What's the best Android app to automatically block spam calls without paying?

Call Block is specifically designed to handle spam call filtering without requiring payment before use. The app operates by scanning incoming calls against known spam databases and allows users to customize blocking rules. Users can choose to block all calls except those from contacts, effectively eliminating unwanted interruptions from telemarketers and robocalls. The interface receives consistent praise for being straightforward and non-intrusive, with clear blocking options that require minimal configuration. Reviews indicate the blocking functionality works reliably once configured, though some users note that initial setup may take a few minutes to optimize for specific needs. Unlike many competitors in this space, Call Block doesn't display ads during normal operation, which contributes to a cleaner user experience. One limitation worth noting is that the app's effectiveness can depend on regional spam databases, which may vary in comprehensiveness. For basic spam protection without financial commitment, Call Block delivers on its core promise with minimal friction.