How to read PDFs aloud on iPhone for free

For your requirements, I would narrow the comparison to Speak Screen, Speech Central, and NaturalReader first. They address different parts of the problem: Apple provides a built-in free starting point, Speech Central offers a limited free version with a one-time upgrade, and NaturalReader documents both PDF reading and camera-based OCR.

Use the same short test for each:

1. Try a normal PDF with selectable text.

2. Listen across a page break and check the reading order.

3. Switch apps and lock the screen.

4. Test scanned material separately.

5. Check the actual free allowance and any upgrade requirement.

That will tell you more than a voice demo or the “Free” label on an App Store page. In particular, a subscription-free app can still require a purchase, and a free download can still have paid listening features.

The official listings for Speech Central and NaturalReader make those pricing distinctions visible.