I am trying to validate URLs and return false if such URLs happen to return gifs, like these:

• https://lh3.googleusercontent.com/nxOF05Y28F2WSBPupmOBgTuSxG-GY1BbhZJyOrjVrjKdAax0VTb4_q4_yDnNsFMTdXPZYpmr19nttJ8c1Pzzd835vOEODQGUvcPG
• https://lh3.googleusercontent.com/s4a9blztSlDXhjApbdob6CfQ6OUeIiRxb00w9-4Z2Q-6PIp9FGePtI8NBfUfgSgAki3EI2too6zdRyV9qwxdnUWaYLWGgkBa0MN_
• https://lh3.googleusercontent.com/TJIJhjYUMN2iHsS7Su_WnnfqfbQmJI8y8-zU32-GzYfbDDwofXLMRKk_Q2FTzT096dzDIyptA7-khH2tbCWwbvuWf6V4ITCf3ZncuA
• https://lh3.googleusercontent.com/4rIhhfLWqB3qUi-BMkXlyMnylwztk-HfOUQhtsmPBtfJKLh2FPNPMgL3YL6Jg0JMopsMcjaevYjXYw8lR9vFRfrZ2rsV7JXPo6mRVws

However, I cannot use regex as no URL returns something that ends with ".gif".

I have no idea how to verify the format of a file that is returned from a URL, if the said file does not have an extension at the end... may anyone point me in the right direction?