SpellsList5e has a lot of spells from different sources which is very helpful. It allows to filter the spells by level, class, casting type, source, and other specifications. It also allows to search in the description of a spell, a feature I find highly useful and appreciate. SpellsList5e is very versatile which is why I use it weekly in my sessions or when I‘m preparing a character. It also has the option to enter the spell save dc and the spell casting modifier.
There are two features I’d love to see in a future update: Firstly, instead of searching spells that are on a certain list, it would sometimes be more useful to get the inverted result, i.e. all spells that are not on a certain list. For example, I‘d like a list of all third level spells not on the Bard‘s spell list (for the Magic Secrets feature).
Secondly, it would be useful to filter by damage type.