How to be a modern scientist

Read-Eval-Print-λove – Forth Thinking

Ebook on configuring Babel 6 (free online)

Free python programming book - intermediate python

Practical Cryptography With Go

Intermediate Python is totally free on leanpub. Feedback is welcome

Exploring ES6

Understanding ECMAScript 6

JavaScript Allongé, The "Six” Edition, free to read online

Read CoffeeScript Ristretto

The Leprechauns of Software Engineering

New book: Game programming in Haskell

PureScript by Example - free e-book on FP for the web

Show HN: A book about the Meteor.js framework (that's available online for free)