There are plenty of translated editions out there with annotations, like the Focus series. Even the more bog-standard ones like the Penguin Classics and Oxford World's Classics editions sometimes have good notes.

If you're after something more general, or more advanced, there are plenty of books of that kind too, like Michael Silk's Aristophanes and the definition of comedy (2000). On historical context, a good bet might be Michael Vickers' Aristophanes and Alcibiades: echoes of contemporary history in Athenian comedy (2016). And there are also more abstract books like Dimitrios Kanellakis' Aristophanes and the poetics of surprise (2020); then there's Jeffrey Henderson's classic study of sexual and scatological humour, The maculate muse (1975).

If you want more detailed notes on specific jokes, you may need to resort to a commentary. These are typically written for students and scholars who know ancient Greek, like the Oxford series, but there are a few out there that are pitched at people with limited or no Greek: I'm thinking of things like the Aris & Phillips series published by Liverpool University Press (scroll down to Aristophanes), which includes a translation alongside the Greek text and with notes, edited by top scholars.

Some of these books may be available in digital form, but you won't find anything online for free.