Week 42, 2026

A classic guide that groups and explains Python's special (dunder) methods such as __init__, __getattr__ and __enter__ with examples. in Programming Languages →

A collection of surprising and counter-intuitive Python behaviours, each as a short snippet with an explanation. in Programming Languages →

Long-maintained, free and witty guides to C and network (socket) programming, offered as HTML, PDF and print. in C, C++ & Rust →

The well-known infographic with explanation of the CPU clock-cycle cost of operations such as addition, memory access… in C, C++ & Rust →

A step-by-step tutorial that goes from a bootloader up to a kernel, one short folder per step. in C, C++ & Rust →

A free book on writing a simple x86 operating system from scratch: booting, memory, interrupts, system calls. in C, C++ & Rust →

A one-page tutorial on writing a virtual machine for the LC-3 architecture in C, ending with real LC-3 programs running. in C, C++ & Rust →

A checklist of items to verify before launching a web page across HTML, CSS, JS, accessibility, performance and SEO, with priority labels. in Web & Frontend →

Mozilla's recommended security headers and settings for websites: CSP, HSTS, cookie flags, CORS, SRI. in Web & Frontend →

A form-driven generator that builds a ready NGINX config from domain, PHP/Node, security and performance options. in Web & Frontend →

An open-source map stack that serves a world basemap as a single PMTiles file; the file sits on plain storage such as… in Web & Frontend →

A community-run accessibility site with a plain checklist based on WCAG, articles and lists of tools and resources. in Web & Frontend →

WebAIM’s accessibility evaluation tool; given an address, or through its browser extension, it overlays errors, alerts… in Web & Frontend →

The W3C’s “How to Meet WCAG” page: every success criterion, its level (A, AA, AAA), the techniques that satisfy it and… in Web & Frontend →

The official site of the WebAssembly standard: the specifications, an introduction to the concepts and a feature table… in Web & Frontend →

An open-source linter that scans a site for accessibility, speed, security and compatibility problems and explains each… in Web & Frontend →

A small reference site that explains CORS with copy-paste configurations for dozens of servers and frameworks (Apache, nginx, Node, IIS and more). in Backend, API & System Design →

A readable alternative to curl that sends HTTP requests with coloured JSON output and a simple syntax. in Backend, API & System Design →

A command-line tool that runs HTTP requests and checks their responses (status, JSONPath, XPath, headers) from plain-text files, usable as tests in CI. in Backend, API & System Design →

The classic article on how one server can handle ten thousand concurrent connections (select/poll, epoll, threading models, kernel support). in Backend, API & System Design →

A WebAssembly runtime that lets you choose between several compiler back ends (Singlepass, Cranelift, LLVM), with a… in Backend, API & System Design →

The Bytecode Alliance’s runtime for running WebAssembly outside the browser; written in Rust, compiling with Cranelift… in Backend, API & System Design →

Searchable documentation for every postgresql.conf parameter, with version differences, defaults and community recommendations. in Databases →

An interactive online book that teaches SQL through exercises run in the browser against one real dataset. in Databases →

A list of target sites and APIs for practising test automation: demo shops, forms, trap-laden pages and fake APIs, grouped by kind. in Testing & QA →

A test site that serves subdomains with deliberately broken TLS setups (expired, self-signed, wrong host and so on). in Testing & QA →

A French test site that grades the TLS setup of HTTPS, SMTP and XMPP servers by cipher suite, certificate and key exchange. in Testing & QA →

A Google tool that flags bypassable rules (unsafe-inline, broad wildcards, missing directives) when you paste in a Content-Security-Policy header. in Testing & QA →

A scanner that gathers a domain's DNS, email (SPF/DKIM/DMARC), TLS and web-header security into one report. in Testing & QA →

A page that grades your browser's TLS client setup (version, cipher suites, known weaknesses). in Testing & QA →

Mozilla's in-browser checker that scores a site's headers, cookies and TLS settings against security best practice; it now lives inside MDN. in Testing & QA →

A browser-based scan that grades a site's HTTP response headers (CSP, HSTS, X-Frame-Options, Permissions-Policy and so… in Testing & QA →

A compilation of static analysis tools, linters and formatters grouped by language and format (formerly awesome-static-analysis). in Testing & QA →

A list for geographic information systems: cartographic tools, geoanalysis libraries, data sources and communities. in Data Science & ML →

An open-source tool, born at Uber, for visualising large location datasets (millions of points, trips, grids) layer by layer in the browser. in Data Science & ML →

Interactive WebGL map clustering subreddits by shared commenters (2020-21 comments). in Data Science & ML →

X-lab's analysis platform publishing open-source health metrics derived from GitHub activity (OpenRank, activity, contributors). in Data Science & ML →

A web front end for querying OpenStreetMap data through the Overpass API; it shows the result on a map, downloads it as… in Data Science & ML →

An open-source desktop GIS for Windows, macOS and Linux; it reads and analyses shapefile, GeoPackage, PostGIS and… in Data Science & ML →

The EFF client that obtains and renews Let's Encrypt certificates; the site gives exact commands once you pick your web server and OS. in DevOps & Infrastructure →

Brendan Gregg's page on the flame graph visualisation: how to read one, the CPU/memory/off-CPU variants, generation tools and talks. in DevOps & Infrastructure →

A local AWS emulator for development and CI that needs no account or token; the AWS SDK, CLI and Terraform simply point at port 4566. in DevOps & Infrastructure →

Hands-on labs and challenges teaching Linux, containers, Kubernetes and networking in real VMs inside the browser. in DevOps & Infrastructure →

A checklist to review before running Kubernetes in production: resource limits, health checks, networking, security and observability. in DevOps & Infrastructure →

Kelsey Hightower's guide to bootstrapping a Kubernetes cluster by hand, component by component, without automation. in DevOps & Infrastructure →

A collection of real post-mortems of outages and system failures published by companies. in DevOps & Infrastructure →

A Mozilla article that uses cartoons to explain why DNS is a privacy problem and how DoH changes it. in Networking & Sysadmin →

A list of eBPF projects, articles and tools, with compilers, tracing and networking (XDP) under separate headings. in Networking & Sysadmin →

A service that bridges websites, the fediverse (Mastodon etc.) and Bluesky/AT Protocol so accounts can follow and reply across networks. in Networking & Sysadmin →

A reference site that lists every TLS cipher suite searchably, with IANA and OpenSSL names, a security rating… in Networking & Sysadmin →

The site for the standard command-line tool for transferring data with URLs and for the libcurl library; it has the… in Networking & Sysadmin →

Send a test email to the temporary address it gives you and it reports SPF, DKIM and SpamAssassin scores. in Networking & Sysadmin →

A research site showing DNS records, sites sharing an IP, mail/whois data and history for a domain, IP or autonomous-system number. in Networking & Sysadmin →

Verisign's tool that validates a domain's DNSSEC chain of trust from the root down and shows where it breaks. in Networking & Sysadmin →

A quick checker for a domain's DNS and mail (MX) setup that lists errors and warnings point by point. in Networking & Sysadmin →

A Cloudflare page that tests from your browser whether your ISP filters invalid BGP routes (RPKI). in Networking & Sysadmin →

Looks up an IP or domain in hundreds of DNS blocklists (RBLs) at once. in Networking & Sysadmin →

An email and DNS diagnostic that runs MX, DNS, blacklist, SPF, DMARC, ping and port lookups from a single box. in Networking & Sysadmin →

A wildcard DNS service that resolves names like 10.0.0.1.nip.io to the IP embedded in them, so you can reach a local or… in Networking & Sysadmin →

A map rendering power lines, plants, oil/gas pipelines and telecom infrastructure from OpenStreetMap data. in Networking & Sysadmin →

The official site of the TLS/SSL and general-purpose cryptography library and the openssl command-line tool; command… in Networking & Sysadmin →

A step-by-step guide to building a root and intermediate certificate authority with OpenSSL, signing certificates and publishing revocation lists. in Networking & Sysadmin →

RIPE NCC's network of thousands of small probes that run ping, traceroute and DNS measurements from around the world. in Networking & Sysadmin →

An interactive Python library for forging, sending, capturing and decoding packets; the site hosts docs and examples. in Networking & Sysadmin →

TeleGeography's interactive map of the world's submarine internet cables, landing points and owners. in Networking & Sysadmin →

A toolbox of dozens of DNS and domain queries in one place: reverse IP lookup, DNS history, whois, a port scanner, domain-to-IP mapping. in Networking & Sysadmin →

A checker that runs a domain's DNS setup (delegation, SOA, DNSSEC, nameserver consistency) through dozens of tests; the… in Networking & Sysadmin →

The official home of the wiki software that runs Wikipedia, with installation, configuration, extension and API documentation. in Self-Hosting & Personal Cloud →

A large guide to hosting your own services (home and cloud), packed with software and tool links. in Self-Hosting & Personal Cloud →

A self-hostable chat platform reimplementing Discord's backend and frontend. in Self-Hosting & Personal Cloud →

Catalogue of apps installable in one click on YunoHost, graded by packaging quality and upkeep. in Self-Hosting & Personal Cloud →

A suite of tests, one tab each, showing what your browser leaks (IP/WebRTC, canvas and font fingerprints, JavaScript, geolocation, client hints). in Privacy & Personal Security →

A categorised personal digital-security checklist of 300+ items, each with recommended tools and settings. in Privacy & Personal Security →

The free implementation of the OpenPGP standard, a command-line tool for encrypting, signing and key management. in Privacy & Personal Security →

Turkey’s data-protection authority: Law No. in Privacy & Personal Security →

A community guide to hardening macOS step by step: FileVault, firewall, DNS, VPN and app permissions. in Privacy & Personal Security →

A catalogue of free, privacy-respecting alternatives to surveillance-prone services, organised by platform and category. in Privacy & Personal Security →

A form that generates the /.well-known/security.txt file (RFC 9116) telling security researchers where to report a… in Privacy & Personal Security →

The Electronic Frontier Foundation's guide to protecting communications and devices against surveillance, from building… in Privacy & Personal Security →

Ghostery's monthly measurements of how widespread tracking is across websites and tracker companies; you can look up which trackers run on which site. in Privacy & Personal Security →

A wiki that gathers application security resources (guides, tools, checklists, training) in one place. in Offence, Defence & OSINT →

A list for security research on IoT, embedded, industrial and automotive systems, gathering hardware attacks, wireless… in Offence, Defence & OSINT →

A year-by-year archive of cybersecurity blog posts, write-ups and papers, with entries up to 2026. in Offence, Defence & OSINT →

A security-oriented resource list on industrial network protocols such as Modbus, S7 and OPC UA, with a page and dataset per protocol. in Offence, Defence & OSINT →

A profiler that identifies the CMS, analytics, hosting and JavaScript technologies a site uses from its address. in Offence, Defence & OSINT →

Passive reconnaissance for a domain: subdomains, DNS records and a host map, with no scan of the target itself. in Offence, Defence & OSINT →

Offensive Security's searchable archive of published exploits and vulnerability write-ups, indexed by CVE. in Offence, Defence & OSINT →

The NSA's open source reverse engineering framework with disassembler, decompiler and scripting. in Offence, Defence & OSINT →

A list of Unix binaries that can be abused to escape restricted shells, escalate privileges or read files. in Offence, Defence & OSINT →

A numbered collection of XSS vectors arising from HTML5 and browser quirks, each listing the browsers it works in. in Offence, Defence & OSINT →

Tools, protocol notes, sample pcaps, configurations and guides for industrial control system (ICS/SCADA) security. in Offence, Defence & OSINT →

The wiki of Kicksecure, a hardened Debian derivative, covering system hardening, kernel and browser settings, Tor and password management step by step. in Offence, Defence & OSINT →

An open source proxy that intercepts, inspects, modifies and replays HTTP(S) traffic, with terminal, web and scripting interfaces. in Offence, Defence & OSINT →

A GitBook site gathering OSINT web-resource and tool lists plus blog posts, with a separate page of newly added resources per year. in Offence, Defence & OSINT →

An OSINT guide of 450+ tools, methods and ethics/legal notes across 35 sections, which also publishes a link-audit report. in Offence, Defence & OSINT →

The OWASP guide to security testing Android and iOS apps, with test cases, tools and techniques in one place. in Offence, Defence & OSINT →

An open source OWASP tool for drawing data flow diagrams and doing threat modelling with methods such as STRIDE, with web and desktop versions. in Offence, Defence & OSINT →

Payloads and bypass notes for web security and CTFs, organised by vulnerability class (SQLi, SSRF, XXE, SSTI and more). in Offence, Defence & OSINT →

An e-zine of the hacker community, published since 1985, with deep technical articles on exploitation, kernels and network security. in Offence, Defence & OSINT →

A hand-curated guide to links and resources split by topic for SOC, pentesting, DFIR, threat intelligence and AppSec. in Offence, Defence & OSINT →

A search engine for internet-facing devices, servers and services, indexed by their service banners. in Offence, Defence & OSINT →

A scanning service that opens a URL in a real browser and records every request the page makes, the domains it contacts, a screenshot and the DOM. in Offence, Defence & OSINT →

A single page listing web application security tests as a mind map; each branch is a test area with its tools. in Offence, Defence & OSINT →

Map and search interface for volunteer-collected worldwide Wi-Fi, Bluetooth and cell-tower observations. in Offence, Defence & OSINT →

A user-submitted archive of reverse engineering challenges (crackmes), filterable by difficulty, language and platform. in CTF & Hands-on Labs →

A set of 48 programming exercises in 8 sets that teach cryptography by attacking real constructions; you write the attacks yourself. in CTF & Hands-on Labs →

A long-running site with basic hacking missions (basic, realistic, programming, stego) in a legal, safe setting. in CTF & Hands-on Labs →

HackerOne's free video lessons and CTF on finding web vulnerabilities; flags earned can bring invitations to private bug bounty programs. in CTF & Hands-on Labs →

A developer-oriented site that explains common web vulnerabilities (XSS, SQL injection, CSRF) in short interactive lessons. in CTF & Hands-on Labs →

An embedded-systems CTF where you break electronic locks using an in-browser MSP430 debugger. in CTF & Hands-on Labs →

OWASP's web application penetration testing methodology and checklist, from information gathering to business logic flaws. in CTF & Hands-on Labs →

Web and application security exercises where each one explains a vulnerability and gives you a running environment to exploit it. in CTF & Hands-on Labs →

Carnegie Mellon's free CTF platform with web, crypto, reverse engineering and forensics tasks. in CTF & Hands-on Labs →

Arizona State University's free cybersecurity education platform; beginner-friendly modules with in-browser practice… in CTF & Hands-on Labs →

A non-profit wargame site for binary exploitation (pwn), starting at the Toddler's Bottle tier and getting harder. in CTF & Hands-on Labs →

Harder binary exploitation tasks aimed at building pwn skills on near-real vulnerabilities. in CTF & Hands-on Labs →

A community-run French platform with hundreds of challenges and virtual environments across web, cryptography, reverse engineering and forensics. in CTF & Hands-on Labs →

Docker-compose environments for known CVEs that come up with one command. in CTF & Hands-on Labs →

An archive of community-built vulnerable VMs you download and run locally. in CTF & Hands-on Labs →

The Application Security Verification Standard: measurable security requirements in areas such as authentication… in Certification & Career →

A self-study curriculum that orders free resources by topic for people teaching themselves information security. in Certification & Career →

Visualisation of global wind, ocean-current and air-pollution forecasts on a live globe. in Science & Academia →

An open catalogue of scholarly works, authors, institutions and journals; all the data is CC0 and queryable through a free API. in Science & Academia →

The twice-yearly ranking of the 500 fastest supercomputers by LINPACK results, with all past lists. in Science & Academia →

Turkey’s government scholarship programme for international students at bachelor’s, master’s and doctoral level… in Science & Academia →

Placement data for Turkish undergraduate and associate programmes: base scores and ranks, quotas, which provinces and… in Science & Academia →

Statistics from the Council of Higher Education’s information system: student and academic-staff counts by university, faculty and programme. in Science & Academia →

An open-source reference manager: its browser connector saves the citation and PDF from an article page in one click… in Science & Academia →

The Public Procurement Authority’s platform; tender and award notices are publicly searchable. in Economics →

The Turkish central bank’s time-series store: exchange rates, interest rates, money supply, balance of payments and the market participants survey. in Economics →

Turkish Statistical Institute’s official statistics portal: inflation (CPI, PPI), GDP, labour, population and… in Economics →

The platform where Borsa Istanbul companies publish their legal disclosures: financial statements, material-event… in Finance, Markets & Crypto →

Takasbank’s investment-fund platform; its public pages compare prices, period returns and asset allocation across funds. in Finance, Markets & Crypto →

Enter a foreground and a background colour and it gives the contrast ratio and whether it passes WCAG AA/AAA for normal… in UI Design, Colour & Type →

The Turkish ICT Authority’s free online learning platform: programming, cyber security, AI and networking courses, with a certificate on completion. in Learning & Roadmaps →

A career platform for developers in Turkey: company-sponsored bootcamps and hackathons, plus public interview… in Learning & Roadmaps →

A colourful comic that shows how a DNS query is resolved through resolvers, root and TLD servers. in Learning & Roadmaps →

A one-page comic that explains HTTPS, certificates and key exchange. in Learning & Roadmaps →

A short book by curl's author Daniel Stenberg explaining the HTTP/2 protocol, including headers, streams and server push. in Learning & Roadmaps →

A step-by-step tutorial that builds a SQLite-like database from scratch in C: REPL, B-tree, pager, cursors. in Learning & Roadmaps →

A community guide to server setup, networking, security and service configuration on the Rocky/RHEL family, step by step. in Learning & Roadmaps →

Course slides built from Markdown for React, Vue, Python, data science, HTML/CSS, JavaScript/TypeScript and databases, with exercises and solutions. in Learning & Roadmaps →

A browser visualisation that animates how SHA-256 turns an input into a hash, showing the bits in memory and each round. in Learning & Roadmaps →

A Turkish career platform with company-sponsored bootcamps, job listings and public resources (technical glossary… in Learning & Roadmaps →

A page that walks through every byte of a TLS 1.2 handshake with colour-coded, annotated and hand-computed values. in Learning & Roadmaps →

Lays out the skills to learn as a web developer (HTML, CSS, JS, tooling, testing, performance) as a visual map, with… in Learning & Roadmaps →

A detailed step-by-step account of everything that happens when you type an address in a browser and press Enter (DNS, TCP, TLS, HTTP, rendering). in Learning & Roadmaps →

The body that runs Turkey’s central exams (YKS, KPSS, ALES, YDS); its public pages carry the exam calendar, guides… in Learning & Roadmaps →

An English translation and extension of the e-maxx.ru write-ups on competitive-programming algorithms, each topic with code and practice problems. in Practice & Challenges →

A scenario-based game for learning SELinux that you run on your own machine. in Practice & Challenges →

Gwern Branwen's personal archive and digital garden of very long, heavily sourced essays on AI, psychology, statistics and internet history. in Free Books & Long Reads →

A long-standing site with detailed tutorials on Unix tools such as sed, awk, csh and regular expressions. in Cheat Sheets & Quick Reference →

A dense single-page summary of Python syntax, collections, the standard library and common modules. in Cheat Sheets & Quick Reference →

The central archive of TeX and LaTeX packages: each package’s documentation, version, licence and maintenance status on one page. in Cheat Sheets & Quick Reference →

Draw the symbol you want with the mouse and it returns the matching LaTeX command and the package it needs. in Cheat Sheets & Quick Reference →

A long single-page AWK tutorial taught from scratch with examples. in Cheat Sheets & Quick Reference →

A tutorial on grep, egrep and fgrep and regular expression syntax, with examples. in Cheat Sheets & Quick Reference →

A single-page sed tutorial built around addresses, commands and regular expressions. in Cheat Sheets & Quick Reference →

A catalogue of commonly needed regular expressions (email, phone, dates, IP addresses), each with a diagram, an explanation and a place to try it. in Cheat Sheets & Quick Reference →

Julia Evans' page of drawings and zines that explain Linux, networking, debugging tools and systems concepts. in Cheat Sheets & Quick Reference →

A browsable, searchable tree of object identifiers (OIDs), handy when decoding X.509 certificate fields. in Cheat Sheets & Quick Reference →

Short, implementation-focused guides on application security topics such as authentication, injection prevention and session management. in Cheat Sheets & Quick Reference →

A filterable list of XSS vectors by tag, event handler and browser. in Cheat Sheets & Quick Reference →

A recipe collection for doing string, array, file and loop work in pure POSIX sh without calling external commands like sed, awk or cut. in Cheat Sheets & Quick Reference →

The Turkish Language Association’s dictionaries behind one search box: the current Turkish dictionary, the spelling… in Cheat Sheets & Quick Reference →

A compact collection of command-line tips split into everyday, advanced and situational sections, translated into dozens of languages. in Cheat Sheets & Quick Reference →

A widely used single-repo compilation of manuals, cheat sheets, one-liners and CLI/web tools for sysadmins, DevOps and security work. in Cheat Sheets & Quick Reference →

A Turkish–English online dictionary that groups translations by field (computing, law, medicine and so on) and gives pronunciations. in Cheat Sheets & Quick Reference →

A classic one-page reference to Unix/Linux administration commands: networking, filesystems, processes, SSH, security. in Cheat Sheets & Quick Reference →

A collaborative LaTeX editor in the browser; compilation runs on the server and thousands of journal and thesis templates are ready. in Editors, IDEs & Terminals →

A new typesetting language meant as an alternative to LaTeX, and its online editor; the compiler is open source (Rust)… in Editors, IDEs & Terminals →

GCHQ's in-browser data transformation tool: base64, hex, crypto, compression and parsing chained as a drag-and-drop 'recipe'. in Converters, Formatters & Checkers →

A browser tool for drawing points, lines and polygons on a map while editing the GeoJSON in a side panel; it exports to… in Converters, Formatters & Checkers →

A browser tool that simplifies map data in shapefile, GeoJSON, TopoJSON or CSV and converts between those formats; the… in Converters, Formatters & Checkers →

Turns a JavaScript regular expression into a railroad diagram, with groups, alternatives and repetition drawn as boxes and arrows. in Converters, Formatters & Checkers →

A form that generates the CAA DNS record, which controls which certificate authorities may issue certificates for your… in Converters, Formatters & Checkers →

You build a table cell by cell in a visual grid and it emits LaTeX, HTML, Markdown, plain text or MediaWiki, and accepts pasted CSV. in Converters, Formatters & Checkers →

A searchable catalogue of roughly 40,000 open-source projects with summaries, categories and quality scores, also exposed to coding agents via MCP. in Lists, Directories & Discovery →

A list of real-time map and data-visualisation sites (aviation, space, weather, history, marine, cyber threats). in Lists, Directories & Discovery →

Topic-grouped list of ready-made notes vaults and digital gardens for developers and learners, downloadable for offline… in Lists, Directories & Discovery →

A web-scraping list of libraries, services and manuals split by language (Python, PHP, Ruby, JS, Go, CLI). in Lists, Directories & Discovery →

A list of Zsh plugins, themes and the frameworks that manage them (Oh My Zsh, antigen, zinit and others). in Lists, Directories & Discovery →

A weekly-updated, star-ranked list of about 100 digital gardens (personal wikis and note sites) whose source lives in a git repository. in Lists, Directories & Discovery →

A list of headless browsers and their drivers (Puppeteer, Playwright, Selenium, PhantomJS successors and more) sorted by language. in Lists, Directories & Discovery →

Combines hackerspaces, fablabs and makerspaces from SpaceAPI, Fablab.io and the Hackerspaces wiki on one map, with a heatmap of open/closed status. in Lists, Directories & Discovery →

The digital preservation community's shared portal for file formats, tools and resources, with format data compiled… in Open Access & Archives →

Turkish laws, decrees and regulations in consolidated form, with later amendments worked into the text. in Open Access & Archives →

Turkey’s official gazette: each day’s issue and an archive of past ones; legislation takes effect as published here. in Open Access & Archives →