Before you pick software, decide which classifieds model you are building. The two are not the same product.
A classic classifieds board is free to list and free to browse. Sellers post, buyers email or call, and the deal happens off the site. Craigslist and Osclass work this way. Nobody pays through the platform, so the operator earns from listing fees or ads, not from the sale.
A transactional classifieds marketplace keeps the browse-by-category listings but moves the payment on-site. Buyers check out, the operator takes a commission, and each seller gets paid. This is where online marketplaces like Craigslist are quietly heading: Facebook Marketplace, OfferUp, and Mercari all added on-platform checkout, while Craigslist's free-listings revenue slid from roughly $1.04 billion in 2018 to about $302 million in 2024 (ResearchAndMarkets 2025 Craigslist Report).
Garnet builds the second kind. If you want a pure free ads board with no on-site payment, use a classifieds script instead. If you want a listings marketplace where transactions and money stay on your platform, keep reading.