Most "free" sites survive on aggressive ad networks that can install trackers or malware on your device.
Check JustWatch or Reelgood . These sites allow you to type in "Interstellar" and see exactly which platform is currently hosting it for free or as part of a subscription in your specific country. interstellar2014 free
If you want the highest bitrate (essential for the Gargantua black hole visuals), renting it for a few dollars on , Google Play , or YouTube is the best move. It’s a small price to pay for a 4K HDR experience that your laptop speakers won't do justice to anyway. Why Interstellar is Worth the Effort Most "free" sites survive on aggressive ad networks