Majestic SEO crawler (MJ12bot).
Official: majestic12.co.uk/bot.php
Send the User-Agent to the API, device, OS, browser, and bot detection come back in one response. MJ12 Bot is identified by name when the string matches.
curl -s "https://api.parseapi.com/useragent" \ -H "User-Agent: Mozilla/5.0 (compatible; MJ12bot/v1.4.8; http://mj12bot.com/)" \ -H "X-Api-Key: $PARSEAPI_KEY"
Real strings from our archive that resolve to MJ12 Bot. Each opens a full breakdown.