, with a team of 11-12 PHP developers who specialized in Symfony. We joined as one of the first partners supporting their migration from Zend Framework to Symfony - essentially acting as consultants with the expertise eSky needed.

Rather than attempting a risky "big bang" migration, we rebuilt the backend component by component over three years, ensuring stability throughout. Our developers taught eSky's internal team Symfony from the ground up, creating a unified team that could maintain the new system long-term.

The strategy focused on four core areas: transaction process, deals, hotels, and travel guide - with each rewrite unlocking new capabilities and markets.

eSky platform ready to serve milions of users

Process


Team Composition:

• 11-12 developers from The Software House

• Close collaboration with eSky's internal team

  
  

Technology Stack:

• Backend: PHP Symfony (migrated from Zend Framework)

• Frontend: JavaScript

• Architecture: BDD (Behavior-Driven Development) and DDD (Domain-Driven Development) approaches

• Infrastructure: Redis for caching to maintain high performance

• Testing: Automated tests using Behat and Selenium

The Zend to Symfony Migration

The entire backend built in Zend Framework required a complete rewrite. The Software House joined as one of the first partners supporting eSky in this migration - at a time when eSky had little Symfony experience.

Our developers were working with eSky's internal team hand in hand, enhancing their Symfony skills and ensuring they could maintain and develop the new system independently after the migration.

After our lead developer presented the migration plan, we began systematically rebuilding the platform's backend components in Symfony 2+, using BDD and DDD approaches for better code quality and maintainability.

Four Core Areas Rebuilt in Symfony

1. Transaction Process
We rebuilt the entire booking flow from scratch in Symfony: Quick Search Form (QSF), search results, pricing engine, and the multi-step booking form with passenger data collection. This covered both backend logic and frontend integration.

2. Deals
Developed parallel to the transaction process, this feature showed the best available offers in real-time. We built the search functionality, offer display, detailed pricing calendar, and price alert system - all in Symfony.

3. Hotels
This was the most critical migration. Rewriting the hotel booking system in Symfony was required to achieve PCI DSS certification. We created an intermediary layer between the legacy .NET application and our new Symfony backend, transforming SOAP responses into a modern REST API. The solution used Redis caching for high performance and integrated with TripAdvisor for hotel reviews.

4. Travel
Guide Our task was to rebuild static informational pages for travelers. This served as our entry point into the broader migration project.

Technical Migration Highlights

• Framework transition: Complete rewrite from Zend Framework to Symfony 2+ across all core platform components

• Knowledge transfer: Trained eSky's developers on Symfony fundamentals to ensure long-term maintainability

• Modern architecture: Implemented BDD and DDD approaches, replacing the monolithic Zend structure

• API modernization: Built REST API layer to replace legacy SOAP integration during the migration

• Frontend evolution: Migrated from JavaScript to TypeScript and Angular 2 alongside the backend changes

• Production rollout: Supported eSky through deploying the new Symfony system to production without downtime

• Security compliance: The Symfony migration enabled PCI DSS certification for secure payment processing

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Outcome

eSky cut market launch time by 77% - from 2 months to just 2 weeks - and earned 10 product innovation awards for the transformed platform.