KameSame is a fantastic free Japanese SRS tool. One key feature is that it can pull items from a list of the exact same kanji and vocabulary offered by WaniKani in the same order. The only feature that the WaniKani subscription actually unlocks is the ability to complete lessons and reviews in the SRS system. You can still search for any item in the WaniKani curriculum without paying anything. And the item pages contain ALL of the information you see in lessons. In fact, some userscripts like the absolutely legendary Keisei Semantic-Phonetic Composition actually work on item pages!
When I need to learn items that exist in WaniKani before I’ve unlocked them. I’ll find them in KameSame, and if it tells me it’s a WaniKani item (which has been the case for literally every kanji so far), I’ll open the WaniKani page and utilize the mnemonics and additional information (largely improved by some scripts) to learn the item more quickly and easily. You could do the same, but extended to every item.
The only thing you won’t have in KameSame are WaniKani’s radicals, which aren’t actually an aspect of reading/writing Japanese per say, but are learning tools used to make kanji easier to memorize, and they show up in all the kanji mnemonics on WaniKani. If you want to memorize and use these radicals as if you had the paid WaniKani experience, you could add them to a custom Anki deck as you go, or you could still do everything above and use your own mnemonics with this technique:
I use a mix of both, and the only real reason I personally use WaniKani at this point rather than KameSame only, is for the convenience of how much it streamlines Kanji study, mostly thanks to userscripts that allow me to see a bunch of information on one page that would otherwise need to be individually searched for on several different web sites.
These screenshots are all from the item pages that you can access without subscribing. (There's way more than this, I'm just showing some additional features you can get from scripts if you want.)
First, here’s how to search for items.
Keisei Semantic-Phonetic Composition
Stroke Order Diagram
WaniKani Pitch Info