We do not collect any personally identifying information from users of is.gd. We store only the information necessary to provide our URL shortening service (such as original long URLs), information necessary to identify and track abuse of our service (such as IP addresses) and aggregate information to compile statistics on how individual links are used (such as browser and country of residence).
We do not share information with 3rd parties except where required to identify or track abuse or prevent future abuse (e.g. we may check submitted URLs against 3rd party blacklists and may share information on malicious URLs or abusive users with 3rd parties). The sole exception to this is when you create a QR code - we pass the relevant shortened URL (but no other data) to Google since we use their Charts API to generate these.
URLs shortened by is.gd are not private and should not be treated as such. Third parties could easily guess the short URL that you are using, so you should not use is.gd to link to sensitive or secure data.
Anonymous statistics on shortened URLs you create (such as number of visits to them, creation date etc.) are not treated as private and will be made available to anyone through the site.