Scaling Browser Run: Faster Performance and Higher Limits with Cloudflare Containers
Browser Run, Cloudflare's headless browser automation service, has undergone a major overhaul. By migrating to Cloudflare Containers, it now delivers faster performance, higher concurrency limits, and improved reliability — all without requiring any changes from users. This Q&A explores what changed, why, and what it means for developers.
What is Browser Run, and what can developers do with it?
Browser Run is a platform that lets developers programmatically control and interact with headless browser instances running on Cloudflare's global network. This capability is valuable for end-to-end testing of web applications, securely investigating suspicious URLs, rendering PDF documents, capturing screenshots, and extracting content. More recently, it has become a critical enabler for AI agents that need to interact with the web. Browser Run aims to be the go-to platform for responsibly using automated browsers at massive scale, balancing powerful functionality with security and reliability.
Why did Browser Run move away from shared infrastructure with Browser Isolation?
Previously, Browser Run shared infrastructure with Browser Isolation (BISO). While technically similar, BISO's larger container images caused slower startup times and hindered development. More critically, BISO browsers lacked optimal global distribution, leading to compromised resiliency and higher latency. The usage patterns also clashed: BISO users typically had long, steady sessions, while Browser Run experienced short, spiky traffic. This created scaling bottlenecks and availability delays. The move to dedicated Cloudflare Containers resolved these issues, allowing each platform to optimize independently.
How did the migration to Cloudflare Containers unfold?
The migration was gradual and carefully staged. Engineers inserted a Worker in the incoming request paths to serve some Container-powered browsers alongside those from BISO. This dual support allowed performance comparisons and helped isolate bugs. Confidence grew, and the team first used Container browsers for all Quick Actions endpoints, then for connections via the Workers browser binding on free accounts, followed by pay-as-you-go accounts. Finally, the change rolled out to all contract customers. The entire transition required no action or existing Worker redeployments from customers — improvements went live automatically.
What specific performance and scalability improvements were achieved?
The switch to Cloudflare Containers brought dramatic gains. Users can now spin up 60 browsers per minute via the Workers binding and run up to 120 concurrently — that's 4 times the previous limit. Quick Action response times dropped more than 50%, making interactions snappier. Additionally, the team can ship fixes and new features faster than before. These improvements are live immediately; no configuration changes or code updates are needed on the developer side.
How do the new usage limits compare to the previous ones?
Previously, Browser Run supported much lower concurrency. The new limits of 60 browser spins per minute and 120 concurrent browsers represent a 4x increase. This is especially beneficial for developers running large-scale end-to-end test suites or AI agents that need to interact with many web pages simultaneously. The platform also now handles short, spiky workloads much better, reducing the chance of throttling or queuing. These numbers are available to all users, regardless of account type, as part of the upgrade.
What role do Cloudflare Containers and Durable Objects play in this update?
Cloudflare Containers, enabled by Durable Objects (DO), provided the foundation for this migration. The open beta of DO-enabled Containers allowed the Browser Run team to experiment early. Containers offer faster startup times and better global distribution compared to the shared BISO infrastructure. They also allow per-browser isolation and resource allocation, which is critical for security and performance. By building on Cloudflare's own platform, the team can quickly iterate and fix any issues before they affect external customers.
Is any action required from existing users to benefit from the improvements?
No, the improvements are live and fully backward-compatible. Existing Workers using the Browser Run binding continue to work without any code changes. The migration was designed to be transparent — users automatically get the higher limits, lower latency, and greater reliability. If you haven't tried Browser Run yet, now is a great time to start, as the platform is more capable and responsive than ever.