Direct answer: Libby (via your public library card) and LibriVox (volunteer-read public-domain audiobooks) are the two most reliable ways to get full audiobooks free with no subscription, credit card, or trial commitment.
Library apps: the best all-around option
Libby and hoopla, both accessible with a public library card, offer full-length professionally narrated audiobooks of current and backlist titles at zero cost. This covers the vast majority of what a paid subscription service like Audible offers, minus the newest same-day releases occasionally.
LibriVox for public-domain classics
LibriVox hosts thousands of volunteer-narrated audiobooks of public-domain works — classic literature, philosophy, and historical texts — completely free to stream or download, with no account required.
Free trials, used carefully
Paid services like Audible, Chirp, and Libro.fm occasionally offer a free first audiobook through a trial; this can be useful for a specific new release, but relying on serial trial signups isn't a sustainable long-term strategy and some services restrict repeat trials by payment method.
Podcasts and publisher samples
Some publishers and authors release full audio serials as podcasts, and many audiobook platforms offer a free sample chapter — useful for previewing narration style before committing to a library hold or purchase.
Is LibriVox audio quality as good as paid audiobooks?
It varies by narrator since LibriVox is volunteer-run, but many titles are excellent; you can preview a sample before committing.
Can I listen to library audiobooks offline?
Yes, both Libby and hoopla support downloading audiobooks for offline listening within the loan period.
Do free audiobook sites include recent bestsellers?
Library apps often do, subject to wait lists; LibriVox is limited to public-domain works, so it won't include recent titles.