Bookmarks
Cool Websites — September 18, 2026
Security & Privacy
- Mozilla Monitor
- Scans known data breaches for your email address and tells you which ones leaked it, with concrete steps to lock down each account. No sign-up needed to run a scan.
- Privacy.com
- Generates single-use or merchant-locked virtual card numbers so a sketchy checkout page never touches your real card. US-only, but the free tier covers most everyday shopping.
- Guerrilla Mail
- Spins up a disposable inbox in seconds for sign-up forms you don't trust. Messages self-destruct after an hour, and you can reply from the address if you need to.
- Startpage
- Routes your query through Google, strips out every tracker and cookie, and hands you back Google-quality results without building a profile on you in the process.
OSINT & Investigation
- IntelTechniques
- Michael Bazzell's free OSINT tool index: hundreds of hand-picked lookup tools sorted by category (usernames, phone numbers, images) instead of one search box claiming to do everything.
- Social Blade
- Tracks growth history for YouTube, Twitch, TikTok, and Instagram accounts going back years, useful for spotting a fake follower spike or sizing up a channel before a sponsorship deal.
- CachedView
- Pulls a page's cached or archived version from the Wayback Machine, archive.today, and a couple of other sources in one search. Handy when a site goes down or quietly edits a page.
- Onyphe
- Runs weekly scans across the entire internet and lets you search the results, an alternative to Shodan and Censys with its own dataset of exposed devices and services.
Cyber / Hacking Tools
- VulnHub
- Hosts intentionally broken virtual machines you download and try to break into yourself, a hands-on alternative to reading about penetration testing instead of doing it.
- Blue Team Labs Online
- Flips the CTF format around: instead of breaking into systems, you work incident-response scenarios and forensic evidence like an actual SOC analyst on shift.
- Exploit-DB
- OffSec's searchable archive of public exploits and proof-of-concept code, the reference researchers pull up to check whether a CVE actually has working exploit code attached.
- AbuseIPDB
- A crowdsourced blacklist where sysadmins report IPs caught spamming, scanning, or brute-forcing logins, so you can check an address's rap sheet before deciding to block it.
IT & Sysadmin Tools
- tldr pages
- Rewrites man pages as short, example-driven cheat sheets. Type `tldr tar` and get five commands people actually use instead of a wall of flags nobody memorizes.
- WebPageTest
- Runs your site through real browsers on real devices from 40 locations and returns a waterfall chart of exactly what loaded slowly and why. Open-source and free, where several rivals now paywall the useful parts.
- whatsmydns.net
- Checks a DNS record against resolvers in 20-plus countries at once, so after you change a record you can watch how far the update has actually spread instead of guessing and refreshing.
AI Tools
- You.com
- An AI search layer that cites its sources inline and switches between chat, code, and image modes without ever leaving the results page.
- HuggingChat
- Free chat interface for open-source models, currently routing across more than a hundred of them, with an auto mode that picks whichever model actually fits your question.
- Udio
- Type a genre and a lyric idea, get back a full song with vocals in under a minute, a different flavor of AI music generation than the more famous name in this space.
- Julius AI
- Upload a spreadsheet, ask questions about it in plain English, and it writes and runs the analysis code itself, then hands back a chart instead of a formula you'd have to build.
Video & Image Tools
- Descript
- Edits video and audio by editing the transcript: delete a sentence in the text and the matching clip disappears with it. The free plan covers recording, editing, and export.
- Luma AI
- Turns a text prompt or still photo into a short, physically plausible video clip in under a minute. Free generations are watermarked; clean exports start at $30 a month.
- ImgBB
- No-frills image host: drop a file in, get a direct link and BBCode back immediately, no account required for a quick upload.
Developer Tools
- draw.io
- Free diagramming tool for flowcharts, ER diagrams, and network maps that imports files straight from Visio or Lucidchart if you're trying to leave either one behind.
- Can I Use
- Look up any CSS or HTML feature and see exactly which browser versions support it, the tab every front-end developer keeps open somewhere in the background.
- Swagger Editor
- Write an OpenAPI spec on the left, watch the rendered API docs update live on the right, and catch formatting mistakes before they reach your real documentation.
Money & Finance
- Bogleheads Wiki
- Over a thousand pages of investing reference written and maintained by an online community built around low-cost index investing. No ads, no affiliate links, no login wall.
- Portfolio Charts
- Backtests any asset allocation against 56 years of market data and shows the worst-case drawdown, not just the rosy average return everyone likes to quote.
Games
- AI Dungeon
- An open-ended text adventure where an AI improvises the story around whatever you type next. No two playthroughs land the same way.
- Diep.io
- Multiplayer tank arena where you grind shapes for XP and pick an upgrade path at every level, from the creator of Agar.io.
Learning & Reference
- The Feynman Lectures on Physics
- Caltech's free, fully rebuilt online edition of Feynman's original physics lectures, with equations and figures that stay sharp at any zoom instead of a scanned PDF.
- LibreTexts
- A nonprofit library of free, editable college textbooks across 17 subjects, built so professors can remix chapters instead of assigning a $300 book.
Fun / Weird Internet
- You Feel Like Shit
- Walks you through a short sequence of low-effort yes/no questions about water, food, and sleep to figure out what's actually wrong when you can't tell yourself.
- Cat Bounce
- Click and the cats bounce. That's the entire site, and it's somehow still satisfying more than fifteen years in. --- *33 sites this week. Found something broken or have a site to suggest? Reply to the email.*