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Published directory entries matching your search.
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.
Spitfire Panorama is an interactive digital panorama of the cockpit of a 1944 Supermarine Spitfire Mark IX HF9 high-level fighter. It displays and explains all cockpit details of the aircraft. Access to the content requires HTML5/CSS3, WebGL, or Adobe Flash Player Version 9 or higher.
Splung.com is an online physics course aimed at students studying general physics at high-school, physics A-level or the first year of university. It offers sections on mechanics, electricity and magnetism, optics, heat and thermodynamics, nuclear physics and cosmology, along with Flash simulations and a forum moderated by a qualified physicist.
Springboard is an education technology company that offers online career tracks in data science, machine learning, artificial intelligence, cybersecurity, software engineering, and UX design. Its blog provides articles on certifications, skill building, and career planning. The platform also partners with employers to hire emerging talent and offers team upskilling solutions.
SQL Easy is a free interactive SQL tutorial offering 31 exercises that run against a real SQLite database in the browser. It provides hints when users are stuck and immediate feedback when a query is correct, and requires no signup. It is built by the team behind Beekeeper Studio.
Stack Exchange operates a network of over 180 community-powered question-and-answer websites covering a wide range of specialized topics. Users can ask and answer questions on niche subjects across the network's sites, which include communities for mathematics, physics, law, programming, and other fields.
Stanford CS336: Language Modeling from Scratch is the official course website for a Stanford class offered in Spring 2026. The course walks students through the process of developing a language model, including data collection and cleaning for pre-training, transformer model construction, model training, and evaluation before deployment. The site provides logistics, schedule, assignments, and course materials.
An interactive book for learning SQL that runs queries against a real-world dataset. It states it is free of charge, free of ads and requires no registration or downloads. Chapters are designed to take about 30 minutes each.
Stat Trek provides free online tutorials and calculators covering statistics and probability. Tutorial topics include AP Statistics, probability, linear regression, ANOVA, survey sampling, and matrix algebra, explained in plain English. The site also offers practice exams and a random number generator and sample size calculator for statistical work.
Staying is a code visualization platform for Python, JavaScript and C++. It animates execution flow, traces variables and monitors memory allocation, and offers code optimization suggestions. The documentation collects language support, data-structure examples and runnable code.
Stellarium is a free open source planetarium for computers. It shows a realistic sky in 3D, as seen with the naked eye, binoculars or a telescope, and offers time control, telescope control and a plugin system. The site describes it as easy to use and provides a features list and system requirements.
Stellarium is a GitHub repository or organization with source code, releases, documentation, or project resources.
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Stevens Institute of Technology is a private research university based in Hoboken, New Jersey, with a campus situated across the river from New York City. It provides undergraduate, graduate and corporate professional education programs with a focus on STEM and technology fields, and its curriculum incorporates hands-on research and co-op experiences for students prior to graduation. The university also hosts campus tours, information sessions and various events for prospective students.
StickPNG is a community site for sharing transparent PNG images. It offers curated galleries of free transparent PNGs for download and use in personal non-commercial or educational projects. Submissions must be PNG files of at least 400x400 pixels on a transparent background, and only family-friendly mainstream content is accepted.
Stitz Zeager Open Source Mathematics provides free and open precalculus materials, including College Algebra, College Trigonometry and Precalculus textbooks by Carl Stitz and Jeff Zeager. A Precalculus 4i edition is available free on the interactive Ximera platform. Printed desk copies are offered to Verified Teachers through openintro.org.
ACS Stop the Bleed offers training courses on controlling life-threatening bleeding. The course covers recognizing bleeding and three techniques: direct pressure, wound packing and tourniquet application. Online and virtual options are available, and instructors teach in person with training materials.
Storied Colors is a catalogue of historical named colors with documented sources, including provenance and chemistry. Entries are published weekly, and the site states that AI assists drafting while entries are checked before publication. It is maintained by one person.
A collection of guides on building and customizing startpages. Topics include reverse image searching, setting the new tab page in Chrome and Firefox, creating search bars with DuckDuckGo, and building terminal-like and basic startpages. The guides are not categorized, and the author states none are made for a specifically technical audience.
