From Custom Code to Cutting-Edge: On The Beach Adopts WunderGraph Cosmo for GraphQL Federation

How On The Beach Handles 4B+ Monthly Clicks with WunderGraph Cosmo

4B+

Monthly clicks on On The Beach’s platform

Faster performance

Latency dropped by tens of milliseconds during peak traffic

1 month

Incremental migration from custom federation to Cosmo

Industry: Online Travel
Company Size: 1000+

Company Overview

On the Beach is a UK-based online travel retailer that specializes in affordable beach holidays, packaging together flights and accommodation for millions of customers each year across European and long-haul destinations. Operating as a digital-first business, it uses a scalable, cloud-based technology platform to dynamically combine inventory, manage customer bookings end to end, and optimize performance, which has enabled rapid growth since its launch in 2004 and public listing on the London Stock Exchange in 2015.

The Challenge

A Growing Monolith That Couldn’t Scale Safely

On The Beach began modernizing its platform with microservices and a universal GraphQL API. As more domains were added, including Flights, Hotels, and Transfers, it began to behave like a monolith. Changes required coordination across teams, bottlenecks formed around a central schema, and performance issues became harder to diagnose. With rising post-pandemic traffic, reliability became a primary concern.

The team introduced GraphQL Federation to relieve the pressure, but the tooling created new challenges.

We started building our own Federation Solution.

We ended up implementing a home baked solution utilizing Apollo Rover and schema stitching. It worked for a while, but as we grew, it became more and more difficult to maintain, and harder for teams to adopt. We decided to look for a better solution.
Stephen Wootten

Their homegrown approach worked for a time, but as the graph continued to grow, it was clear they needed a more stable foundation. On The Beach had outgrown custom federation and required a platform built for reliability, safety, and long-term scale.

The Solution

A Safer, More Observable Federation with WunderGraph Cosmo

On The Beach chose to adopt Cosmo for its open-source transparency and the strong partnership behind it.

Why On The Beach Chose Cosmo

• Open source transparency

The team could inspect the code, understand how federation worked, and trust the behavior of the system.

• Schema Registry and Studio

A centralized workflow for safe schema changes, versioning, validation, and clear domain ownership.

• Advanced Request Tracing

Deeper insight into query behavior made it easier to diagnose issues and improve performance.

• Event Driven Federated Subscriptions

Real-time booking confirmations and pricing updates that scale without adding operational overhead.

• Self-hosted router

Increased control over performance tuning, networking, and cost, aligned with their infrastructure needs.

• Incremental migration

Subgraphs were moved one at a time, allowing the team to modernize safely with support from WunderGraph engineers.

The Results

A More Reliable, Faster, and Safer GraphQL Platform

By moving to WunderGraph Cosmo, On The Beach strengthened its GraphQL foundation and created a system that is scalable and easier to maintain.

• A platform built for reliability

Cosmo replaced the stitching-based setup with automated composition, schema validation, and clear observability, giving the team more confidence in how changes move through the graph.

• Independent teams and faster releases

Domain teams now manage their own subgraphs, reducing coordination overhead and helping features move from idea to production more quickly.

• Better performance where it matters

Self-hosted router tuning and optimized query execution reduced latency during high-traffic periods and improved the overall booking experience.

• Stronger real-time experiences

Event Driven Federated Subscriptions made time-sensitive flows more dependable, including booking confirmations and dynamic pricing.

• Deep visibility and safer debugging

Advanced Request Tracing gives engineers a clear view of how queries execute, making it easier to diagnose issues and improve performance.

• An architecture aligned with how teams work

Product requirements now map more naturally to domain-driven schemas, and Cosmo helps keep schema changes safe, predictable, and collaborative.

The Conclusion

From Custom Code to a Future-Ready Federation Platform

On The Beach modernized its GraphQL architecture with a platform that provides clearer visibility, safer change management, and room to grow. Cosmo supported the way their teams already worked and helped reduce the operational overhead of maintaining a custom federation approach.

By adopting WunderGraph Cosmo, On The Beach:

• More predictable schema changes and collaboration across teams

• Improved performance and reliability during high-traffic periods

• Clearer insight into query behavior for faster debugging and refinement

Frequently Asked Question

Why did On The Beach move away from their custom Federation setup?

Their schema stitching and Apollo Rover–based setup became hard to maintain as the graph grew. It introduced operational overhead, bottlenecks, and slow rollouts, prompting the shift to WunderGraph Cosmo.

How did Cosmo improve performance and developer velocity?

Cosmo automated schema composition and validation, reducing manual overhead. Tools like the Schema Registry and Cosmo Studio helped teams own their subgraphs independently, speeding up development and reducing conflicts.

What is Event-Driven Federated Subscriptions (EDFS), and how does On The Beach use it?

EDFS lets the Cosmo router push real-time GraphQL subscription updates efficiently using a publish-subscribe model. On The Beach uses it for time-sensitive data like booking confirmations and pricing updates.

What benefits did On The Beach see from self-hosting the Cosmo router?

Self-hosting gave them more control over networking, performance tuning, and cost. They reported faster response times and better resource efficiency compared to managed federation routers.

How does Advanced Request Tracing help On The Beach?

Cosmo’s Advanced Request Tracing visualizes query execution paths and performance metrics. It helped the team optimize slow queries, debug production issues faster, and improve conversion by reducing latency.

What role did open source play in their decision?

Cosmo’s open-source model allowed On The Beach to audit the codebase, contribute features, and deeply understand how federation worked. This transparency gave them confidence and flexibility in adoption.