For a recent project for my university on a similar topic we made use of the Oxford Learner's Dictionaries. Using a parser, you could easily look up a verb (or any word) by using the URL of the query function, e.g.:
The results display British English and American English transcriptions and conjugations. Words that are spelled the same but are different parts of speech are located on different pages, for example:
start (verb): https://www.oxfordlearnersdictionaries.com/definition/english/start_1
start (noun): https://www.oxfordlearnersdictionaries.com/definition/english/start_2
This means that if one needs to get information for a specific verb, they could check the type specified on the page and if it's not the one they're looking for, they could iterate the number in the URL until HTTP 404 is returned.
While not pretty, I've got some code that might help with parsing the content of the Oxford Learner's Dictionaries on the project's GitHub page.