SadServers

What SadServers is

SadServers gives you a real virtual machine that something has gone wrong with, and a web terminal to fix it. Each scenario has a short brief ("a developer created a testing program that is continuously writing to a log file and filling up disk; find it and terminate it"), a time limit, and an automated check that tells you whether you solved it. The site describes itself as "like LeetCode for Linux and DevOps", and that is a fair summary: short, focused problems you solve under a clock.

What the scenarios cover

The library is grouped into Linux and Bash (systemd, networking and DNS, storage, SSH, firewalls, cron), web servers (Nginx, Apache, HAProxy, Caddy, TLS), databases (PostgreSQL, MySQL, Redis, MongoDB, etcd), Docker and Podman, Kubernetes (kubectl, Helm, roles and permissions, Services, Deployments, StatefulSets, Secrets), infrastructure as code (Ansible, Terraform), observability (ELK, Prometheus), tools such as Git, Vault and Jenkins, and a set of security and capture the flag challenges. Scenarios are labelled Easy, Medium or Hard, and by type: Fix, Do, Hack or Playground.

Is it worth your time?

For anyone learning SRE or platform work, yes. Most courses teach you how things work when they are healthy. SadServers only shows you systems that are broken, which is what on-call actually feels like: reading logs, checking which process holds a port, finding the misconfigured unit file. The time limit forces you to build a routine, and many scenarios take 15 minutes or less, so they fit into a lunch break.

Free or paid?

According to the official pricing page in September 2026, the free Hobbyist tier lets you practise on a selection of scenarios with a dashboard to track progress, and you can try it with no sign-up. The Pro plan (USD $9 a month or $72 a year) unlocks unlimited practice across over 125 scenarios with solutions, double the time per scenario and internet access on every VM. Pro+ adds direct SSH access and a command line interface. There are also business plans for teams that use scenarios in hiring and training. Start free and upgrade only if you find yourself running out of scenarios.

Prerequisites and time

Basic Linux comfort helps: moving around the filesystem, reading files, and knowing that ps, ss, df and journalctl exist. The easy scenarios are written so that a beginner can finish them with some searching. Time limits range from 5 to 60 minutes per scenario; working through the free set is a few weeks of occasional practice.

Common questions

Do I need to install anything? No. The server runs in the cloud and you use a terminal in your browser.

Is it only Linux? Linux is the core, but there are Docker, Kubernetes, database and infrastructure as code scenarios too.

What can I do after it? Approach an unfamiliar broken server with a calm, repeatable checklist, and explain what you checked and why when someone asks.

Best for: beginners through experienced engineers who want hands-on troubleshooting practice for SRE, DevOps and platform roles.