Although this article is titled “Online Tools for System Administrators”, many of the services listed here can be useful to a wider audience. The collection consists mainly of free services, though some offer a paid version with extra features.
KillrCoda
KillrCoda provides a set of interactive environments for the technologies you are learning, teaching or presenting. It is great if you work with Linux, Kubernetes, containers, programming, DevOps or networking. You access it through a web browser and get immediate access to a real, ready-to-use Linux or Kubernetes environment. These environments are hosted remotely and accessed through the browser, so no local resources are used. As a learner you can work through existing scenarios, and as an instructor you can create scenarios for teaching any tool or technology.
Developer Roadmaps
Developer Roadmaps is a community effort to create roadmaps, guides and other educational content to help developers and system administrators choose a direction for their learning.
Let’s Debug
Let’s Debug is an online diagnostic tool that helps you figure out why a Let’s Encrypt™ certificate might be failing to issue. Using a set of tests developed specifically for Let’s Encrypt, it can identify problems such as:
- Incorrect DNS configuration
- Name server issues
- Rate limiting
- Network problems
- CA policy issues
- Incorrect website configuration
Crt.Sh
A database storing the history of all SSL/TLS certificates ever issued for a domain.
Country IP Ranges
This service shows the full ranges of IPv4 and IPv6 addresses organised by country. The lists are in plain text format, which makes them easy to work with. They are updated every few hours, so they are always current.
Internet.NL
Internet.nl analyses the traffic of your service. It shows whether your website, email server or internet connection uses modern and reliable internet standards, and if not, what you can do about it.
Ad Block Test
This tool lets you check how effective your ad-blocking solution is. With a simple interface you can see how many hosts you have blocked. The tool attempts to connect to the most commonly encountered domains across various categories — advertising, analytics, error tracking, social trackers, mixed and OEM.
MyIP.ms
The number one worldwide source for live IP Whois data! Find the hosting company behind any website or the owner of any IP address.
Wigle.Net
Every network ever found! The information on this site is, to put it mildly, unsettling. You can see all WiFi networks that are or ever were available anywhere in the world.
Scamalytics
Scamalytics provides security products for businesses to help them detect and prevent fraud. Enter an IP address to check it and find out the frequency of abuse associated with it.
Composerize
Say goodbye to long Docker run commands and hello to docker-compose up. Just paste your Docker run command into the field and you are done.
Keyboard Keys Generator
If you are into writing in Markdown format, this website can save you a lot of time. It is especially useful when you are writing instructions that frequently reference keyboard shortcuts.
Universal Cyrillic Decoder
This page is useful if you have text that you think was written in Cyrillic but appears as a strange combination of unreadable characters. The tool will try to guess the encoding, and if it cannot, it will show samples with all possible encoding combinations so you can pick the right one.
Internet Archive
Although not aimed specifically at system administrators, this tool can save you when you are looking for documentation on a website that has disappeared, or when a page has been updated with new information that is no longer useful to you.
The Internet Archive is a digital library of web pages and other cultural artefacts in digital form. Like a paper library, its goal is to provide free access to all knowledge.
It has been archiving the internet since 1996. Today it holds decades of web history accessible through the Wayback Machine, and works with 1000+ libraries and other partners through the Archive-It programme to identify important web pages.
The archive currently contains:
- 735 billion web pages
- 41 million books and texts
- 14.7 million audio recordings (including 240,000 live concerts)
- 8.4 million videos (including 2.4 million TV news programmes)
- 4.4 million images
- 890,000 software programmes
Calculator.Net
Calculator.net focuses entirely on providing fast, comprehensive, convenient and free online calculators across many fields. It currently has around 200 calculators to help you quickly work through problems in areas like finance, fitness, health, mathematics and more. New calculators and converters are added regularly. The service is completely free and requires no registration.
That is all for now. If something new and interesting comes along, this article will be updated.