myip.ninja is a very simple piece of code that gives you back your IP in plaintext for usage wherever you like like in bash scripts. myip.ninja can also give you specific IPs like v4.myip.ninja and v6.myip.ninja. myip.ninja works over both http and https.
#curl myip.ninja
> 8.8.8.8
#curl v6.myip.ninja
> aced:a11:7e57
#curl myip.ninja/?format=json
> {"ip":"8.8.8.8"}
#curl myip.ninja/?format=jsonp&callback=cb
> cb({"ip":"188.189.89.234"});
#curl myip.ninja/?format=xml
> <?xml version="1.0" encoding="UTF-8"?>
> <IP>188.189.89.234</IP>
myip.ninja is used to detect your External IP, this can be handy when you're behind a NAT or when not even sure where the script will be used.
myip.ninja is developed for internal use at SHOUTca.st where it has been in production use for years.
myip.ninja is paid for by SHOUTca.st, We don't see such extreme use that we're not able to pay for it anymore. If you plan super heavy use we suggest hosting it yourself.