Actually, PDF is primarily a text format, it's just usually compressed, and often contains embedded binary content like fonts and images. You can see the text

Actually, PDF is primarily a text format, it's just usually compressed, and often contains embedded binary content like fonts and images. You can see the text code by doing something like this: pdftk input.pdf output input_uncompressed.pdf uncompress You can also edit it in that state, in an editor that preserves binary content, but there's a hard-coded offset table at the end, so if you change the length of something, that needs updating (very fiddly to attempt by hand, but automatable, and some pdf tools automatically fix broken offset tables).