一个QR解码器的调试输出比zxing多**http://qrlogo.kaarposoft.dk/qrdecode.html**
根据它的作者，使用的软件是纯JavaScript，所以它运行在你自己的浏览器。
QR码解码示例（PNG由http://www.qrcode-monkey.de/编码），启用调试输出：

left=2 right=22 top=2 bottom=22
size=21
matchVersion version=1 finder0=64 finder1=64 finder2=64
matchVersion version=1 timing0=1 timing1=1 alignment=1
matchVersion version=1 format_NW =9 0 format_NESW =9 1 format = 9 ecl = 1 mask = 1
matchVersion version=1 grades(F(V)TAF): 4444->4
findModuleSize version=1 grade=4 error_correction_level=1 mask=1
getCodewords mask=1 length=26
getCodewords = 64,55,70,86,194,0,216,32,80,246,228,98,160,0,236,17,236,17,236,237,167,185,237,199,28,244
setBlocks n_blocks_first=1 n_blocks_second=0 n_blocks=1 n_block_words_first=19 n_block_words_second=0 n_block_ec_words=7 total=26
setBlocks block 0 (26): 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25
RS calculateSyndroms: No errors
correctErrors in = 64,55,70,86,194,0,216,32,80,246,228,98,160,0,236,17,236,17,236,237,167,185,237,199,28,244
correctErrors out = 64,55,70,86,194,0,216,32,80,246,228,98,160,0,236,17,236,17,236
error_grade=4
extractData bytes in (19) = 64,55,70,86,194,0,216,32,80,246,228,98,160,0,236,17,236,17,236
extractData mode = 4
extract charcount = 3
extractData mode = 2
extractAlphanum charcount = 1
extractData mode = 1
extractNumeric charcount = 10
extractData mode = 0
extractData data(14) = 116,101,108,58,49,50,51,52,53,54,55,56,57,48

字符串
注：嵌入的数据为tel:1234567890

我会使用ZXing -http://zxing.org/w/decode.jspx这样的服务
你可以给它一个QR码-通过上传或指向一个URL。
它将给予一些诊断信息，包括已编码的原始字节

Raw bytes   

44 76 d6 16 96 c7 46 f3   a7 26 56 36 97 06 96 56
e7 44 06 57 86 16 d7 06   c6 52 e6 36 f6 d3 f6 36
33 d6 f7 46 86 57 24 06   57 86 16 d7 06 c6 52 e6
36 f6 d2 67 37 56 26 a6   56 37 43 d6 86 56 c6 c6
f2 66 26 f6 47 93 d7 96   f0 ec 11 ec

字符串
如果你不想信任一个随机的网站，它是Open Source，所以你可以在本地运行它。