Directory
Published directory entries matching your search.
SmartCockpit is a free online aviation library offering aircraft-type specific quizzes and information on flight operations and safety. Since 2000 it has aimed to serve professional pilots worldwide, covering topics such as human factors and type rating preparation.
Snowday is an education platform that aggregates learning and extracurricular opportunities for U.S. high school students. It hosts a searchable database of over 2,100 programs, including summer, school-year, and competition options, with AI-powered filtering by location, date, and cost, plus curated expert lists and user-submitted reviews.
Solar System Scope is an online 3D simulation of the Solar System and night sky in real time, showing the Sun, planets, dwarf planets, comets, stars and constellations. It also offers a free model of the Solar System and night sky with accurate positions of objects. A desktop version and an Android app are available.
SolarHam is a space weather and aurora website founded in 2006. It provides real time data and new updates, including solar indices, imagery, flare probabilities and geomagnetic forecasts. Its help center explains space weather terms such as coronal holes, coronal mass ejections and geomagnetic storms, and notes that the section is being built.
A website providing solutions to the exercises from Hadley Wickham's Advanced R, 2nd edition. It is also the companion site for a print book listed for release in Chapman & Hall's R Series. The work as a whole is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Online Rubik's Cube timer for speedcubing that records solve times with automatic averages. The timer starts and stops by touch or the Spacebar, and an inspection time option is available.
Songsterr is a guitar tab site offering over 1 million guitar, bass, and drum tabs with free play-along original audio. It provides an AI tool to create tabs from YouTube links, and users contribute tabs through the website editor. The web app is online-only, while the mobile apps support offline mode.
SooSL is software for making and publishing a sign language dictionary. It works with any sign language and allows videos for signs, example sentences and comments, lookup by handshape, location, motion or gloss, and glosses in written languages. Version 0.9.6 is released for Windows, macOS and Linux.
Sounter is a website and mobile app for learning languages through songs, using each song as a course. Lessons cover pronunciation and vocabulary from lyrics. Languages offered include French, Spanish, English, Turkish, Polish and Portuguese. A premium option removes ads and allows offline learning. A version for teachers is also described.
Game Pauser by Jase is a tool for pausing un-pausable cutscenes and gameplay. Its source code is available for educational and private use only, not licensed for commercial purposes or distribution, and the page asks that source and builds not be separately hosted.
Space Atlas is a free, interactive 3D map of tracked satellites and rocket bodies orbiting Earth, described as covering objects from Sputnik in 1957 to today. It displays about 22,242 objects in orbit and offers real-time tracking, a timeline scrubber, and a view of satellites passing over the user's location. Orbits are approximated from the public CelesTrak catalog.
Space Time is a browser-based 3D universe explorer built from astronomical catalogs, telescope surveys and computed motion. It covers the solar system, stars, deep-sky objects and the observed cosmic web in one continuous view, with no account required. It is free and requires no download.
SpaceEngine is a virtual universe simulator for computers. Users can travel from star to star and galaxy to galaxy, landing on planets, moons and asteroids, and can alter the speed of time. Real celestial objects appear alongside procedurally generated regions based on scientific knowledge.
SpaceFromSpace is an archive of satellite imagery that includes declassified Cold War reconnaissance photographs and modern spaceport views. Images are stitched and georeferenced from raw USGS datasets and presented on interactive maps, with galleries covering declassified, spaceport and recently added scenes.
SpaceSim is a free 3D space simulator that runs in a browser. It offers travel across the Solar System, time changes, source-backed worlds and postcards, along with journeys such as a grand tour of the Solar System, an ISS trajectory view and a procedural stellar laboratory for known stellar objects.
Space Telescope Live is an X account that provides up-to-date information on current, past and future observations from the Hubble Space Telescope and the NASA Webb telescope. It asks what the two telescopes are looking at right now and links to spacetelescopelive.org.
SpaceWeather.com presents news and information about solar flares, geomagnetic storms, auroras, meteor showers, and near-Earth asteroids. The page displays current solar wind speed and density, X-ray solar flare levels, the daily Sun image, sunspot number, auroral oval, planetary K-index, and interplanetary magnetic field data.
A social media account for SpaceX, described in its profile as designing, manufacturing and launching rockets and spacecraft. The page lists 11.9K posts and 41.9M followers and links to the company's website.
SpanishChecker is an online editor that finds common spelling and grammar errors in Spanish. Users type or paste text into the editor, which reports possible errors and a grammar score. The site also offers vocabulary and grammar resources and references its French counterpart BonPatron and English counterpart ESLwriter.
Speechling offers a collection of free language learning tools, including listening comprehension practice, dictation practice, vocabulary flashcards, fill-in-the-blank exercises, a language quiz, and an audio dictionary. The tools are described as free forever and require no login.
SpeedCrunch is a free, open-source high-precision scientific calculator licensed under the GPL. It features a fast, keyboard-driven interface that displays results as users type, with a scrollable input history, customizable syntax highlighting, and an optional on-screen keypad. The calculator supports over 80 built-in mathematical functions, user-defined functions, variables, calculations with up to 50 digits of precision, complex numbers, numeral bases, unit conversions, and includes a library of over 150 scientific constants and common formulas. It is available for Windows, macOS, and Linux in multiple languages.
SpeedCubeDB is a free online speedcubing algorithm and reconstruction database. It covers algorithms for 2x2 through 6x6 cubes as well as Square 1, Pyraminx, Megaminx, and Skewb. The site also lists practice tools including a scramble analyzer and cross trainer, and offers login for tracking progress.
SpeedSolving is an online speedcubing community that started in 2006. It hosts a forum, wiki, weekly competitions, a timer and a media gallery. Members can ask questions, enter weekly competitions in WCA puzzle events and track their times and personal bests.
Spinning Up is OpenAI's educational resource on deep reinforcement learning. Its documentation covers installation, included algorithms, running experiments, and an introduction to RL, along with algorithm pages for methods such as DDPG and PPO. The DDPG page describes an algorithm that concurrently learns a Q-function and a policy for continuous action spaces. The PPO page describes on-policy first-order methods, including PPO-Clip.
