Frequently Asked Questions

SadServers is a hands-on Linux and DevOps practice and assessment platform. You troubleshoot realistic problems on real virtual machines (web servers, databases, Docker, Kubernetes, and more) through a browser-based terminal, with automated checks to verify your fix.

We believe the best way to learn is by doing. Reading docs and watching tutorials helps, but passive study only goes so far. SadServers puts you on real Linux VMs with realistic problems: misconfigured services, broken deployments, and production-style outages you diagnose and fix yourself. The same hands-on approach is how we think skills should be assessed, whether you are training for yourself or evaluating candidates in an interview. You build muscle memory by troubleshooting under time pressure, not by memorizing answers to multiple-choice questions. See our About page for more.

Individual engineers and students building practical skills; hiring teams and organizations running technical interviews or training; and anyone preparing for DevOps, SRE, or Linux sysadmin roles who wants experience beyond tutorials and multiple-choice questions.

Choose a scenario, start a session, and SadServers provisions a VM with a pre-configured problem. Use the in-browser terminal (or SSH on eligible plans) to diagnose and fix it, request clues if you are stuck, then submit your solution for automatic validation. Your progress is saved to your account dashboard.

See the SadServers project on GitHub: github.com/SadServers/sadservers.

No. For the web experience, scenarios run in your browser. Pro+ and Business subscribers can optionally use direct SSH or the CLI/TUI client instead; both are optional, not required.

Scenarios range from beginner-friendly to advanced. Basic command-line comfort helps on early scenarios; harder challenges assume familiarity with systemd, networking, common daemons, containers, or orchestration depending on the topic. Browse scenarios by difficulty and topic to find a starting point.

Yes. The Hobbyist (free) plan includes a selection of scenarios with daily limits, enough to see how SadServers works. When you are ready for the full catalog, unlimited practice, and advanced features, see Pro, Pro+ & Business Accounts or compare plans on the pricing page.

Sign up with email and password, or use Google sign-in at the SignUp page.

By creating an account, you can save your progress (which scenarios you have solved and in what time), and access your saved servers.

Google sign-in is supported on the login page. GitHub is not used for account login today.

Use the password reset page to receive a reset link by email. If you signed up with Google only, sign in with Google instead; you do not need a SadServers password.

Scenarios are interactive exercises or challenges (also called "labs" or "sandboxes"). Each one drops you into a Linux VM with command line access.

Scenarios run on virtual machines (VMs) provisioned as AWS EC2 instances. There are two types of VMs.

Regular VMs (non-paying users) run inside a private subnet; no network traffic is allowed in or out except through a proxy server that serves the in-browser command line interface.

Paying accounts get VMs with a public IP, offering direct SSH connection and outbound access to the Internet. See direct SSH access under paid plans.

Every scenario has a Type shown on its detail page and in scenario lists, depending on the type of activity:

Fix: troubleshoot an issue. Something is broken or misconfigured; diagnose and repair it.
Do: install or configure something that is not broken yet. Build or set up a service, stack, or workflow from a starting point.
Hack: security scenarios. Break into a system, own it or escalate privileges (offensive skills in a controlled lab environment).

Scenarios have different types of access:

Free, without registration: anyone can run.
Free, with registration: anyone with a registered account can run.
Paid “Pro” scenarios: require a paid account (Pro, Pro+, or Business). These scenarios tend to be the best ones, the most realistic, and more suitable for preparing or running job interviews.
Business scenarios: available only to Business accounts.
Private scenarios: unpublished scenarios custom-made for a specific Business account. Only members of the business organization or candidates invited by them can access this type of scenario.

Labs are free reference pages (introductory guides, cheatsheets, and troubleshooting notes) for technologies covered in scenarios (e.g. web servers, Docker, Kubernetes, databases, and more). They complement hands-on practice but are not scored exercises.

The web button calls an agent in the VM which runs the ~/agent/check.sh script. This script returns “NO” or “OK” and the web page shows the result as incorrect or correct accordingly.

The result is also logged in ~/agent/sadagent.txt. So if you want to troubleshoot this disparity, you can 1) look at the result of this log, 2) run the check.sh script directly, and 3) inspect the script to see how it works.

In almost all scenarios you can also look at the Clues (which include one possible solution).

Note that changing the existing check.sh script in any way will make the solution fail automatically.

It is possible that your solution is right but the check.sh script doesn't capture it properly; the script can have both false positives and false negatives.

If you open several scenarios (several servers are running at the same time, not recommended), the “Check My Solution” button should go to the latest session (latest VM normally) created, regardless of what scenario page you are in, which can be confusing.

This is the time for an AWS EC2 instance to be provisioned and ready to run its services. We have found this time to be bimodal: most instances take about 50 seconds and some take about 10 seconds only. We attribute this to internal AWS workings.

Each scenario has a difficulty level (easy, medium, hard). Easy scenarios focus on fundamentals; hard ones mirror senior-level interview or on-call complexity. Browse by topic at the Scenarios page or use topic filters on scenario list pages.

Most scenarios list an estimated time budget. Pro and Pro+ subscribers receive double the base time limit per scenario. VMs also have a maximum session lifetime; finish or save progress before the VM is reclaimed.

Some scenarios are deliberately tight on time, and many users find certain challenges feel rushed at first. That is partly by design:

Urgency. Real troubleshooting happens under pressure: production incidents, on-call pages, and technical interviews. A time limit trains you for that pace better than an open-ended lab.
Cost. Every session runs on a real cloud VM in AWS. SadServers has provisioned close to a million servers; even with a generous free tier, long-running VMs carry real infrastructure cost.
You can retry. If your VM expires before you finish, start the scenario again (free-tier daily limits may apply; paid plans allow unlimited practice).
Difficulty. Time budget helps classify how demanding a scenario is. One that sits between medium and hard might get a shorter limit so it reads clearly as hard.
We tune limits over time. We review durations from user feedback and from solve metrics (how often people finish, average time to solve) and adjust when a limit feels unfair or mislabeled.

Yes. You can start a new session for the same scenario. Free-tier limits may restrict how often you can retry in a given time period; paid plans allow unlimited practice on all scenarios.

Yes. During a session you can reveal clues progressively. Using clues does not block you from solving the scenario, but clue usage appears in organization dashboards when assessing candidates or team members.

The clues accessible during the session include a solution. Do not publish or share solutions to paid scenarios (Pro, Pro+, or Business scenarios); see Content & IP. Business-exclusive interview scenarios are also kept unpublished so candidates cannot memorize answers beforehand.

Not necessarily. The solution given in the clues is one possible solution. It may be "the" solution in a particular scenario, but often there are multiple ways to solve a scenario.

Besides, the solution given in the clues is meant to solve the particular immediate issue in the scenario in isolation, and may not be a good practice in general. For example, deleting a big log file in a VM with a full disk in order to restore the service can be given as a solution, but in an environment outside a single VM, a sysadmin could use safer approaches like transferring the log file to a different machine first or increasing the disk size.

Individual users cannot author public scenarios yet through the UI. Business customers can request custom private scenarios tailored to their needs; contact info@sadservers.com.

We add new scenarios regularly across existing and emerging topics. Watch the new scenarios list and follow our social media accounts or subscribe to our newsletter for announcements.

Yes. It is not common, but some scenarios have been retired due to negative feedback, a confusing goal statement, or not being very valuable overall. If you think a scenario does not meet a minimum quality bar, please let us know.

Yes. The public SadServers GitHub repository includes scenario descriptions and tests: github.com/SadServers/sadservers/tree/main/scenarios.

Organizations and companies are evaluating AI agents, and we want to avoid AI models already having the solution.

Scenarios run on real cloud VMs, most commonly Debian. The stack matches the exercise: web servers, databases, containers, Kubernetes, and so on. When using direct SSH, log in as admin.

It depends on the scenario. Each scenario page shows Root (sudo) Access: Yes/No. Most scenarios grant sudo so you can fix system services and configs. Some scenarios restrict sudo on purpose, and part of the challenge may be working within limited privileges, like being able to restart a service (you can usually still run sudo shutdown to end the VM early).

Each scenario uses a purpose-built image, not a blank server. Services, packages, and misconfigurations are set up to match the problem statement. Read the scenario description, test instructions, and tags to see what stack you are working with. On Pro+ and Business plans, VMs have a public IP address and outbound internet access so you can install additional tooling when a scenario allows it.

Yes, for now each scenario session gives you one cloud VM to connect to (browser terminal or SSH). Simpler scenarios run everything directly on that host. More complex exercises simulate multiple servers or tiers using Docker and Kubernetes on the same VM, so you might troubleshoot a multi-container app or a small cluster without juggling separate SSH sessions to different machines. The scenario description and tags indicate when containers or K8s are part of the setup.

No, for regular ephemeral scenarios. Each run starts a fresh VM; if you break something badly, don't worry, you can just start a new session. Resumable scenarios are different: your disk state is kept when you stop and start the same VM (see below). If you interfere with SadServers infrastructure on ports 2020 and 6767, then the console-to-web service or the "Check My Solution" button may stop working.

Browser (default): All plans can use the in-browser terminal; no install required. You need a recent desktop browser (Chrome, Firefox, Safari, or Edge), with JavaScript enabled. See Technical Issues if the terminal will not connect.

Your own SSH client: Pro+ and Business subscribers can upload an SSH public key on the dashboard, download a one-time key from the running scenario page, or use sads ssh via the CLI/TUI. A physical keyboard and desktop/laptop are strongly recommended; tablets are a poor fit for terminal work.

Most VMs are isolated from the public internet by default; local DNS is available, but outbound access is blocked unless the scenario requires it. Paid (Pro, Pro+ and Business) plans enable internet access on VMs, which some scenarios need. The scenario description will indicate when external access matters.

Most SadServers scenarios spin up an ephemeral VM (a new instance each time), destroyed when you finish or time out. A smaller set uses resumable VMs instead: you can stop and resume the same server and keep your work.

While connected, click Stop & Resume Later on the scenario page (shown only for resumable scenarios). Manage the server from Your Saved Server on your dashboard: Stop, Start, or Destroy. You can have only one resumable server at a time. Files, packages, and configs persist across stop/start until you destroy the VM or it is automatically removed after about seven days.

Resumable servers are ideal for longer, self-paced work, for example following the Linux Upskill Challenge on a single Linux box over several sessions. Standard troubleshooting scenarios remain ephemeral by design.

Your dashboard shows solved and unsolved scenarios, best solve times, attempt counts, and running sessions. The public scenarios list also marks scenarios you have completed.

A scenario counts as completed when you click Check My Solution and the automated checker confirms your fix. SadServers records the solve time (seconds from VM start to successful check), clues used, and attempt count on your account. Unfinished sessions (VM expired or abandoned without a passing check) do not count as solved. You must be logged in for progress to persist; anonymous practice does not save to a long-term profile.

You earn trophy points the first time you solve each scenario: 1 point for easy, 2 for medium, and 5 for hard. Re-solving a scenario you already completed does not add more points, but your dashboard keeps your best time if you beat a previous attempt. If you solve without using clues, you may see a message when your time is the fastest recorded for that scenario. Points accumulate into expertise tiers on your dashboard: Beginner, Intermediate, Advanced, and Master.

The Ranking page at /ranking shows the top 20 users by total trophy points. It is a Pro Account feature; Pro subscribers can compete for a spot by setting an alias on their dashboard (see Certificates & Badges). Points are awarded when you solve a scenario for the first time: Easy = 1 point, Medium = 2 points, Hard = 5 points. Re-solving the same scenario does not add more points. Your dashboard tracks the same point total used for ranking.

SadServers does not track daily or weekly practice streaks. Progress is measured by scenarios solved, best times, trophy points, and ranking, not consecutive days of activity.

Yes. Progress is tied to your SadServers account, not to a specific browser or machine. Sign in on any device (laptop, desktop, or another network) and your dashboard, solved scenarios, points, and session history follow you. The in-browser terminal and optional SSH client are just different ways to reach the same cloud VM; your account record is updated the same way when you pass the solution check.

Yes on paid plans (unlimited practice). The free tier limits retries on scenarios you have already solved; see plan details on the pricing page.

On SadServers, start with Linux & Bash scenarios, then move through web servers, databases, Docker, and Kubernetes as you grow. The individual solutions page outlines a suggested mastery path; troubleshooting guides and Labs offer reference material. For structured learning outside the platform, see learning Linux and DevOps projects below.

A popular free starting point is the Linux Upskill Challenge community on Reddit (r/linuxupskillchallenge), a practical, hands-on path from basics to competent command-line use. SadServers offers resumable Linux VMs you can stop and pick up later, which work well for multi-day Upskill Challenge exercises. Combine that with Linux & Bash scenarios for troubleshooting practice on real broken-server exercises.

The DevOps Upskill Challenge (DOUC) is a free curriculum from “Hello World” through Kubernetes: objective-based, hands-on challenges across Linux, HTTP, Git, cloud, Docker, Terraform, CI/CD, observability, and more. Working through it builds a Git-based DevOps project you can show on a résumé. SadServers complements DOUC with on-demand troubleshooting scenarios when you want to stress-test ops skills in broken production-style environments.

Scenarios are tagged by difficulty within each technology topic. Combine topic filters (e.g. Docker, Kubernetes) with difficulty levels to build your own track rather than a single fixed curriculum.

Certificates are a shareable record of your troubleshooting progress: a public Achievements page and a downloadable PDF showing your competency level and trophy points earned on SadServers. Badges are embeddable images (Markdown, HTML) you can add to a GitHub profile README, portfolio, or résumé; the badge reflects your current level and can link to your public certificate page.

All registered accounts (including free ones) can earn trophy points and make use of embeddable badges. Only paid plans (Pro, Pro+, Business) can set up a Certificate of Achievement page, a downloadable PDF, and a shareable URL. Both badges and certificates are available from the Achievements section of your dashboard.

Levels are based on trophy points from first-time scenario solves: 1 point (easy), 2 (medium), 5 (hard). As points accumulate you progress through Beginner, Intermediate, Advanced, and Master. Your badge and certificate update automatically as you solve more scenarios. See Learning, Progress & Scoring for full scoring rules.

Open your dashboard → Achievements, click Edit Certificate Details, and enter a name or alias. Choose whether to make the page public. When published, your certificate lives at a URL like /u/your-alias/. You can unpublish or edit details anytime from the same dashboard section.

After setting your name or alias on the Achievements page, use the Download as PDF button on your certificate preview (/u/your-alias/ when logged in as the owner). The PDF matches your current level and point total; download again after solving more scenarios to refresh it.

In the dashboard Achievements section, pick a badge style (For The Badge, Flat Square, or Plastic), copy the Markdown or HTML snippet, and paste it into your GitHub profile README or site. If your certificate page is public, the badge links to your personal Achievements URL; otherwise it links to SadServers.com. You can also copy the badge image URL directly.

Yes, if you publish your Achievements page. Anyone with the link can view your level, points, and solved-scenario summary online; the PDF reflects the same data. It is a verifiable record of hands-on practice on SadServers, not a formal industry accreditation or exam proctored by a third party. You can add a link to your certificate page to your résumé or LinkedIn profile.

It shows you worked through a Linux or DevOps challenge under time pressure, with an automated check confirming the fix, not just multiple-choice knowledge. Your certificate and badge summarize how many scenarios you have solved and at what difficulty mix; employers use them as evidence of practical troubleshooting experience.

The free tier is great for trying out SadServers, but it caps how many scenarios you can run per day and which challenges are unlocked. A paid plan removes those limits so you can practice like you would on the job: retry scenarios until they stick, work through harder topics, build trophy points toward a public certificate and badge, and compete on the ranking. Most learners who are preparing for interviews or leveling up sysadmin skills move to Pro once they have outgrown the daily free limits.

Hobbyist (free): a limited scenario selection with daily rate limits.
Pro: all scenarios, unlimited practice, double session time, achievements page, ranking, and email support.
Pro+: everything in Pro plus direct SSH, VMs with internet access, command history, scenario invitation links, and the CLI/TUI client.
Business: organizations for hiring and training: unlimited internal users, interviews, candidate assessment, business-exclusive scenarios, API access, and Pro+ features for members.
Compare pricing on /pricing and business pricing.

Choose Pro if you are an individual learning Linux or DevOps and want every scenario, unlimited retries, double session time, achievements, ranking, and email support; this is the default upgrade from free.

Choose Pro+ if you already practice regularly and want a more realistic workflow: your own SSH client, internet access on VMs, a 30-day command history log, scenario invitation links to share with others, and the CLI/TUI. See direct SSH, command history, and scenario invitations below.

Choose Business if you represent a company (hiring, training, or events). You get an organization workspace, Job Interviews, candidate dashboards, business-exclusive scenarios, API access, and Pro+ features for members. Business accounts have unlimited users (internal or external). Companies must use Business rather than stacking individual Pro accounts. See solutions for business.

The Business pay-per-use account is a Business account with all the same benefits. Instead of purchasing a monthly or yearly subscription, you make a one-time purchase of a package that includes a fixed number of interview sessions (for example, 25 or 50), which you can use at any time.

An interview session (also referred to as an “interview” or “session”) represents a single scenario run, regardless of how it is initiated.

You can top up your pay-per-use account at any time.

Pro+ and Business subscribers can connect to scenario VMs with their own SSH client instead of the in-browser terminal only. Upload an SSH public key on your dashboard (account settings), or download a one-time private key from the running scenario page when offered. Then use a standard ssh session (same VM, your preferred terminal emulator, copy/paste, and local tooling). Not every scenario exposes SSH on purpose (some breaks are part of the challenge). See also Scenario Environment and the CLI/TUI (sads ssh).

Pro+ and Business accounts can record the shell commands you type during scenarios. For your own sessions, open Your Logged Scenarios on the dashboard to view or download bash history from the last 30 days, useful for reviewing what you tried after a tough solve. On some complex scenarios, logging may start up to ~15 seconds after the shell prompt appears, so the very first commands might be missing. Business organizations can also review candidate command history for interview scenarios. See the Pro+ guide.

Pro+ subscribers can create one-time invitation URLs from the dashboard (Invitations section) for any scenario (including Pro-only challenges) and share the link with anyone. The recipient opens the URL and the scenario starts without needing a SadServers account or signup. Handy for sharing an exercise with a friend, mentee, or informal try-out. Pro+ accounts include a limited number of invitation credits (see your dashboard). This is separate from Business interview invites, which are tied to organizations, candidates, and structured hiring workflows; see Job Interviews.

Business is built for hiring teams, training programs, and companies running technical assessments at scale. You get an organization workspace, structured interview flows with candidate dashboards, review of candidate command history, business-exclusive scenarios, unlimited internal members with Pro+ features, domain-based access, and API integration. If more than one employee needs SadServers for work, or you run live or take-home interviews, Business is the right tier, not a collection of individual Pro subscriptions. Explore solutions for business and business pricing (subscription or pay-per-interview bundles).

Yes. If you have an active Pro+ subscription, you can start a 7-day free Business trial from the pricing page; look for the “Try Business” button on the Business plan. You get a trial organization with interviews, candidate management, and other Business features (business-exclusive scenarios are not included during the trial). When the trial ends, you return to your Pro+ plan unless you purchase a Business subscription; organization data from the trial is kept if you upgrade. Each account gets one trial; Free and Pro users must upgrade to Pro+ first.

Sign in (or create an account), open the pricing page, and choose Pro or Pro+ (monthly or yearly). Checkout runs through Stripe; your plan activates immediately. Already subscribed? Use Manage billing on your dashboard to upgrade Pro → Pro+, switch billing interval, or update payment details. For Business, use the business pricing page or contact us for larger deployments. Billing mechanics (cancellation, refunds, invoices) are covered under Subscription & Billing.

Yes. You can buy a one-time Pro+ gift for anyone at the gifts page (no SadServers account required to purchase). Recipients redeem via a link in the gift email; the plan duration starts when they redeem. Gifts do not expire and are transferable but non-refundable. Ideal for professional development budgets, holidays, or team gifts.

Yes. Many employers and training programs cover SadServers through a one-time gift purchase: your organization (or manager) buys Pro+ access at the gifts page and sends the gift to your email. No company SadServers account is required to buy; you redeem the gift on your own account when ready. This works well for professional development or training stipends. For ongoing team access, interviews, or org-wide billing, see Business plans instead.

Business accounts create interviews in the organization dashboard, assign scenarios, and invite candidates. Each candidate receives a link, runs scenarios in isolated VMs, and results (time, clues, pass/fail) appear in your dashboard. See solutions for business.

SadServers supports two main styles:

Live interviews. The candidate works through a scenario while the interviewer is on the call (video or screen share). You see how they think, communicate, and troubleshoot in real time. Live sessions suit later interview stages when you want richer signal about a candidate's skills.
Asynchronous interviews. You send the candidate an invitation link; they run the scenario on their own time within the window you set. Results (pass/fail, time, clues used) land in your dashboard when they finish. Async interviews work well as a filter step when you have many applicants and need scalable screening before investing in live loops. In async interviews, the interview creator is notified by email when the candidate starts a scenario.

Candidates don't need to create a SadServers account; with the shared "magic" link to a scenario, the candidate can run the scenario directly.

From your organization dashboard, add candidates to an interview and send invitation links. Candidates accept the invite and run the assigned scenarios.

No, candidates do not need a SadServers account to run the scenarios.

Yes. The organization dashboard shows activity, completions, time-to-solve, and clues used for members and interview candidates as they work through scenarios.

Scenarios use automated solution checks, the same engine individual learners use. You see whether the candidate solved each task, how long it took, and how many clues they requested. Subjective review of their command history is not required for basic pass/fail screening. We do recommend in live interviews not to rely exclusively on the automated checks (i.e., if the candidate solved the scenario), but rather to look at overall criteria like communication skills, problem-solving approach, and technical depth.

Yes. Choose from the business scenario catalog (including business-exclusive challenges) or request custom private scenarios built for your interview loop.

Yes. When you create the interview, you can set the maximum time the candidate has to complete each scenario.

Yes. When creating the interview, if you select a scenario time longer than two hours, the scenario timer is not shown.

Yes. When creating an interview, you have the option to show or hide the clues (hints) in the interview scenarios.

One or two medium scenarios often fit a 45–60 minute live loop; harder scenarios may need longer. Pay-per-use and subscription options let you scale session volume for high-volume hiring seasons; see business pricing.

Sessions are tied to running VMs with time limits. If a VM expires and you want the candidate to retry, you have to create a new invitation link for them and they have to start a new attempt with the new scenario link. You can customize the time the candidate has for each one of the scenarios in your interview.

An organization is a Business workspace for hiring and training. It includes a shared dashboard, interviews, candidate management, business-only scenarios, API access, and optional domain-based access for your company email. Organizations must use Business rather than individual Pro accounts.

Organization owners invite colleagues from the dashboard. Members join via invitation link or by matching your verified company domain if domain access is enabled.

Contact info@sadservers.com if you need to transfer organization ownership or reassign billing contact.

Business accounts (both subscriptions and pay-per-use packages) have no seat limitations; they can use an unlimited number of internal members or external users (candidates).

Business members get access to business-tier content, including exclusive Business scenarios not available on individual plans and custom Private scenarios if they have them. Interview assignments limit which scenarios a candidate sees.

Yes. Business subscriptions and pay-per-use packages cover most teams; larger deployments with custom SLAs, volume pricing, or special compliance needs should contact info@sadservers.com.

Single sign-on is not offered today. Enterprise customers should contact us to discuss SAML/OIDC requirements and roadmap timing.

Yes. We build private scenarios matching your infrastructure, tooling, and interview bar. They are visible only to your organization.

SadServers is primarily offered as a hosted SaaS platform. Contact sales if you have a hard requirement for private cloud or on-premises deployment.

Yes, and not just in theory. Several organizations and companies already use SadServers to benchmark AI models and autonomous agents against realistic Linux and DevOps troubleshooting tasks. That includes general-purpose coding agents and specialized SRE or ops agents. Each scenario runs on a real VM with an objective pass/fail check, so you get reproducible results rather than subjective grading. Teams typically use the API or CLI/TUI to spin up scenarios programmatically and record solve times and outcomes. Contact info@sadservers.com if you need a Business account, custom scenarios, or help designing an evaluation workflow.

We support classrooms and training programs on a case-by-case basis. Email info@sadservers.com with institution details, expected headcount, and term dates.

Application data is hosted on cloud infrastructure (including AWS for scenario VMs). Payment data is stored by Stripe. Contact us for a current data-processing summary if your procurement team requires it.

All payments (subscriptions and one-time purchases) are processed securely through Stripe. Your credit card details are never seen or stored by us.

You are charged at the start of each billing period (monthly or yearly depending on the plan you chose) until you cancel.

You can cancel at any time; this means the subscription won’t be renewed and you won’t be charged again for it. Cancel from the Stripe billing portal linked on your dashboard.

You keep paid access until the end of the current billing period, then your account reverts to free-tier limits. Your solve history remains on your dashboard.

Not currently. We plan to implement subscription pausing in the future.

Yes. Upgrade or change billing interval through the Stripe customer portal (Manage billing on your dashboard). Moving between Pro and Pro+ or monthly and yearly is handled there with proration per Stripe rules.

Generally no. Annual Pro or Pro+ subscriptions cancelled after two months may qualify for a pro-rated refund on the remaining term; contact info@sadservers.com. See Terms and Conditions.

Open your SadServers dashboard, click Manage billing to open the Stripe customer portal, then go to the Invoice history section to view and download your latest invoices and receipts. We also send an invoice and receipt by email each time a charge is processed.

Major credit and debit cards through Stripe. Business checkout may support additional billing options; contact sales for purchase orders or invoicing arrangements.

Common causes: expired card, insufficient funds, or bank fraud blocks. Update your payment method in the Stripe portal. Stripe will retry failed subscription payments automatically; you receive email notices from Stripe when action is needed.

As far as we know, most browsers are supported. JavaScript is needed.

SadServers generally works on tablets and even phones, but the terminal experience is designed for desktop keyboards. We recommend a laptop or desktop for serious practice.

Wait until the VM status shows running; provisioning can take a minute. If it persists, try a browser window refresh. You can also try going to your Running servers in the dashboard and launching the terminal from that page. Check whether a corporate proxy blocks our terminal proxy port :8080.

On some OS and browser combinations, Ctrl+W is captured by the browser as “close tab” before it reaches the in-browser terminal (where it would normally delete a word). Try a different browser, or use another binding such as Alt+Backspace to delete a word in the shell. Pro+ and Business users can also use direct SSH or the CLI/TUI with a local terminal emulator.

Each session launches a fresh cloud VM and configures the scenario. Cold starts normally take under a minute; heavy load or AWS capacity in a region can occasionally add delay.

VMs expire after the scenario time limit (see Scenario Environment). Network blips can also drop the terminal UI; refresh and reconnect if the VM is still running; otherwise start a new session from the scenario page.

Pro+ and Business subscribers can use direct SSH; see What is direct SSH access to VMs? in Pro, Pro+ & Business Accounts. You can also use sads ssh via the CLI/TUI when the scenario VM exposes SSH access.

Strict corporate networks that block unknown outbound hosts may prevent the browser terminal from connecting. Allow HTTPS traffic to sadservers.com and our terminal proxy on port :8080 and port :6767 for the "Check My Solution" button functionality, or practice from a less restricted network.

Yes. SadServers provides a REST API to list scenarios, create session VMs, inspect VM status, and shut down instances programmatically. Business accounts can request API access. See the full SadServers API documentation.

The API accepts HTTPS requests with HTTP basic authentication (your SadServers email and password). Only HTTPS is supported. The CLI/TUI uses a separate browser-based device flow (sads auth) and stores a token locally. See the API command-line test section for curl/httpie examples.

Typical workflow: list scenarios (/api/scenarios/), POST a new session to spin up a VM (/api/sessions/), poll for the VM IP (/api/vms/), SSH in, verify the solution, then DELETE the VM when done. Full endpoint specs and field descriptions are in the API docs.

The sads client is a command-line and terminal UI tool for running SadServers scenarios without a browser: browse scenarios, spin up VMs, SSH in, and check solutions from your shell. See the CLI/TUI documentation.

Currently only Pro+ and Business subscribers can run scenarios from the CLI/TUI. The tool is in beta (offered as-is).

Download the binary for your platform (Linux amd64/arm64, Mac amd64/arm64) from the installation table, make it executable, then run sads auth to sign in. Typical flow: sads scenarios → sads up <id> → sads ssh → sads check → sads down. Running sads with no arguments opens the interactive TUI. Mac users may need to allow the unsigned binary under System Settings → Privacy & Security.

LMS integrations, webhooks, and bulk result export are not self-serve today. Business customers can use the API to build custom workflows, or contact info@sadservers.com for integration requirements.

Each session runs on a dedicated VM provisioned for your account. Other users cannot log into your instance (except for Business accounts, where organization members can have live shell access to candidates' VMs).

Account email, usage metadata (sessions, solves, timing), billing records via Stripe, and operational logs for security and abuse prevention. We are not tracking anything from newsletter email messages. We capture web visitor analytics with the self-hosted and privacy-friendly Plausible. There are no third-party cookies set in SadServers (like tracking cookies). When a user logs in using Google OAuth, only their email address is read.

We do not sell or share your personal data.

Yes. Passwords are hashed using Django's standard password hashers. We never store plaintext passwords. Google sign-in users authenticate through Google OAuth.

Solutions to paid scenarios (Pro, Pro+, and Business scenarios) are not to be divulged; do not post them on blogs, YouTube, forums, social media, or course materials. Clues and full solutions are provided inside SadServers for your personal learning.

You may recommend SadServers as a practice platform and link to sadservers.com. You may not copy, redistribute, or build derivative works from SadServers scenarios (including problem statements, VM configurations, clue text, or step-by-step solutions) without written permission from SadServers. For classroom or corporate training use, contact info@sadservers.com to discuss Business accounts or licensing arrangements.

SadServers retains all intellectual property rights in the Service, including scenario designs, VM images, clue text, solution checks, Labs reference pages, and branding. Users receive a limited license to access content through the platform for personal training and assessment, not to reproduce or republish it. See Section 4 of our Terms and Conditions.

Live streams or recordings are fine for personal archives if you do not expose paid-scenario solutions to the public. Do not show clue text, full walkthroughs, or the exact fix for Pro, Pro+, or Business scenarios in published video or write-ups. When in doubt, keep recordings private or blur solution-revealing segments.

Email info@sadservers.com with your intended use (course, book, conference, commercial training, etc.). Custom private scenarios for organizations are available through Business plans; third-party republication or derivative works require explicit written approval.

Email info@sadservers.com with the scenario name, approximate time, browser, and what you expected vs. what happened. Screenshots help.

Contact us at info@sadservers.com. At the time we do not offer security bounties.

Pro+ and Business customers receive email support with typical responses within one business day. Free users are best-effort. Urgent production outages for Business customers should mark the subject line accordingly.