The CMU Pronouncing Dictionary gives phonemic-level transcription for around 130,000 words of American English. However the data is in an obscure ASCII-based transcription system that you might not want to learn how to read. If not, click here to download the dictionary in IPA format. What you’ll get after you unzip it is a Unicode text file. If you have trouble displaying it, try opening the file in a web browser and setting your character encoding to UTF-8 (under the View menu). Please let me know if find any problems.