- The xTalk interpreter archive - Lots of HyperTalk-like programming languages, with source code
- OpenXION - A cross-platform HyperTalk-like programming language written in Java, with source code.
- stackimport - A command-line tool that exports HyperCard stacks into image files and XML suitable for import into other applications.
- CinsImp - A lightweight, fast, but fairly complete open source HyperCard clone. Source code is available.
- Pantechnicon - Lots of HyperCard stacks. These are the files that used to be hosted at the HyperCard Pantechnicon.
- hypercard.de - German web site with a large archive of stacks
- The xTalk Interviews - Short FAQ-style interviews with various people from the history of HyperCard and its clones.
- HyperCard File Format - A description of the general structure of a HyperCard stack on disk.
- AddColor Resource Format - A description of the general structure of the resources used by HyperCard 2.3 and later to store color information.
- ColdCoffee HyperTalk to Java converter - A bunch of Java source code files that read a subset of HyperTalk and create Java source code from that.
- XFromApp XCMD engine - Old C/C++ source code for running HyperCard plugins (XCMDs and XFCNs). Mostly of historical interest.
- CompileIt! Manual - This is a PDF of the manual to CompileIt!, a HyperCard stack that allows you to write HyperCard command plug-ins that access the Mac's system API and let you do everything any Mac programmer could do.
- HyperTalk Reference - This is a PDF containing screen shots of most of the pages of the HyperTalk Reference stack that came with HyperCard 2.4.
Commercial HyperCard clones
- SuperCard - The first HyperCard clone. For Mac OS X.
- LiveCode - Originally known as MetaCard, this cross-platform IDE runs on Windows, Mac OS X, Linux, Android, iOS and as a browser plugin.
- BayCard - A modern HyperCard-like system for the Mac with Button Tasks/ClickScript-style programming.
- Stacksmith - A HyperCard clone-in-development of which you can already try occasional builds.