The phrase "with confidence" is commonly used to describe someone who is assured and self-assured in their actions or decisions. However, there are several synonyms that can be used to convey the same idea, including "assuredly," "certainly," "confidently," "fearlessly," "intrepidly," "positively," and "seamlessly." Using synonyms can add variety and nuance to writing and speaking and can help to avoid repetition. Ultimately, the choice of synonym will depend on the context and tone of the message being conveyed, as well as the intended audience.