Best of GraphQL — October 2025

1. 1
   Article

   Netflix TechBlog·25w

   Behind the Streams: Real-Time Recommendations for Live Events Part 3

   Netflix engineered a real-time recommendation system to handle live event streaming at massive scale, serving over 100 million concurrent devices. The solution uses a two-phase approach: prefetching recommendations and metadata during natural browsing patterns before events, then broadcasting low-cardinality state updates via WebSocket when events start. This architecture solves the thundering herd problem by distributing load over time and minimizing real-time compute requirements. The system leverages GraphQL schemas, Apache Kafka, and a two-tier pub/sub architecture to deliver updates in under a minute during peak load, while adaptive traffic prioritization and cache jitter prevent unexpected traffic spikes.

   46
2. 2
   Article

   monday Engineering·26w

   Unmasking a hidden singleton

   A load test on monday.com's AI Reports feature revealed a critical race condition caused by a hidden singleton pattern. When multiple users simultaneously generated reports, a WorkdocsAPIService registered as a singleton shared mutable state across concurrent requests, causing workdoc IDs to override each other and trigger 400 errors. The bug remained undetected in production due to low adoption rates and high pod count, which minimized collision probability. The investigation traced through multiple hypotheses before discovering the singleton registration issue, highlighting the importance of load testing, end-to-end concurrent testing, and preferring stateless class designs in asynchronous environments.

   40
3. 3
   Article

   marmelab·28w

   Do you need a Backend For Frontend?

   The Backend-for-Frontend (BFF) pattern addresses common issues in multi-client applications where frontend teams struggle with API complexity and performance problems. A BFF acts as a dedicated translation layer between frontends and backend services, aggregating data and handling client-specific logic. While it can dramatically improve development velocity and mobile performance, it's not suitable for simple applications or small teams due to increased operational complexity.

   33
4. 4
   Article

   marmelab·24w

   From GraphQL to Zod: Simplifying Arte's API Architecture

   Marmelab helped Arte migrate from a complex GraphQL-based backend-for-frontend to a simpler REST API architecture using Zod for runtime type validation. The original GraphQL layer, implemented in 2017 to aggregate data across multiple platforms, had evolved into a REST API that internally used GraphQL.js, creating maintenance overhead and onboarding friction. By prototyping with the most complex endpoint first, the team discovered Zod could provide the same runtime type safety as GraphQL schemas while reducing architectural complexity. Key challenges included handling runtime validation, JSON serialization gotchas with undefined values, and filtering extra properties. Advanced patterns like using merge() instead of intersection() for discriminated unions proved essential. The migration reduced cognitive load while maintaining type safety, demonstrating that architectural decisions should evolve with project needs.

   27

   4