*Note - This list is largely based on an open source list provided by the Free Ebook Foundation - you can checkout their version of the list here.

Ada


APL


Arduino


Assembly Language


Awk


Bash


Basic


C


Chapel


Cilk


C Sharp


C++


Clojure


COBOL


CoffeeScript


ColdFusion


Coq


D


Dart


DB2


Delphi / Pascal


DTrace


Elasticsearch


Elixir


Emacs


Embedded Systems


Erlang


F Sharp


Forth


Fortran


FreeBSD


Go


Gradle


Grails


Haskell


HTML / CSS


Haxe


IoT


Isabelle/HOL


J


Java


JavaScript


Lisp


Lua


Mathematica


MATLAB


Maven


Mercurial


Oberon


Objective-C


OCaml


Octave


OpenGL ES


OpenSCAD


Perl


PHP


Prolog


Python


Django


Flask


R


Racket


Ruby


RSpec


Sinatra


Ruby on Rails


Rust


Sage


Scala


Scheme


Scilab


Smalltalk


Subversion


Squirrel


TeX


TypeScript


Unix


Git


Hadoop


Linux


Vim


Standards


Sql


MySql


NoSql


iOS


Android


D3


Mathematics


Machine Learning


Graphics Programming


Algorithms & Datastructures


Theoretical Computer Science


Operating systems


Databases


Networking


Compiler Design


Programming Paradigms


Parallel Programming


Software Architecture


Open Source


Datamining


Cellular Automata


Web Performance


MOOC


Professional Development


Security


Computer Vision


Licensing


Partial Evaluation


Regular Expressions


Reverse Engineering


Misc


Other free books/reading material


Screencasts


Interactive games


Interactive/other learning material

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