Cool Websites

A fully open-source, end-to-end encrypted password manager with apps on every platform (browser extensions, iOS, Android, desktop, CLI). The free tier covers unlimited passwords across unlimited devices — no paywall on the core features that matter. Organizations can self-host the entire server, and independent security audits confirm the code matches what they claim.

Tuta (formerly Tutanota) is a free, end-to-end encrypted email service built in Germany with GDPR compliance baked in — your messages, calendar, and contacts are all encrypted client-side so even Tuta can't read them. It's powered by renewable energy, completely ad-free, and now uses quantum-safe encryption algorithms to future-proof against next-generation cryptographic attacks.

An open, volunteer-maintained project that grades privacy policies on a 0–10 scale across 17 criteria — covering data sale, breach notification, data deletion rights, tracking, and more — and presents the results as simple letter grades with cited quotes from the policy itself. A quick way to find out whether that "free" app is actually selling your data before you hand it over.

Censys continuously scans the entire internet and maintains a real-time map of every exposed host, certificate, and service — covering IPv4, IPv6, and domain names. Security teams use it to audit their own attack surface; researchers use it to track certificate issuance, spot compromised hosts, and study how quickly patches propagate globally. A free community tier provides meaningful access for personal research and small-scale auditing.

A search engine for web page source code — enter any HTML snippet, JavaScript fragment, tracking pixel ID, or CSS class and PublicWWW returns all public websites that contain it. Invaluable for finding every site running a specific ad network, a known-vulnerable library version, a particular analytics ID, or a widget fingerprint. Used by marketers, security researchers, and competitive intelligence analysts; free tier allows limited daily searches.

An AI-powered face search engine: upload a photo of a person and PimEyes scans the open web for other images containing the same face using computer vision rather than metadata. Security researchers use it to demonstrate how much of your face is indexed online; journalists use it to identify people in untagged photos. The free tier shows search results; full source URLs require a paid plan. Use responsibly — this is a tool for understanding your own exposure, not tracking others.

A cybersecurity training platform with 1,500+ hands-on hacking labs spanning web exploitation, network penetration, active directory, reverse engineering, forensics, and AI security. Labs run in cloud-hosted virtual environments — no local setup required — and progress through structured career paths with industry-recognized certifications. The free tier gives access to a meaningful set of labs and the vibrant community; Pro unlocks the full catalog.

Seven hundred-plus labs built around real CVEs and exploitation patterns, with a strong emphasis on source-code review alongside hands-on exploitation — teaching you to find vulnerabilities the way a developer introduced them, not just the way a scanner finds them. Every exercise includes a badge you earn by solving it. The free tier covers introductory exercises; Pro ($199/year) unlocks the full library and video walkthroughs.

A free, community-built cybersecurity challenge platform with 835,000+ users and 16+ years of history. Challenges span 13 categories — web app security, network capture analysis, cryptography, forensics, reverse engineering, steganography, and more — and range from complete beginner to research-level difficulty. No walled garden: all challenges are free, no subscription needed, and the community publishes solution write-ups once you complete each stage.

A free online library of over 10 million PDF user manuals for 141,000+ brands — search for any appliance, camera, router, power tool, or electronic device and you'll almost certainly find the official manual, wiring diagram, or service guide. No registration required to read online; download access is free after a quick email verification. The go-to resource for when you inherit hardware with no documentation or need the spec sheet for a device the manufacturer has discontinued.

A crowdsourced real-time outage tracker: when Slack, GitHub, Cloudflare, your bank, or any major service goes down, Downdetector aggregates user reports into an outage graph within minutes — usually faster than the service's own status page. Visit downdetector.com/status/[service-name] for any major platform and get an instant crowd-sourced pulse on whether the problem is just you or everyone. Free, no account needed.

Netflix's dead-simple, ad-free internet speed test — one large number on a clean page, no bloat. Because it measures download speed using Netflix's own CDN infrastructure distributed worldwide, it gives a real-world proxy for how fast streaming-class traffic flows on your connection rather than synthetic lab conditions. Click "Show more info" for upload speed, ping, and latency details. Works on any device in any browser.

An AI-powered presentation and document builder that turns a one-sentence topic or a rough outline into a polished, visually designed slide deck in seconds. Choose a theme, watch it generate slides with headers, bullet points, images, and charts pre-placed, then edit freely. Unlike most AI tools that spit out plain text, Gamma understands layout — it produces things that look ready to present, not ready to format. Free tier includes 400 AI generation credits; no watermark on public links.

An AI-powered answer engine that searches the web in real time, reads multiple sources simultaneously, and synthesizes a single cited answer — with inline footnotes you can click to verify each claim. Unlike a chatbot trained on a fixed knowledge cutoff, Perplexity's answers are grounded in live search results, making it dramatically better for anything recent or fact-sensitive. The free tier is genuinely capable; Pro adds deeper research modes and access to more powerful models.

A creative AI suite built around a real-time generation canvas: drag sliders, tweak prompts, or sketch a rough shape and watch the image update live as you adjust — zero waiting for a generation to complete. Supports 1,000+ visual styles across 20 models and can generate images natively in 4K. The free tier provides 100 compute units daily, enough for real experimentation. Also includes AI video generation, image upscaling, and background enhancement tools.

An AI-powered stem separator that splits any audio track or video file into vocals, instrumental, bass, drums, piano, electric guitar, acoustic guitar, and synthesizer — as separate downloadable files. Feed it a song, a podcast recording, or a film clip and get clean isolated stems without the phasing artifacts that plagued older splitter tools. The free Starter tier lets you preview results before committing to a paid download.

A web-based AI video editor that needs no installation — upload footage, trim and arrange clips, auto-generate captions, remove backgrounds, add subtitles in 70+ languages, and export finished video, all from a browser tab. The AI "Studio" mode generates complete short-form videos from a text prompt. Free tier covers most basic editing needs and leaves no watermark on exports under five minutes; paid plans unlock longer exports and priority processing.

A free browser-based GUI for SVGO — the industry-standard SVG optimizer — that lets you fine-tune dozens of compression settings with live before/after preview and byte-count feedback. Paste or drag in an SVG exported from Figma or Illustrator (bloated with metadata, editor IDs, and redundant paths) and watch it shrink 40–70% with zero visible quality loss. Everything runs client-side; nothing is uploaded. An essential bookmark for anyone who ships SVG assets to the web.

A unified, offline-capable documentation browser for 100+ developer technologies: JavaScript, Python, Go, Rust, React, Node, Docker, PostgreSQL, Ruby, PHP, and dozens more — all searchable with one fuzzy-search bar, with instant keyboard navigation and a dark theme. Enable offline mode in the settings and the full documentation set for any technology downloads to your browser for use without a connection. Open source, ad-free, and run by freeCodeCamp.

Paste any JSON (or JSON Schema, TypeScript, GraphQL, or YAML) on the left and Quicktype instantly generates type-safe data models and parsing code on the right — for Swift, Kotlin, TypeScript, C#, Python, Go, Java, Rust, and 15+ other languages. Instead of hand-writing struct definitions every time you integrate a new API, you get correct, idiomatic code in seconds. Runs in the browser with no account needed; also available as a CLI and VS Code extension.

Software licenses summarized in plain English with color-coded "Can / Cannot / Must" tables — covering GPL, MIT, Apache, BSD, LGPL, AGPL, Creative Commons, and 100+ others. Before you ship code using an open-source library or integrate a dependency, drop the license name here and get a 30-second answer on whether you can use it in a commercial product, whether you must disclose source, and what attribution you owe. Backed by FOSSA; free to use.

A free and open-source screenshot and screen recording tool for Windows with 18+ years of continuous development — capture regions, windows, or full screens; record screen as GIF or MP4; annotate and blur PII in one pass; and automatically upload to any of 80+ file hosts or your own server. Zero ads, zero nag screens, and a scripting system that automates your entire "capture → annotate → upload → copy link" workflow in one keyboard shortcut.

A free Windows file search tool that indexes every file and folder on your drives in seconds and then returns results in real time as you type — no waiting, no spinner. The standard Windows search requires background indexing and still often misses files; Everything finds any filename on a 2 TB drive before you finish typing the third character. Tiny, portable, requires no installation.

A free, open-source customization marketplace for Windows — install community-created mods (each published as reviewed source code) that modify the taskbar, Start menu, File Explorer, system tray, and other shell components at a low level. Unlike registry hacks, each mod ships with a user-friendly settings panel; unlike themes, the changes run live without replacing any system files and can be toggled off instantly. Actively maintained with hundreds of available mods for Windows 10 and 11.

A local-first, open-source personal finance app using envelope budgeting — you allocate income into spending categories at the start of each month and track how each fills up as you log transactions. All data lives on your device (or your own server) with optional end-to-end encrypted sync; nothing is stored in Actual's cloud. Available as a web app, desktop app, and mobile companion; completely free and self-hostable.

A self-hosted, open-source newsletter and mailing list manager that handles list management, template design, campaign scheduling, subscriber segmentation, bounce processing, analytics, and transactional emails — everything Mailchimp or Sendinblue charge $30–100/month for — at zero cost if you run it on your own server with your own SMTP. Single binary deployable in minutes; supports unlimited lists and subscribers.

A free, open-source real-time monitoring agent that deploys in under a minute and immediately begins graphing 2,000+ system and application metrics at per-second granularity — CPU, RAM, disk I/O, network, Docker containers, Kubernetes pods, databases, web servers, and more. Machine learning runs on-device to detect anomalies without cloud dependency. The community tier is fully free; the managed cloud dashboard makes multi-host fleets manageable.

Write a letter to yourself, pick a delivery date between one month and 30 years from now, and FutureMe emails it on that exact day. Completely free, no account required for basic use. People use it to leave notes for their future selves after big life decisions, seal time capsule letters for milestone birthdays, set goal reminders, or simply check in on the person they were. The public gallery of anonymized letters — spanning years of self-reflection — is its own quietly profound read.

A free time-tracking tool with apps for web, macOS, Windows, Linux, iOS, and Android — start a timer with one click, tag it to a project and client, and let Toggl do the math. The free plan supports unlimited time entries, unlimited projects, and the core reports; paid tiers add billing rates, required fields, and team management. Browser extensions for Chrome and Firefox add start/stop buttons inside Jira, GitHub, Asana, and 100+ other apps so you never leave your workflow to track time.

A collaborative note-taking app built around atomic notecards rather than long scrolling documents — each note stays focused and brief, then cards link together into a knowledge graph you can explore visually. Real-time collaboration lets multiple people edit the same card simultaneously; an AI assistant helps you draft, expand, or summarize cards. The free plan includes 100 cards (expandable via referrals), and the interface is deliberately instant — no loading screens, no formatting sidebars to fight.

Move your mouse anywhere on the page and the site finds a photo from its massive library where someone is pointing exactly at your cursor position. That's the entire website. No login, no ads, no other content — just thousands of meticulously tagged photographs of people pointing in every possible direction. Delightfully absurd, surprisingly hypnotic, and genuinely impressive as a database engineering feat.

People around the world have uploaded short looping videos of the view from their windows — a rainy street in Seoul, a sunny courtyard in Lisbon, a foggy forest in Vermont — and WindowSwap plays a random one whenever you open it. "The calmest place on the internet." No interaction required, no goal, no account; just press Escape if you want a new view. Perfect for a background tab when your own surroundings feel stale.

A 2004 collaborative art project that still works perfectly: a painting that zooms infinitely, looping forever through a surreal dreamscape of creatures, ruins, forests, and cities — each panel painted by a different artist who had to blend seamlessly into their neighbors. Stare at it long enough and you realize every image contains the entire painting recursively. One of the oldest and most satisfying things on the internet. Runs in pure HTML5; no plugins needed.

A daily geography puzzle where you're shown the silhouette of a mystery country and get six guesses. After each wrong guess you receive the distance from your guess to the target (in km), a directional arrow, and a proximity percentage — so each attempt gives you new information. 250 countries and territories in rotation; the puzzle resets at midnight UTC. Simple to play, genuinely educational, and substantially harder than you expect from the first round.

A trivia quiz platform with hundreds of thousands of user-created quizzes across every conceivable category: name all 50 US state capitals in four minutes, list every country in Africa, identify logos by color alone, recall the opening line of Harry Potter chapters, complete song lyrics, name Premier League top scorers by decade. Infinite variety, genuinely competitive leaderboards, and a nightly live trivia event. Free to play with account; many quizzes work without logging in.

An incremental browser game where you start as an AI given one objective: make paperclips. Click to make your first one, sell it, reinvest in better machines — and then things escalate dramatically. The entire arc unfolds across three distinct phases, each more mind-bending than the last, and the whole thing takes 4–8 hours without leaving your browser. Created by Frank Lantz as a playable illustration of Nick Bostrom's "paperclip maximizer" AI alignment thought experiment — one of the most efficient ways to viscerally understand why AI goal specification is hard.