The Latin Endings DataBase (or LEDB) by itself stores endings found in Latin from the following parts of speech or words:
Nouns
Verbs
Adjectives
Relative pronouns
The website for LEDB (which you're on right now) has a ending picker below where you can plug in the aspects of the ending you're looking for (e.g. gender, number, case, and declension) and get the resulting ending out.
The actual database itself can be found here, and is encoded in JSON within JavaScript, to allow missing/impossible endings to be indicated and have customized appearances (by default, unknown endings/endings missing in the database will mark as a "?", "any" endings will be marked as a "*", and impossible endings with a "☒".
Also note that Unicode letters or letters with lines above them like ā, ē, ī, ō, or ū are encoded with Unicode escape sequences in the database itself, as \u0101, \u0113, \u012b, \u014d, or \u016b respectively.
Ending Picker
Usage
To use the ending picker, select the part of speech you're looking for and then set the dropdowns accordingly to look for the ending.
For example, if you have "frater, fratis, m." you'd look for 3rd declension masculine nouns.
ENDING: -a
Ending Searcher
Usage
To use the Ending Searcher, first select a part of speech (e.g. relative pronoun) in the Ending Picker. Then, you can search through the endings by typing the ending out (e.g. "quod"). It will then show all the possible results in the dropdown below the bar (e.g. nom, sg.n and nom, pl.n). You can then click the dropdown option(s) to select the ending and autofill the Ending Picker.