Kavra LabWhat makes a bot bad
A bad bot has two traits: it hides what it is, and it takes something the site did not mean to give it. It may claim to be Chrome on a laptop while running on a server, borrow the name of a search crawler, or rotate through thousands of home IP addresses so rate limits never trigger. The goal is always to act at a scale no single person could, while looking like many ordinary people.
Operators rent these bots as a service or buy ready-made kits for a specific site, complete with proxy lists, spoofed device profiles and CAPTCHA-solving add-ons. That lowers the skill needed to attack a login or a promotion to almost nothing, which is why a campaign can start the same day a new offer goes live.
Types of bad bots and what they target
| Bad bot | Where it strikes | What you lose |
|---|---|---|
| Credential stuffing bot | Login | Customer accounts, support time, trust |
| Web scraping bot | Product, price and search pages | Pricing edge, content, server capacity |
| Fake account bot | Signup | Bonus and trial budgets, clean data |
| Scalping bot | Cart and checkout | Limited stock sold to resellers |
| Card testing bot | Payment form | Fees, chargebacks, processor standing |
| SMS pumping bot | OTP and phone verification | Messaging bill |
| Impostor crawler or agent | Anywhere a good bot is allowed | Access meant only for verified bots |
How bad bots show up in real traffic
Sophisticated bad bots rarely look like a flood from one address. They look like a slightly busier day: signups that are a little too regular, logins from many cities that fail at the same rate, product pages read in perfect order, carts filled seconds after a drop. The damage appears later as account takeover complaints, bonus costs that do not match growth, or competitors matching your prices within minutes.
- Traffic from residential or mobile proxy networks rather than data centers.
- Browsers that claim one device but behave like another, often a headless browser.
- A new device fingerprint on every visit from what is really one actor.
- Input that is too fast, too even or missing altogether.
- Declared crawlers or AI agents arriving from outside their operator's IP ranges.
How to stop bad bots
CAPTCHAs and IP blocklists each check one thing, and bad bots are built to pass exactly that thing. Stopping them takes evidence from several layers compared at once, and a decision at the endpoints that matter. Kavra analyzes 3,000+ data points per visit, looks for contradictions between layers, and tells your backend whether to allow, verify or block, without puzzles for real customers. Start with headless browser detection or see how it stops web scraping. For the other side of the line, read what makes a good bot.