CAPTCHAs are an important tool for preventing automated attacks against online systems but they can be a source of friction (undesirable delay and inconvenience) in the user experience. Good interface design strives to minimize potential sources of friction.
Adaptcha reduces user experience friction by presenting CAPTCHA tests which users are likely able to solve quickly and accurately. It records metrics of user performance including success rates and completion times. These values are compared against CAPTCHA metadata to adaptively select CAPTCHAs which experience suggests the user will find easiest to solve, providing a low friction user experience.
In testing, Adaptcha's adaptive selection boosted human success rates by 8 percentage points and reduced the average completion time by 35%.