Thirty-five corners of the internet that mostly don't come up in casual conversation — a JPEG forensics lab, a Windows treemap that's outlived three redesigns of Windows itself, and a vocal tract you can drag with your mouse.
Point it at any public URL and it scores the site's security headers — CSP, HSTS, cookie flags — against real best practices, then explains exactly what's missing. Free, no signup, and it's graded more than 47 million pages since 2016.
Reads the terms of service you never do and grades a company from A to E based on the specific clauses buried inside: data retention windows, arbitration traps, tracking consent. Volunteer-run since 2012, with a browser extension that flags a site's grade before you click "I agree."
Lets you cryptographically prove that your Mastodon account, your GitHub profile, and your personal site all belong to the same person, using a PGP key instead of a corporate identity provider you have to trust. Open source, funded by an NGI Zero grant, no company sitting in the middle.
Stores your encrypted messages on your phone instead of on a server, and can sync them over Bluetooth or Wi-Fi when the internet is down or blocked entirely. The project is in maintenance mode now, but the Android app still works and there's no company to subpoena for your data.
Uploads run through Error Level Analysis, which flags patches of a JPEG with inconsistent compression history — often, though not always, a sign someone pasted something in. It won't hand you a verdict, just the raw evidence and full EXIF data to draw your own conclusion.
Aggregates official company registration filings from more than 140 government jurisdictions, so tracing a shell company's actual owners or checking that a vendor is a real registered business takes one search instead of a dozen. Basic lookups are free; bulk exports and API access cost money.
Cross-references over a billion leaked documents, corporate registries, sanctions lists, and court records across 180-plus countries into one searchable graph, built by investigative journalists who needed to trace money and people faster than governments do. Browsing is free; exporting results needs a free account.
Ten million-plus federal and state court opinions, plus PACER filings mirrored for free through its RECAP Archive — the same records Westlaw charges hundreds of dollars a month for. Run by the nonprofit Free Law Project, updated daily, with free alerts when a case gets a new filing.
Catalogs the ordinary Unix binaries — sudo, find, vim, and dozens more — that can be twisted into a privilege escalation or a shell if a system is misconfigured. Pentesters use it as a lookup table mid-assessment; defenders use the same list to know what to lock down.
The Windows sibling of GTFOBins: a searchable database of legitimate system binaries and scripts that attackers repurpose for execution or persistence, each entry mapped to a MITRE ATT&CK technique. Blue teams lean on it constantly when writing detection rules.
Detonates a submitted malware sample inside a configurable sandbox and extracts the config data for known malware families automatically. Free for individual samples; the API and bulk submission tiers are where it starts charging.
The routing "looking glass" network engineers actually reach for — BGP prefix and peer reports, live traceroute, WHOIS, all keyed to any ASN, prefix, or IP on the internet. No account, no catch, just the data.
Runs your scheduled HTTP requests on someone else's server instead of yours, from once a minute to once a year, and emails you when a job fails. Donation-funded, completely free, one less cron daemon to babysit.
A grab-bag of network utilities that somehow still works after all these years: port-forwarding tester, traceroute plotted on an actual map, reverse IP domain lookup. No account, no clutter, still one of the fastest ways to check if a port is actually open from outside your network.
Feed it one paper and it builds a citation and co-authorship graph across 310 million indexed works, surfacing related research a keyword search would never catch. People call it "Spotify for papers" because it works the same way — you follow the recommendations, not the search bar.
A neural network trained on font pairings suggests combinations you'd never think to try, and you can lock the one you like while it keeps generating options for the rest. No signup, results in under a second.
Upload a PDF and ask it questions directly — the answers link back to the exact page they came from, so you're not trusting a black box. Free tier caps out at two documents a day with no account required.
Turns a regular expression into a railroad diagram, so the branching logic in that pattern you inherited actually becomes visible instead of staying symbol soup. Open source, exports as SVG, generates a permalink you can drop in a code review comment.
A daily challenge where you recreate a target image using the shortest CSS and HTML you can write, scored purely on character count. Four hundred thousand people play it, and it teaches shorthand properties faster than any tutorial because you feel every wasted byte.
Drag the control points on a curve and watch a CSS animation play back at the timing you're actually building, then copy the cubic-bezier() value straight into your stylesheet. Built by Lea Verou, with a library of saved curves and shareable permalinks.
Renders a drive as a treemap where rectangle size is file size and color is file type, so the thing eating 40GB you can't account for jumps out visually instead of hiding three folders deep. Open source, GPLv2, unchanged in spirit since it first showed up in the 2000s.
Sits quietly in the background and gives Windows an instant file search and app launcher, then injects that same search bar directly into native Open/Save dialogs — the part of Windows that never got faster on its own. The core tool is free; Listary Pro adds extras most people won't miss.
Converts video from almost any source format into H.264 or H.265 using device presets, so you don't have to learn encoder settings just to get a file that plays on your phone. Open source, cross-platform, and it's been the default answer to "how do I shrink this video" for over a decade.
A free video editor built on FFmpeg that lets you mix resolutions and frame rates on the same timeline without pre-converting anything first. Handles 4K and even Blackmagic capture cards, all open source.
Digital painting software with a stabilizer that smooths out shaky linework and a real animation timeline built in, aimed at illustrators rather than photo editors. Free, GPL-licensed, and it's become the default Procreate alternative for people who don't own an iPad.
Instead of forcing people to guess your free slots from a grid, it overlays your availability on top of theirs so they see the overlap directly. Free tier available, and it's the rare scheduling tool that makes the other person's calendar part of the picture.
One canvas for flowcharts, mind maps, wireframes, and docs, built for sketching an idea fast rather than producing a polished diagram. Free tier covers a surprising amount before you hit a wall.
An AirDrop clone that works across any OS — open it on two devices on the same network and drag a file over, no app install, no account. Open source, and the thing to bookmark for the next time you need to get a file off your phone onto a Windows laptop in ten seconds.
Splits a group trip's expenses and works out who owes whom in the fewest possible transactions, instead of everyone Venmoing everyone else in a circle. Free, and it's the app people quietly recommend after the first group trip that ended in a spreadsheet argument.
Runs your retirement withdrawal plan against more than a century of real historical market data instead of one optimistic average, and shows exactly which years it would have failed. Free, no account, and the parameters live in the URL so you can share a specific scenario with a link.
Tracks balances and expiration dates across 600-plus airline, hotel, and credit card loyalty programs in one dashboard and warns you before points quietly expire. Free tier covers unlimited accounts with a few feature caps; it's been running since 2004, which says something in a space full of dead startups.
Drag your mouse across a cross-section diagram of a mouth and throat and it physically simulates the airflow to produce actual speech sounds — vowels, growls, noises no synthesizer preset would ever give you. It's not a recording, it's a real-time model of how a vocal tract works, which makes it genuinely strange to play with.
One person's collection of roughly 150 vintage machines, photographed and specced out — but the real find is the archive of original period advertisements, a time capsule of how companies pitched a Commodore 64 or a TRS-80 to 1980s households.
A complete linear algebra textbook, free, where every diagram is a live figure you can drag instead of a static image — watch a vector actually rotate instead of imagining it. Written by three graphics researchers who use this math in their day jobs.
Walks through writing GLSL fragment shaders with editable code sitting right next to each explanation, so the visual output changes as you type instead of after a separate compile step. Translated into 13-plus languages, and one of the only gentle on-ramps to a topic usually taught by throwing math at you.