I try to learn Latin vocabulary with macrons.
But online dictionaries, either don't give the diacritic, or give them only for the nominative, have some errors, or give only macrons, and no apices.
For instance, vātēs, sometimes it's given "vātēs" only in singular, and "vates" in plural, sometimes there are no macrons at all, and sometimes both singular and plural have macrons.
For instance, macron only on the singular: https://www.online-latin-dictionary.com/latin-dictionary-flexion.php?lemma=VATES100
Macron only on the plural: https://fr.wiktionary.org/wiki/vates
In many books, it's not consistent. So, while I have Gaffiot and Lewis & Short as my references for definition and usage, I didn't find a good source (online), errors-free, for apices & macrons.