【Straightforward】 , 【forthright】 , 【aboveboard】 when applied to persons, their actions, or their methods mean honest and open.
Something 【straightforward】 is consistently direct and free from deviations or evasiveness.
Something 【forthright】 has directness like that of a thrust, or goes straight to the point without swerving or hesitating.
Something 【aboveboard】 is free from all traces of deception or duplicity. 【Aboveboard】 is chiefly used predicatively and applies more often to actions or methods than to persons.
【Straightforward】 , 【forthright】 , and 【aboveboard】 are also used adverbially with the same implications and connotations as their adjectival forms.