The official Turkish Language Association dictionaries, free and ad-free.
Details
The Türk Dil Kurumu's portal bundles the current monolingual dictionary (12th edition, 2023) with a proverbs-and-idioms dictionary of several thousand entries, an etymological dictionary, spelling guide, science and arts terminology and a Turkish Sign Language dictionary. It is the authority Turkish speakers themselves cite for spelling and usage questions. Everything is monolingual Turkish, so you need roughly B1 to get value from it. Free, no ads, with an official mobile app.