HTTP User Agent Is Bot Calculator

Bounded heuristic based on a spoofable User-Agent bot token pattern match, not reliable device/identity/automation classification or security/authentication decision. Empty string matches false, no network or parser claim.

Description

Bot-related User-Agent strings are useful hints but can be spoofed or absent.

Bot-related User-Agent strings are useful hints but can be spoofed or absent.^[1]

This tool reports a bounded case-insensitive pattern match without identifying the requester or making a security decision.

When to use HTTP User Agent Is Bot Calculator

Use this tool to review a bounded case-insensitive pattern match without identifying the requester or making a security decision.

How to use HTTP User Agent Is Bot Calculator and how it works

Prepare actualUserAgentHeader, with the units, conventions and assumptions below.
Enter the required fields and run HTTP User Agent Is Bot Calculator.
Read result.heuristicPatternMatch using the output definitions below.
Correct any rejected inputs and rerun; interpret the result within the stated model and its assumptions.

Input field	Meaning	Value type	Requirement
actualUserAgentHeader	Supplied User-Agent header value; carriage returns and line feeds are rejected.	string	Required; other constraints below

Enter a User-Agent string without carriage returns or line feeds. Match Googlebot, Bingbot, DuckDuckBot, Baiduspider, YandexBot, Slurp, crawler, spider or bot as case-insensitive substrings. Empty text returns false. A matching string is not bot identity verification, and ordinary text containing a matched substring can also return true.

value=caseInsensitiveSubstringMatch(userAgent,listedBotMarkers)

Apply the input ordering, units and branch conditions stated above.

Output field	Meaning	Value type
result	Object containing the calculated or selected fields below.	object
result.heuristicPatternMatch	True when a listed case-insensitive substring occurs; false is a successful unmatched input.	boolean

json

{
  "input": {
    "actualUserAgentHeader": "Go ogle bot/2.1 Mobile"
  },
  "output": {
    "result": {
      "heuristicPatternMatch": true
    }
  }
}

Limitations and assumptions

The calculation uses the supplied observations and model inputs. It does not collect measurements, select a reference population or coefficient, or establish that the model applies to the actual case. The stated branch conditions and output units remain part of the result.

All fields require explicit values. Unexpected fields, wrong types, nonfinite numbers and sparse arrays are rejected. Alignment, bounds and supported-token rules are explained above; extremely large inputs or nonfinite results can also fail. Input errors differ from successful false comparisons, unavailable-domain flags and empty match lists.

RFC 9110 describes User-Agent information identifying the originating software. This tool treats that supplied text as a heuristic signal rather than verified bot identity.^[2]

Alternative or Complementary methods

Use HTTP User Agent Is Mobile Calculator for a complementary operation: A User-Agent header is a caller-controlled string, so a token match provides only a device hint.

Use Subtitle Line Length Calculator for a complementary operation: Unicode code-point count differs from grapheme count and from rendered subtitle width.

References

HTTP User Agent Is Bot Calculator — tool.io
IETF RFC 9110: User-Agent — IETF

Similar or alternative tools

HTTP User Agent Is Mobile Calculator
A User-Agent header is a caller-controlled string, so a token match provides only a device hint.
Subtitle Line Length Calculator
Unicode code-point count differs from grapheme count and from rendered subtitle width.