How to detect and block bot traffic on your website
Updated:
Quick answer
Bot traffic shows up as sudden spikes with no matching sales, many sign-ups from one network, failed logins in bursts and form submissions with identical or random content. Block it in layers: separate good bots from bad with verification, rate-limit by IP and account, protect forms with a low-friction CAPTCHA, validate on the server and monitor the numbers weekly. No single control stops everything.
What is bot traffic?
Bot traffic is any request made by software instead of a person. Some of it is useful: search engine crawlers, uptime monitors and feed readers. A lot of it is not: scrapers, spam bots, credential-stuffing tools and fake sign-up scripts.
OWASP catalogues these as automated threats to web applications, including account creation, credential stuffing, scraping and card testing.
How do I recognise bot traffic?
- Traffic spikes with no matching rise in orders, sign-ups or revenue.
- Many requests from one IP address, one network range or one user agent.
- Bursts of failed logins, often against many different accounts (credential stuffing).
- New accounts with random names or throwaway email addresses.
- Form submissions with identical text, links or gibberish.
- Requests that never load images, scripts or CSS and go straight to forms or APIs.
- Sessions of zero seconds, or unusually perfect timing between actions.
Good bots versus bad bots
| Type | Examples | What to do |
|---|---|---|
| Good bots | Search engine crawlers, uptime monitors. | Allow them. Verify claims of identity, because the user agent is easy to fake. |
| Scrapers | Price and content copying. | Rate-limit, require login for valuable data, challenge suspicious clients. |
| Spam and fake sign-up bots | Contact form spam, fake accounts. | Protect forms with a bot check and verify emails. |
| Credential-stuffing tools | Stolen passwords tried at scale. | Rate-limit logins, add a challenge after failures, offer multi-factor authentication. |
A layered way to block bots
- Put a bot check on the forms and endpoints bots abuse, with the lowest friction that works.
- Verify every token on your server. Never trust a check that only runs in the browser.
- Rate-limit by IP, by account and by email address, and return 429 Too Many Requests when a limit is hit.
- Add progressive challenges: normal visitors pass silently, suspicious ones get a harder task.
- Use multi-factor authentication and breached-password checks for logins.
- Review logs and analytics weekly, and compare before and after every change.
How BurgCaptcha helps
BurgCaptcha runs proof-of-work in the browser plus request risk signals. Real visitors see no puzzle, bots pay a computing cost on every request, and no cookie is set.
Start on the free plan with up to 1,000 requests a month and measure the effect on one form first.
Frequently asked questions
How can I tell if my website has bot traffic?
Look for traffic spikes with no matching sales, bursts of failed logins, many sign-ups from one network and form submissions with identical or random content. Server logs and analytics usually show it.
Does blocking bots hurt my SEO?
Not if you let verified search engine crawlers through. Block or challenge only unverified automated traffic, and never block crawlers by user agent alone, because it can be faked.
Is a CAPTCHA enough to stop bots?
It stops many simple and mid-level bots, but it works best together with server-side validation, rate limiting and monitoring.
What is credential stuffing?
Attackers take username and password pairs leaked elsewhere and try them against your login at scale. Rate limits, challenges and multi-factor authentication reduce the damage.
How many bots are on the internet?
Reliable figures differ by source and year, so check a current report before you quote a number. What matters for you is the share of bots on your own site, which you can measure from your logs.