Browser Use Releases 'Jev Ultrafast', a High-Speed Browser Agent Based on Dynamic Indexed Action Space

Browser Use and TypeSafe have collaborated to release Jev Ultrafast, a browser agent that applies a dynamic indexed action space. Unlike traditional methods, this project operates without site-specific pre-prepared scripts or field strings, generating a new element table for every observation.

Core Working Principle

TypeSafe's Jev proposes both the operation and the target (element) simultaneously in a single network round trip. Supported operations include CLICK, TYPE_TEXT, SELECT, SCROLL_UP, SCROLL_DOWN, WAIT, DONE, and BLOCKED. Specifically, a small LLM is invoked only when text input (TYPE_TEXT) is required to generate text, thereby reducing unnecessary computational costs.

Performance and Optimization

Searching for flights from Zurich to London on Google Flights takes 7.1 seconds, including time from natural language goal input to loading wait. Repeated test results showed that the median task time decreased by 25% from 9.450 seconds to 7.092 seconds, and the number of browser protocol calls dropped significantly from 1,092 to 101.

The following techniques were applied for performance optimization:

• Limiting requests to one per decision cycle
• Using structured state instead of screenshots in the main loop
• Minimizing browser calls per snapshot to one via atomic DOM reads
• Verifying document/form/occlusion status of selection targets

Security and Limitations

Model outputs do not become direct selectors or commands; instead, page freshness and clickability are re-verified before execution. However, Shadow roots, frames, canvas, uploads, and popup tabs are currently excluded from the MVP scope and are not supported.