Quick answer: ‘Free’ doubt apps are paid for by ads and by your attention. For a student solving 20 doubts at night, that is 20 interruptions. Here is why many are moving to small pay-per-question packs instead.
What ads actually cost
- Time: a 15–30 second ad per answer is 5–10 minutes per study session.
- Focus: every ad resets your attention; research on task-switching shows recovery takes minutes.
- Distraction: game and shopping ads are designed to pull you out of study mode.
- Data: free apps profile your usage to target ads.
What pay-per-question changes
- No ads, because the answer itself is the product.
- You decide the budget: ₹9, ₹49 or ₹99 packs, no auto-renewal.
- Unused credits wait in your account; failed answers refund the credit.
- Explanations in your language with diagrams, not a video you must sit through.
Cost check
| Option | Real cost of 100 doubts |
|---|---|
| Free app with ads | ₹0 + ~50 minutes of ads + distraction |
| Subscription app | ₹500–1500/month whether or not you use it |
| DoubtPay AI ₹49 pack | ₹49, no ads, no renewal |
Who should still use free apps
If you only need textbook back-exercise answers and do not mind ads, free banks are fine. Use pay-per-question for the doubts they cannot answer.
Stuck on a question? Ask it here and get a step-by-step answer in seconds — pay only per answer, no subscription. Ask your doubt now →
Related: pay-per-question vs subscription.
Stuck on a study question?
Type the exact question (or attach a photo), choose your class or exam and your language — Hindi, Hinglish, English or 9 more — and ask your doubt on DoubtPay AI. You get step-by-step working with a labelled diagram where it helps, and you can ask for a hint, an attempt check, practice questions or flashcards instead. No subscription: packs start at ₹9 for 15 answers, unused credits stay in your account.
Frequently asked questions
Is DoubtPay AI free to try?
You can try the animated tutor demo without logging in. Answers use credits, and the smallest pack is ₹9 for 15 answers. Failed answers refund the credit.
Which languages and exams does DoubtPay AI support?
Hindi, Hinglish, English, Bengali, Marathi, Tamil, Telugu, Gujarati, Kannada, Malayalam, Punjabi and Odia, for Class 6–12 (CBSE, ICSE, state boards), JEE, NEET, CUET, SSC, banking, railways, UPSC and state PSC.
Do credits expire or renew automatically?
There is no subscription and nothing renews automatically. Unused credits stay in your account while the service runs, and answers are kept in your history for 90 days.
Stuck on a question? Ask it here and get a step-by-step answer in seconds — pay only per answer, no subscription. Ask your doubt now →