WordNet records no synonym and no antonym for submitter. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
someone who yields to the will of another person or force
someone who submits something (as an application for a job or a manuscript for publication etc.) for the judgment of others
“he was a prolific submitter of proposals”
Synonyms, antonyms and the broader and narrower relations for submitter come from Princeton University’s WordNet. Full sources and licences.