Quantum’s (a.k.a. Guanzhong Chen) blog about coding, security, and other computer technology.

Practice problem solving and compete against others on the DMOJ, a modern contest platform and archive of programming problems.

Instant offline access to 200+ API documentation sets, code snippets, and cheat sheets. Features MCP support for AI integration.

Fast, offline, and free documentation browser for developers. Search 100+ docs in one web app: HTML, CSS, JavaScript, PHP, Ruby, Python, Go, C, C++…

No Internet - no problem. Download and store Wikipedia on your phone or computer, along with hundreds of other education websites.

WordyWordy takes text that's dropped on it and shows it. One word at a time. As slow as you want.

mscgen_js - turns text into sequence charts. On line message sequence chart renderer for charts written in mscgen, msgenny or xù.

AzuraCast is a free and open-source, self-hosted web radio management suite.

Free domain research tool to discover hosts related to a domain. Find visible hosts from the attackers perspective for Red and Blue Teams.

The Pudding explains ideas with visual essays.

The Best Ping+MTR combination Ever, plus TCP port checker and DNS diagnostics with dig, plus real time BGP looking glass from multiple locations.

Intelligence X is a search engine and data archive. Search Tor, I2P, data leaks and the public web by email, domain, IP, CIDR, Bitcoin address and more.

KiwiSDR, WebSDR, and Web-888 map for internet shortwave
receivers around the world. Click to listen in your web browser. Tune the BBC, Amateur radio,
aero and military communications or regular AM radio signals via internet stream. Professional
quality radio…

On the Internet, network devices exchange routes via a protocol called BGP (Border Gateway Protocol). Unfortunately, issues with BGP have led to malicious actors being able to hijack and misconfigure devices leading to security problems which have the potential…

Short and simple video lessons that start from scratch. Tools and thoughts that might make your professional life more enjoyable.

Self-hosted news, content, updates, launches, events, and more