it’s a series written by a dude that looks like Jonathan Frakes…
it’s about three girls that live very close to each other so they can send each other secret messages and in every book there was a new type of code that you could use to decipher the messages…
They find a talking toad in some kind of basement/secret room in the museum or something and get tasked with catching monsters… it was actually a super nice series and I had six or seven books but I can’t remember the name
Cyberrat Writes 