There are a number of pages hosting The Hunchback of Notre-Dame e-text; these are the ones I found least annoying.

 

          Notre-Dame de Paris
       Isabel F. Hapgood translation

       The whole novel on one page, black text on white, no ads. Includes Author's Preface and Note Added to Definitive Edition.

 

          Notre-Dame de Paris en français

       The novel in the original French. Divided by book and chapter. Black text on white. Minimal ads. A very nice site.

 

          The Hunchback of Notre Dame -- Project Gutenberg etext
       Isabel F. Hapgood translation

       Plain text, whole novel on one page, no ads. Includes Author's Preface and Note Added to the Definitive Edition.

 

          Bartleby.com: Notre-Dame de Paris
       (translator not named)

        A very convenient page, but an inferior translation, in my opinion. Black on white text with linked footnotes. Includes index with links to chapters, biographical note, criticisms and interpretations, list of characters, the Author's Preface to the Edition of 1831, and Appendix. Some advertisements.

 

          The Literature Network: The Hunchback of Notre-Dame
       Isabel F. Hapgood translation

       Black text on white. Minimal adds. Divided by chapters. Lacks Preface and Note Added to the Definitive Edition.