Computer Science Unplugged — Collection of free learning activities that teach computer science through engaging games and puzzles that use cards, string, crayons and lots of running around.
Comcast — Simulating troublesome network connections so you can build better systems.
Hamms — Elicit failures in your HTTP Client — connection failures, malformed response data, slow servers, fat headers, etc.
Loband — Website that reduces webpages to the bare bones.
Offline First Resources — Everything you need to know to create offline-first apps.
Save From — Save videos from the Internet.
Kiwix Reader — Offline reader for web content. It's software intended to make Wikipedia (and other packages) available without using the internet, but it is potentially suitable for all HTML content. Kiwix supports the ZIM format, a highly compressed open format with additional meta-data.
StarWalk — Interactive astronomy guide that shows celestial objects in the exact positions on the sky above you, providing detailed information about them. For iOS and Android.
Learning Equality — Education non-profit committed to enabling universal access to high quality open educational resources, and creating tools that empower communities to author and share their own content.
Survivor Library — Public domain materials that are geared towards survival skills.
HERE WeGo Map — Offline map with Android and iOS apps.
Red Cross First Aid — Useful for emergencies, but also once you get to site this app may be a helpful educational tool to share or use for a health club. For iOS and Android.
Resilio — File synchronization between individuals and devices locally — without using the cloud.
SHAREit — Transfer files on local WiFi connections.
LibraryBox — Portable local server that offers up documents.
RACHEL (Remote Area Community Hotspot for Education & Learning) — Collection of tools and offline digital content curated for the Global South educational environment — versions use a Raspberry Pi computer or USB drive.
Bloxp — Export any blog and turn it into a downloadable e-book. Save your favorite blog as a unique, readable file.
Wikipedia Offline — Server-side tool providing web pages to cheap clients.
Calibre — E-book application suite that allows users to manage e-book collections as well as to create, edit, and read e-books.
EtherPad — Customizable online editor providing collaborative editing in really real-time.
HTTrack Website Copier — Save websites for offline viewing.
SiteSucker (MacOS) — Download websites from the Internet.
Field Papers — Print an atlas, record what you see in the world through crowdsourcing the maps, and upload the data to OpenStreetMap.
Digital Democracy — Open source, offline map editor.