Graded readers are a good resources for extensive reading, at least for people who are not yet sufficiently proficient to read texts written for native speakers of the target language.
What are good (preferably free) online graded reader resources for English?
As suggested in comments, I looked on ELL, and I found only two suggestions, both closed questions:
- Tips for easy-to-read unabridged English fiction - promoting Wizard of Oz, local public libraries (unlikely, if English is L2) and project Guttenberg
- Improving reading skills - recommending "Start with books for a younger audience" - which are native young speakers, not L2 learners.
So obviously people on ELL know their English, but do not know how to learn it better. We do. :-)