Frequently asked questions.

Yes. On the setup screen, look for the box labeled "Skip for now" and click the Skip for now button inside it.

1. You'll be able to read every lesson and practice DSA problems right away.
2. The only thing you'll miss is Zero, your AI coach, until you add one.
3. You can add an AI at any time later - nothing is lost by skipping now.

You can set this up right on the setup screen - no need to skip first.

1. On the setup screen, click "Use my own API key".
2. Pick Claude, ChatGPT (OpenAI), or Gemini from the list.
3. Paste in your API key for that provider, then continue.

Don't have a key yet, or not sure what that means? Click Skip for now instead, and you can set this up later - see the next question.

This specific option isn't on the setup screen - you'll set it up just after, from inside the app.

1. On the setup screen, click Skip for now.
2. Once the app opens, click the gear icon in the top right corner of your app.
3. Find the section called "Zero's model".
4. Click the Custom tab.
5. Enter your server's address and your model name, then save.

No. INDEX 0 opens straight into the app, no sign-up, no login, no email required.

The only time you'd ever create an account is if you choose to turn on Sync, an optional feature for carrying your progress between two computers. Everything else works with zero account, forever.

This happens when the language is installed somewhere the app doesn't automatically check. You can point it there directly.

1. Click the gear icon in the top right corner of your app.
2. Find the section called "Languages".
3. Next to the language that isn't working, click "Already have it? Point us to it".
4. Paste in the folder path where that language is installed, then save.

This is expected and the app is safe - it's a one-person, free project without a paid certificate to silence this warning on every operating system yet.

On Windows:

1. If you see "Windows protected your PC," click More info.
2. Then click Run anyway.
3. If your antivirus flags it too, choose Allow or Install anyway.

On Linux:

1. Open a terminal in your Downloads folder.
2. Paste this and press Enter: chmod +x INDEX0*.AppImage && ./INDEX0*.AppImage
3. If a "Trust this executable?" popup appears instead, just click through it.

You'll only need to do this once per download - it won't ask again after that.

1. Check that your internet connection is working.
2. Click Cancel on the stuck download.
3. Click the download option again to retry - it doesn't start over from zero every time.
4. Still stuck? Click Skip for now to get into the app, then try again later from the gear icon in the top right corner of your app.

1. Click the gear icon in the top right corner of your app.
2. Find the section called "Zero's model".
3. Pick a different tab (Ollama, Claude, ChatGPT, Gemini, or Custom) and set it up.
4. It switches instantly - nothing else about the app changes.

By default, nothing ever leaves your computer. INDEX 0 runs fully offline using Ollama.

If you choose to use your own ChatGPT, Claude, or Gemini key instead, then only your messages to Zero are sent to whichever one company you picked - never to anyone else, and never your personal files or anything outside that conversation.

An optional check after each lesson, so you know what actually stuck.

1. Open any course (ML/AI, Electronics, System Design, Cybersecurity, or Python).
2. Find the Quiz Mode toggle switch and turn it on.
3. Finish a lesson, and a short quiz appears - some multiple choice, some short answer, graded by Zero.

1. Go to that lesson's section list (where all the lessons in that chapter are shown).
2. Find the orange number next to the lesson you want to undo.
3. Click it, then confirm Unmark when asked.

For a DSA problem you solved by mistake or want to redo, click the green checkmark on that problem's tile the same way.

Yes, with the optional Sync feature.

1. Click the gear icon in the top right corner of your app.
2. Find the Sync section at the top and turn it on.
3. Create a free account with just an email and password.
4. Do the same on your other computer and sign in with the same account.

This is entirely optional - the app works completely fine on one computer with sync left off.

The app checks for updates on its own every time you open it - you don't need to check manually. Look at the small badge near the top of the app:

1. "Up to date" - you're already on the newest version, nothing to do.
2. "Download Update" - a new version exists. Click it to start downloading.
3. "Downloading... X%" - it's downloading in the background, you can keep using the app.
4. "Restart to update" - the update is ready. Click it, and the app closes, installs it, and reopens by itself.

If you click "Restart to update" and it still shows "Restart to update" after reopening:

1. This link always points to the newest version, whenever you open it:
   Open the downloads page →
2. Download the installer for your computer and run it right over your current install.
3. None of your progress is lost. Every solved problem, lesson, and setting stays exactly as it is - reinstalling only replaces the app itself.