This form allows you to select a file on your computer Chinese characters. It will return that file, with pinyin added next to the characters. You can select the level of pinyin added to the page. For example, if you select level 1 (beginning), all characters in the page will have pinyin added. If you select 2 (intermediate beginning), all characters above the 500 most frequently used characters will have pinyin added, if 3 (advanced beginning) then all above the 1,000 most frequently used characters, and so on up to level 10 which will only list characters less common that the 4,500 most commonly used characters. If you can reach this level, then my hat goes off to you. Either way, you can select the level that best suits your ability.
Some characters can have multiple pronunciations, depending on context. This tool gives all of the possibilities. However, you can visit the Annotator page for some attempts to make the conversion process more accurate by giving the correct pronunciation for each character in context.
You also have the option of how many times pinyin will be added for a character. If "Only Add for First" then pinyin will only be added for the first occurence of the character, if "Add for All" then pinyin will be added for each occurance of the character.
The GB file used is missing about 300 characters, but they are the most uncommon characters so this should not a problem unless you are a student of ancient Buddhist texts.
This tool was written by Erik Peterson as part of his set of On-line Chinese Tools.