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Maximum compression for e-books without quality loss — up to 5-30% (Lossless)! Full compatible with original formats. The document is reduced by repacking the contents with a stronger compression algorithm. It uses 2 programs and selects the best result: ECT (Efficient Compression Tool), AdvanceCOMP. Compression mode: good (faster) or best (slowly). Batch processing of files (drag-n-drop). Program optimizes your file to new one with «_optimized» name ending (source file will remain intact). Output files have their timestamps/permissions set to match those of their inputs. It saves quality of all pictures inside your ebooks. ePub is a free and open e-book standard by the International Digital Publishing Forum (IDPF). FictionBook (FB3) is an open XML-based e-book format.