Lexmount Cloud Browser

Use Lexmount cloud browser for large-scale automated evaluation

Lexmount provides cloud-based browser instances for running browser automation tasks. Supports session persistence, login state management, and large-scale parallel execution.

Service Endpoints

Lexmount offers two production regions. Choose the one closest to where your evaluation is running:

Environment	Console	API base URL
Production (mainland China)	browser.lexmount.cn	https://api.lexmount.cn
Production (international)	browser.lexmount.com	https://api.lexmount.com

The API base URL is optional — the SDK defaults to the mainland China endpoint. Override it via LEXMOUNT_BASE_URL in .env or lexmount_base_url in config.yaml when running from outside mainland China.

Prerequisites

1. Get API Key

   Register at the Lexmount console (browser.lexmount.cn for mainland China, browser.lexmount.com for international) and apply for an API Key.

2. Get Project ID

   Create a project in the same console to get the Project ID.

Configuration

Add credentials to .env:

LEXMOUNT_API_KEY=your_api_key
LEXMOUNT_PROJECT_ID=your_project_id

Copy the example config (cp config.example.yaml config.yaml), then configure the cloud browser for the target agent in the root config.yaml:

# config.yaml
agents:
  browser-use:
    browser:
      browser_id: lexmount
      lexmount_browser_mode: normal   # normal | light
      lexmount_api_key: $LEXMOUNT_API_KEY
      lexmount_project_id: $LEXMOUNT_PROJECT_ID

Login Contexts

For tasks requiring login, use the bubench login subcommand to create a persistent Lexmount context that stores the login state. At evaluation time the runtime auto-forks this context based on each task’s target_website — one login serves many concurrent runs.

Step 1: Save a Login

# Xiaohongshu
bubench login add xiaohongshu

# Taobao
bubench login add taobao

# Custom URL (sites not in the built-in registry)
bubench login add my_site --website https://example.com/login

The command prints an Inspect URL — open it in your local browser, complete the login, then return to the terminal and press Enter to persist cookies into the context.

Nearly 100 common sites are built in (e-commerce, social, video, office/collab, etc.). Run bubench login add help to list them all, or edit browseruse_bench/browsers/login_sites.yaml to add your own.

Step 2: Login Flow

1. Run the command

   bubench login add <site> creates the context, opens a remote session, and prints an Inspect URL

2. Log in via the browser

   Open the Inspect URL locally — the remote Chrome is already navigated to the target site. Log in normally

3. Confirm & save

   Press Enter in the terminal. The session closes cleanly and cookies persist into the base context

The mapping is recorded in browser_data/login_contexts/index.json.

Step 3: Other Commands

# List all saved login contexts
bubench login list

# Remove local mapping only (keep remote context)
bubench login remove xiaohongshu

# Also delete the remote Lexmount context
bubench login remove xiaohongshu --delete-remote

Running Tasks with Login

Any task with login_required: true whose target_website resolves to a saved site will auto-mount the matching context — no extra flags needed:

1. Ensure login exists

   Run bubench login list to confirm the target site is saved

2. Use Normal mode

   # config.yaml
   agents:
     browser-use:
       browser:
         browser_id: lexmount
         lexmount_browser_mode: normal
   
3. Run tasks

   bubench run \
     --agent browser-use \
     --benchmark LexBench-Browser \
     --split high_freq_login \
     --mode first_n --count 5
   

Advantages

No Local Browser

Runs in server environments without Chrome installed

Session Persistence

Login state persists across tasks, no repeated logins

Parallel Execution

Supports multiple browser instances running in parallel

Stable & Reliable

Cloud-isolated environment avoids local resource conflicts

Notes

• Cloud browser usage incurs costs — use responsibly
• Normal mode sessions have an expiry time — check login state regularly
• Do not expose your API Key in public environments