8 Key Upgrades in Browser Run's Cloudflare Containers Migration

When we first launched Browser Run, we knew it had enormous potential—but like any growing platform, it faced growing pains. Shared infrastructure with Browser Isolation (BISO) limited performance, scalability, and deployment speed. This year, we took a bold step: rebuilding Browser Run on top of Cloudflare's Containers. The results are dramatic—faster response times, higher concurrency limits, and a more reliable platform for developers. Here are the eight things you need to know about this upgrade.

1. What Exactly Is Browser Run?

Browser Run gives developers programmatic control over headless browser instances on Cloudflare's global network. You can use it for end-to-end web application testing, investigating suspicious URLs safely, rendering PDF documents, capturing screenshots, or extracting content. It's become a critical tool for AI agents that need to interact with the web. The platform is designed to be the go-to solution for responsibly managing automated browsers at massive scale.

2. The Old Shared Infrastructure Bottleneck

Before Containers, Browser Run shared its infrastructure with Browser Isolation (BISO). That sounded efficient, but it created real problems. BISO's container images were much larger, slowing down startup times and making development iterations painful. More critically, BISO browsers weren't optimally distributed globally, which meant lower resiliency and higher latency for Browser Run users. The usage patterns clashed too: BISO sessions were long and steady, while Browser Run users had short, spiky bursts. This mismatch led to scaling bottlenecks and availability delays.

3. The Move to Cloudflare Containers

Cloudflare's internal team had been working on Durable Object (DO)-enabled Containers, which entered open beta last year. For Browser Run, that was the perfect moment to migrate. By building on our own platform, we could feel and fix pain points before any external customer encountered them. The migration wasn't instant—it required careful planning and a gradual rollout—but it was worth it.

4. 4x Higher Concurrency and 50% Faster Quick Actions

The most visible improvements are in performance. With the new Container-based architecture, you can now spin up 60 browsers per minute via the Workers binding and run up to 120 browsers concurrently—that's four times the previous limit. Quick Action response times have dropped by more than 50%. These aren't theoretical numbers; they're live right now. No code changes needed on your end.

5. A Carefully Phased Migration

We didn't flip a switch and hope for the best. The team inserted a Worker into incoming request paths to serve a small percentage of users from Containers while most still used BISO. This dual-running approach allowed us to compare performance, find bugs, and build confidence. We then expanded Container browsers to Quick Actions endpoints first, then to free account Workers bindings, then pay-as-you-go, and finally to all contract customers. Each step validated stability before proceeding.

6. Overcoming Scaling Challenges

Migration always has its rough edges. One challenge was ensuring the Container-powered browsers matched or exceeded the reliability of the BISO-backed ones during the transition. The team had to tune container image sizes, optimize global distribution, and adjust for the different usage patterns. By using a phased approach and measuring everything, we were able to address issues before they affected users.

7. Zero Effort Required From You

One of our core principles is that improvements should be invisible to customers. When you use Browser Run today, you're already benefiting from the Container upgrade without changing a single line of code. Your existing Workers bindings continue to work, and your browser instances are faster and more available. This is a major win for developer experience—no migration steps, no downtime, just better performance.

8. What's Next for Browser Run

The Container migration opens the door for faster feature development. With a dedicated infrastructure, we can ship fixes and new capabilities more rapidly than before. Expect even higher concurrency limits, smarter auto-scaling, and deeper integration with other Cloudflare services. Browser Run is poised to become an even more essential tool for developers building modern web applications and AI-powered agents.

This migration wasn't just about moving from one infrastructure to another—it was about unblocking the future. By rebuilding on Cloudflare Containers, we've made Browser Run faster, more scalable, and more reliable. And we're just getting started.