Recommended translation: "Apology" in Four Texts on Socrates,  trans. Thomas G. West and Grace Starry West (Cornell University Press: 1984, rev. 1998).

Excerpt from Plato’s Apology:

“How you, men of Athens, have been affected by my accusers, I do not know; but I, for my part, almost forgot my own identity, so persuasively did they talk; and yet there is hardly a word of truth in what they have said. But I was most amazed by one of the many lies that they told—when they said that you must be on your guard not to be deceived by me, because I was a clever speaker. For I thought it the most shameless part of their conduct that they are not ashamed because they will immediately be convicted by me of falsehood by the evidence of fact, when I show myself to be not in the least a clever speaker, unless indeed they call him a clever speaker who speaks the truth; for if this is what they mean, I would agree that I am an orator—not after their fashion. Now they, as I say, have said little or nothing true; but you shall hear from me nothing but the truth. Not, however, men of Athens, speeches finely tricked out with words and phrases, as theirs are, nor carefully arranged, but you will hear things said at random with the words that happen to occur to me. For I trust that what I say is just; and let none of you expect anything else. For surely it would not be fitting for one of my age to come before you like a youngster making up speeches. And, men of Athens, I urgently beg and beseech you if you hear me making my defence with the same words with which I have been accustomed to speak both in the market place at the bankers tables, where many of you have heard me, and elsewhere,  not to be surprised or to make a disturbance on this account. For the fact is that this is the first time I have come before the court, although I am seventy years old; I am therefore an utter foreigner to the manner of speech here.”

Online:
Amazon (Recommended Translation)
Project Perseus (English, trans. Harold North Fowler, Free Access)
Project Perseus (Greek, ed. John Burnet, Free Access)
Project Gutenberg (English, trans. Benjamin Jowett, Free Access)