For base gifs:
You must be registered to see links
or google.
also, gelbooru, realbooru, sex.com too look up r rated gifs, just remember the rules when posting. Also, tenor uses slightly different urls for the same image but different qualities. https://media.tenor.com/ureIeP-iC1AAAAAM/did-you-do-it-what-did-it-cost.gif The M at the end of the link denotes shitty quality, If you care at all about that, replace that M for a C (case sensitive) like so, https://media.tenor.com/ureIeP-iC1AAAAAC/did-you-do-it-what-did-it-cost.gif
For basic editing:
You must be registered to see links
For adding heads with motion tracking:
You must be registered to see links
(this adds a watermark, you can do stuff to prepare the base beforehand with ezgif and then remove it with the same site afterwards.)
If I want to make a base gif because of source quality issues:
to grab stuff from youtube, you can select the quality.
to cut large videos (movies, shows) down to manageable clips, you can burn in subtitles into the clips.
to make higher quality base gifs than what ezgif usually provides. It's very basic and has some limitations but it can give you a nice file to then edit with ezgif and gifmemes.
there's plenty of free tools out there, this is just the one I found that was lightweight and had what i needed even though it's basic/limited.