Huge collection of websites to download any book

 

1. Guide to Copy Kindle Content to PDF using Calibre

2. Calibre DRM Removal Plugins 2019 — Remove eBook DRM with Calibre - DeDRM removal guide for Calibre.

3. The idiot proof guide to downloading ebooks off IRC - Posted by /u/Servaplur.

4. BookStack - BookStack is a simple, self-hosted, easy-to-use platform for organizing and storing information.

5. Ubooquity - Ubooquity is a free home server for your comics and ebooks library.

6. COPS - Calibre OPDS (and HTML) - PHP Server : web-based light alternative to Calibre content server / Calibre2OPDS to serve ebooks (epub, mobi, pdf, etc.).

7. b-ok - Free ebook library.

8. Apprentice Alf's Blog - Everything you ever wanted to know about DRM and ebooks but were afraid to ask.

9. Calibre - Management tool for ebook.

10. Calibre-Web - Web app for browsing, reading and downloading eBooks stored in a Calibre database.

11. Custom Search Engine - A Google custom search engine specifically for ebooks.

12. Exploring over 1,800 Calibre ebook servers - Blog post detailing how to use Shodan to find Calibre ebook servers.

13. DeDRM_tools - DeDRM tools for ebooks.

14. ReadAnyBook - Free online reading.

15. PDF Giant - Various categories of downloadable PDFs.

16. MagazineLib - Free PDF and interactive e-magazines.

17. Ebook 3000 - Various magazines.

18. FlipHTML5 - International magazines.

19. MagazineLib - Free PDF and interactive e-magazines.

20. magazinesdownload.org - Magazines hosted on free, fast, file-hosting sites.

21. PDF Giant - Various categories of downloadable PDFs.

22. ABook - One of the oldest book search indexers.

23. BinSearch - Binary Usenet search engine which can be used for eBooks and other stuff.

24. EBook Bike - Another search indexer which claims to be the "largest" on the Internet.

25. EBookEE - Tech, Database, Java and many many other categories.

26. FreeBookSpot - Similar to eBookEE.

27. GingaDaddy - A usenet newsgroup for eBooks. (needs login)

28. oznzb - Yet another ebook search engine.

29. PDFDrive - PDF Drive is your search engine for PDF files.

30. Via Google Search - Preset of indexed websites to search for comics.

31. r/DHExchange - PDF/eBooks trading.

32. Amazon Free Kindle Books - Top free books for download.

33. Apprentice Alf's Blog - Everything you ever wanted to know about DRM and ebooks, but were afraid to ask.

34. Authorama - This public domain book site has a wide variety of ebooks for free, by Lewis Carroll, Emerson, Kafka, and more.

35. AvaxHome - Movies, eBooks & more.

1. Mirror

36. Baen - You can download ebooks for HTML, RTF, Microsoft Reader and for Palm, Psion, and Window CE.

37. Bartleby - While Bartleby charges for some titles, it has a free ebook store here.

38. Bibliomania - You will find over 2,000 classic texts from bibliomania, plus study guides, reference material and more.

39. BitSpyder - E-Learning, tutorials & trainings.

40. BookBoon - the World’s largest publisher of online educational literature.

41. BookSC - (blocked in some countries) - Z-Library is one of the largest online libraries in the world that contains over 4,800,000 books and 75,300,000 articles.

42. BookStack - BookStack is a simple, self-hosted, easy-to-use platform for organising and storing information.

43. BookYards - This online "library to the world" has over 17,000 ebooks, plus links to other digital libraries.

44. Boundless - Affordable online textbooks & study materials.

45. Calibre Web - Web app for browsing, reading and downloading eBooks stored in a Calibre database.

46. COPS - Calibre OPDS (and HTML) - PHP Server: Web-based light alternative to Calibre content server / Calibre2OPDS to serve ebooks (epub, mobi, pdf, etc.).

47. DailyLit - Get free downloads sent to your email by RSS feed.

48. DeDRM_tools - A GitHub repository of all the scripts and other tools for removing DRM from ebooks.

49. ebookee.org - PDF & eBooks trading, various categories.

50. eBookLobby - You'll find lots of self-help, hobby and reference books here, plus children's fiction and more.

51. eLearning - Cisco, Mango, HSTalks and other eBook courses for free.

52. FeedBooks - Provides millions of books.

53. FicSave - An Open-Source Online Fanfiction Downloader.

54. Free eBooks - Besides browsing topics such as biography, fan fiction, games, history, or tutorials, you can submit your own ebook, too.

55. freebookspot.es - Various eBook's for free.

56. FreeComputerBooks - eBook categories such as Computer, Lecture Notes, Mathematics, Tutorials, Programming, and Technical books.

57. FreeTechBooks - Download free computer science, engineering and programming books, textbooks and lecture notes.

58. GetFreeEBooks - This website has free ebooks in categories from writing to the environment to fiction to business, plus features and reviews.

59. Globusz - There are no limits on the number of free books you can download on this online publishing site.

60. Guide to Copy Kindle Content to PDF via Calibre

61. Gutenberg - Project Gutenberg was the first to supply free ebooks, and today they have over 30,000 free titles in stock.

62. How can I remove DRM from my ebooks? - DeDRM tools provides a big FAQ and scripts, tools to remove DRM on eBooks.

63. iBiblio - Find archives, ebooks, tutorials, language books, and more from iBiblio.

64. Internet Archive - Over 15 mio free books & texts.

65. Issuu - Allows users to upload and distribute their publications worldwide.

66. KnowFree - Access free research, white papers, reports, case studies, magazines, and eBooks.

67. LeanPub - eBooks on programming languages such as JavaScript, C#, PHP or Ruby and guidebooks.

68. LibGen - The website has now an app that lets you search their database and download the books via their desktop app.

1. Mirror 1

2. Mirror 2

3. mirror 3

69. LibriVox - Yet another platform that offers a free download of audiobooks all over the world.

70. ManyBooks - You can conduct an advanced search, type in a title or author, browse categories or select books by language, from Finnish to Bulgarian to Catalan to Swedish.

71. Myanonamouse - Over 2 millions torrents.

72. NZBIndex - Example search for "Lynda .com". - you get the idea.

73. OnlineProgrammingBooks - Offers mobile app development, programming, computer science, web design, software engineering, information technology, networking, and databases.

74. Open Culture - Offers over 800 free eBooks to your Kindle, iPad/iPhone, computer, smartphone and eReader.

75. Open Library - Gooel's free eBook storage.

76. Planet PDF - Planet PDF has made available classic titles like Anna Karenina and Frankenstein for free.

77. ReadAnyBook - Free online eBook reading.

78. Read Print Library - Provides free novels and poems.

79. Starry.com - These novels and anthologies were last updated in 2006, but you'll still find an interesting selection of online and virtual novels.

80. TehParadox - Apps, eBooks, Games & more.

81. TheGeeks - Ebook tutorials mostly Udemy, but not limited to it.

82. Twirpx - (RU) - Fiction/Non-fiction, books in multiple languages.

83. BookTracker - (RU) - Book collections, discussions and torrents + IRC.

84. Z-Lib.org - Programming and educational eBooks.

85. dlfeb - A website that downloads eBooks from AvaxHome.

86. GoBooDo - A open-source google books downloader with proxy support.

You can also use a custom search engine or check our huge search engine list 
You can check this list if you are looking for Academics books (articles, academic papers ...)
I don't own this list, it belongs to Lucetia