How we can know if the form entery is added by bot/tool/software or human form having google v2 captcha

Question

We are getting spam entries with vulgar words, How we can know/identify that the entries are submitted by bot or human being. Form is having google v2 captcha

Manually check the data added

Answer 1

There are several ways. I would have added below ones if I wanted to fix this for my website.

1. Keystrokes of user actions for e.g. key press and key release differences, difference between form open time and submit time.
2. Checking javascript variable navigator.webdriver if its true then its a selenium script.
3. User's IP address check. Only single form entry from one IP address.
4. Identifying user-agent of the request and blocking any invalid or outdated user-agents.

These steps won't solve 100% of the problem, but it will reduce the fake entries by some extent.