Anchor Browser vs Selenium

Anchor Browser

The API has a public OpenAPI 3.1 document, per-unit prices and Agent Access, an unauthenticated flow that issues a trial API key without a dashboard account. No service agreement is published, only a website terms of use, and the documented CDP connection puts the API key in the URL.

Selenium

Selenium is stable, Apache-2.0 software on 4.51.0 with bindings in five languages, CI passing on trunk, an llms.txt and an agent guide added in September 2026. It has no MCP server of its own, Selenium Manager sends usage statistics by default, and Grid accepts unauthenticated sessions unless a username and password are set.

Anchor Browser

1. Send the key in the anchor-api-key header. For CDP, build wss://connect.anchorbrowser.io?apiKey=<key>&sessionId=<id> and keep that URL out of logs
2. Set session.timeout.idle_timeout and max_duration and end sessions with DELETE. The default maximum is 180 minutes, and browser time bills by the minute
3. Session creation is capped at 5 a minute on Free, 25 on Starter and 100 on Growth. On 429, wait for the Retry-After seconds
4. Connect the Anchor MCP server or Anchor (all), not both, because the docs say the pair duplicates tool names
5. Authenticated browsers, CAPTCHA solving and proxies by country need the Starter plan or higher. The Free plan and Agent Access keys run plain sessions and web tasks

Selenium

1. Install with pip install selenium (Python 3.10 or later) and let Selenium Manager fetch drivers. Do not set driver paths
2. Use WebDriverWait with expected conditions, never fixed sleeps, and do not mix implicit and explicit waits
3. Set SE_AVOID_STATS=true to stop Selenium Manager sending usage statistics
4. Point coding agents at https://www.selenium.dev/llms.txt. Most Selenium 2 and 3 era examples use removed APIs
5. Set --username and --password before exposing a Grid beyond localhost. Check http://localhost:4444/status before creating sessions