Directory
Science and mathematics collects references, databases and study material for science and maths subjects. The listings cover chemistry, physics, biology, astronomy, earth science and maths, with a mix of reference databases, course pages, calculators, simulations and self-assessment tools. Some entries are large public databases such as compound or species catalogues, and others are small teaching sites or video series. Worth checking: the level each resource aims at, the date of its data and whether the authors are named. Accuracy matters most here, so prefer sources that explain how their numbers were produced.
Richard Nakka's Experimental Rocketry Web Site shares experiences, ideas and technical details of amateur experimental rocketry, where rockets and their motors are built from scratch. It includes the author's notes, flight logs and photographs, plus work by others. The site was originally posted in July 1997 and a 2026 downloadable version is offered for purchase.
Name-Reaction.com presents organic chemistry reactions with detailed, step-by-step mechanisms. Each step is shown without shortcuts, with colour-coded lone pairs and reaction arrows. Hovering over a reaction name gives a schematic preview of reagents, conditions and products, and references are retrieved from science journal databases in ACS style with links to article titles and DOIs.
NAR is an educational resource for documentaries, courses, books, reference material, or self-learning.
Nextstrain is an open-source project that tracks pathogen evolution in real time using pathogen genome data. It provides bioinformatic workflows, analysis tools and visualization apps, plus featured analyses of pathogens such as SARS-CoV-2, Ebola, measles and influenza. Nextclade offers in-browser phylogenetic placement, clade assignment, mutation calling and sequence quality checks.
Number Academy provides educational lessons, courses, tutorials, or study material for self-learning.
OEIS is the On-Line Encyclopedia of Integer Sequences, maintained by The OEIS Foundation Inc. The site is available in many languages. It offers lookup, an index, plots and transforms, and reports containing 400313 sequences.
OneConverter is a free online service for converting PDF files and units of measure, intended for work, study and business. It offers file conversion, unit converters and PDF tools such as merging, splitting and compressing, and works on Windows, Mac and Linux with an internet connection.
OneZoom is an interactive tree of life explorer that shows how all life on Earth is related on a single zoomable page. Each leaf represents a different species, and branches illustrate evolution from common ancestors. The site offers guided tours and is a registered non-profit in the UK with products available for free.
OpenDroneMap is drone mapping software that generates maps, point clouds, 3D models and DEMs from images taken by any camera in any orientation. Its ecosystem includes ODM, a command line toolkit for processing aerial images from drones, balloons or kites, plus NodeODM, CloudODM, PyODM, ClusterODM and other projects.
OpenFOAM is a free, open source computational fluid dynamics (CFD) software developed primarily by OpenCFD Ltd since 2004. It offers an extensive range of features for solving complex fluid flows involving chemical reactions, turbulence and heat transfer, as well as acoustics, solid mechanics and electromagnetics. Releases are scheduled every six months, and the software is distributed under the GPL v3 licence.
OpenFOAM is free, open source computational fluid dynamics software written in C++, owned by the OpenFOAM Foundation and distributed under the General Public Licence. It calculates fluid motion and forces, heat transfer, thermodynamics and chemistry in fluids and solids. It is produced by the core maintenance team at CFD Direct and is used in industry, government research and academia.
OpenRocket is a free model rocket simulator that allows users to design and simulate rockets before building and flying them. It offers a six-degrees-of-freedom flight simulation, CAD-based design, real-time performance data and design optimization. It is written in Java and is cross-platform, with source code available under the GNU GPL.
OpenVSP is an educational resource for documentaries, courses, books, reference material, or self-learning.
Organic Chemistry Portal provides an overview of recent topics, reactions, and information on important chemicals for organic chemists. The site covers name reactions, protective group stability data, synthetic transformations, and article abstracts from organic synthesis journals. It also lists chemicals from suppliers and offers a chemistry tool for estimating molecular properties.
Outerzone is an archive that collects and shares plans of vintage and old-timer flying model airplanes for free. The site states it has 16,962 plans available for free download and does not require a login. It also notes it is currently dealing with a trademark dispute involving a similarly named site.
PC Progress is an educational resource for documentaries, courses, books, reference material, or self-learning.
periodic-table.io is an educational resource for documentaries, courses, books, reference material, or self-learning.
periodic-table.org is an educational resource for documentaries, courses, books, reference material, or self-learning.
The Periodic Table of Videos is a project by video journalist Brady Haran working with chemists at the University of Nottingham. It provides short videos about every element on the periodic table, plus experiments and other chemistry content. All 118 elements have videos, which are being updated.
Phenome10K is an educational resource for documentaries, courses, books, reference material, or self-learning.
Physclips is a multimedia education project offering physics animations and video film clips for introductory physics at different levels. Its current topics include kinematics, mechanics, special relativity, waves, sound, electricity and magnetism. Resources may be freely used by teachers, and students may use the whole package, including interactive tutorials and support pages.
PhysicsClassroom is an educational resource for documentaries, courses, books, reference material, or self-learning.
Planespotters.net is a civil aviation database with 1 million photos and information on 50,000 aircraft. It provides information on registrations, airframes and airlines, along with aviation photos, latest deliveries and photo news.
ProofWiki is an educational resource for documentaries, courses, books, reference material, or self-learning.
