Practice encrypting and decrypting text using an online library of ciphers

Create your own cipher by combining mathematical operations and encryption protocols

This tool allows users to build an encryption workflow in which the output of one customizable function becomes the input to another, thereby creating undiscovered methods for obscuring information via a series of ciphers.

The science of cryptography, including methods to encrypt data and how to break encryption

Monoalphabetic ciphers use a set of rules to replace each letter with another consistently, making them susceptible to brute force attacks that try every kind of replacement. While more complex ciphers can transform text in less obvious ways, because certain letters are used more often than others, an analysis of letter frequency may reveal patterns that help uncover the rules that make up a cipher.

Watch how the Enigma machine encrypts messages and learn about its critical design flaw

Using settings selected from a series of rotors and a plugboard that let operators swap letters with any of their choosing, the machine lit up the output letter for each letter typed. While this system could generate messages requiring any of 150 quintillion potential keys, the machine's reflector never encrypted a letter as itself, providing an entry point for exploiting the system.

A look at historical ciphers, from the Spartan 'scytale' to the Navajo Code Talkers

From the Greek word for "hidden writing," cryptography in Ancient Greece took the form of batons around which a long strip of leather or parchment was wrapped, after which messages were written. Recipients needed a scytale of the correct width to encircle received ribbons and reveal the message. Members of the Navajo Nation created a code that remained unbroken throughout its use in World War II.

Claude Shannon, for whom Anthropic's AI tools are named, proved the existence of an unbreakable cipher

In the one-time pad approach, the encryption key is randomly generated and of equal length to the plaintext. This randomness ensures that every possible plaintext is equally likely—RBBHN can mean HELLO, SOLVE, CODES, and so on, using a different key—while matching the message and key lengths prevents the appearance of patterns that can be exploited.

How hash functions encrypt stored passwords and can be enhanced with 'salt'

Hash functions convert text into unique, random sets of characters, a process that is computationally expensive and time-consuming to undo. Because hashed outputs for many common passwords are publicly listed, some sites use a salt—additional characters appended to a password—before hashing to produce an output that is not known. When entering a password, it is salted and hashed, then checked against the database for a matching hash before permitting login.

View how AES—the global standard for symmetric encryption—works

Established by the National Institute of Standards and Technology in 2001, the Advanced Encryption Standard transforms plaintext into ciphertext using multiple rounds of processing, including substitution, transposition, and mixing. Larger keys undergo more rounds to produce 16-byte blocks of scrambled data, with 256-bit AES keys taking 3.31 × 10⁵⁶ years to decrypt via brute force.

How end-to-end encryption protects messages, even from service providers

Using symmetric and asymmetric cryptography, data is encrypted on the sender's device before being transmitted across application servers that lack the key needed to decrypt it. The message is not decrypted until it reaches the recipient's device, which uses their private key to recover the plaintext. E2EE's effectiveness has led to its adoption by WhatsApp and Signal.

The dark web protects free speech from censorship and authoritarian oversight

Encrypted networks allow users with internet access anywhere in the world to view blocked content and avoid surveillance when communicating evidence of abuse to independent journalists. The same networks can support democracies by helping activists coordinate protests on dark web forums.

Improve your typing speed by retyping classic literature

Why practice with nonsense letters and syllables when you can retype full books you always wanted to read, from Jane Austen and Sir Arthur Conan Doyle to George Orwell and W.E.B. duBois. And it's free.

Create professional-quality spoken audio from text

Generative AI now makes it possible to create everything from computer-generated written content to beautiful imagery and hyper-realistic videos in seconds from a user’s simple text prompt. Add to that list: High-quality spoken audio, which the AI software company ElevenLabs specializes in. Its natural-sounding speech synthesis and text-to-speech tech can produce human-like speech that mimics a variety of different tones, styles, and accents.

The first compiler to facilitate communication with computers was developed by Grace Hopper

The A-0 program linker automatically translated mathematical symbols into machine-readable binary code. Although it took two years for computer executives to get on board with the idea, the technology was foundational to future programming languages that allowed computers to understand commands written in word-based languages.

Safely explore historic viruses and other malicious software in the Malware Museum

Curated by the Internet Archive, this collection of more than 80 MS-DOS-era pieces of software can be experienced within an emulated environment to see what it would look like to trigger a virus on computers in the 1980s and 90s. Every piece of malware has a version available for download whose malicious capabilities have been removed.

Memes are 'ready-made language'

Internet memes—groups of texts with shared core content, medium, and stance—are what we, as creators and consumers, make of them. Through their seemingly innocuous and irreverent design, these "bite-sized" transmissions have become vehicles of misinformation, conspiracy, propaganda, activism, and subversive messaging.

Explore over 30,000 Olympiad-level math problems

Users can browse questions from 47 countries and 17 languages, sorted by topic across categories that include algebra, geometry, discrete mathematics, and number theory. Each problem is accompanied by at least one solution, with both authored in LaTeX that can be copied over to other platforms.

How to prepare for cyberattacks

An easy-to-digest checklist on the many ways you want protect yourself from a cyberattack before it happens, if it happens, and after it happens.

An archive of anonymous messages people wrote but never sent

The site invites users to submit unsent letters to people, pets, or moments, which are then published anonymously for strangers to read. Every post is moderated, and the design of the site—no likes or replies, just words—feels polished and somber.

A list of MBA jargon, complete with a ‘corporate BS generator’

From the classroom to the boardroom, MBA students hear plenty of corporate jargon in their lifetimes (think: “bandwidth,” “turnkey solution,” “modularize,” and more). This website—a relic from the internet—includes an MBA jargon dictionary and a corporate BS generator tool that creates helpful phrases for office life, like “incubate synergistic e-markets.”

'The Republic of Letters' was an analog internet for the Enlightenment.

The virtual intellectual society exchanged tens of thousands of letters and spanned several continents. Some of its most avid correspondents were Voltaire, Benjamin Franklin, and Saint Ignatius of Loyola, founder of the Jesuits.

Type out a tone and play it back with this fun game

Compose an original piece of music from your phone or desktop with this simple, super fun interface: Just start typing, discover the various sounds associated with each key or letter, and then press play. Go back, tweak, delete, and revise to your...

An explanation of TCP/IP, which helps transmit data across the internet like a club sandwich

The system consists of several layers—application, transport, internet, and network—each responsible for specific tasks. These include interacting with a web browser, checking for errors, sending packets of data across various networks to avoid congestion on their way to a destination address, and managing the transmission of information across hardware, such as an Ethernet cable.

Can you save Britain from the Nazis by carefully sharing secrets with America?

Find out in this 20-minute interactive graphic novel based on true events from World War II.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

Translating ‘Harry Potter’ required creativity across 60+ languages

This Vox video explores how translators adapted JK Rowling’s wordplay, invented spells, and cultural references—reimagining names and magical terms while attempting to preserve humor, rhythm, and meaning for readers around the world.

Princeton University offers a free online bitcoin course

Want to understand bitcoin and cryptocurrencies? A free online course from Princeton University unpacks the details of bitcoin, from how it works to what distinguishes it from other currencies, to the security and anonymity associated with its use. Explore explainer videos, or take the course as a series of lessons.

Google Search includes over 50 Easter eggs hidden behind specific search terms

Some queries—besides providing search results—trigger additional effects on the site, including tilting the page after searching for "askew," having the page perform dance moves to the song after searching for "[cha-cha slide]," and the ability to play a version of block breaker after searching for "Atari breakout."

Elk Cloner, the first computer virus to spread in public, was written as a practical joke by Richard Skrenta, a Pittsburgh high school student.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

The term 'algorithm' originated from the Latinized name of al-Khwārizmī, a 9th-century mathematician whose works introduced Arabic numerals and the decimal-based numeral system to Europe and whose treatise 'Al-Jabr' gave algebra its name.

Search a massive database of over 4 decades of clues from the TV quiz show 'Jeopardy!'

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

See these 16 pieces of art evoking phobias of snakes, flying, spiders, and more. 

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

Explore chaos in this simulation of two double pendulums, where small differences in the release angles produce wildly different outcomes.

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

The idea for the Federal Reserve was conceived in secret in 1910—with bankers donning duck hunt gear for disguise while traveling to a remote country club on Georgia's Jekyll Island

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

Use this tool to calculate the dollar value of your parental mental load, from meal planning to coordinating after-school care, then see resources that help generate solutions.

During the French Revolution, a botanist's letter asking about "dear Rhus" (poison ivy) was intercepted, leading authorities to suspect he was conspiring with the Russians.

Hear 50 years of iconic hip-hop samples, the genre's foundational looped tracks

Mid-century modern graphic designers, known for their bright colors and bold lines in advertising, also found success with children's books.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

Prince's sexually explicit 1984 track 'Darling Nikki' attracted the ire of the Parents Music Resource Center, an advocacy group that inspired the Parental Advisory sticker, even though the song ends with a Christian message.

Learn how to read a prospectus, the juicy document that any company must file with the SEC before going public.

Explore a list of the 100 best novels of all time, compiled by some of the world's best living writers, including Salman Rushdie, Stephen King, and Jennifer Egan.

Explore the archaeological treasures of Pompeii, the city buried under volcanic ash when Mount Vesuvius erupted in 79 CE.

Hotels in Cannes, the glamorous city on the French Riviera, hire hawks to ward off seagulls during the city's famous film festival.

The American Society of Civil Engineers' infrastructure report card gave the US a C in 2025, its highest grade since the project launched in 1998.