CAS Number Validator

Validate CAS Registry Numbers. Checks format, digit ranges, and the check digit algorithm.

What this tool checks

Checks

  • Format: three groups separated by hyphens (XXXXXXX-XX-X)
  • First part: 2-7 digits
  • Second part: exactly 2 digits
  • Third part: exactly 1 digit (the check digit)
  • Check digit validation using the CAS algorithm

Does not check

  • Whether the CAS number is actually registered
  • Substance name, classification, or hazard information
  • Whether the CAS number is deprecated or superseded
  • EC number or EINECS cross-references

CAS data still scattered across SDS files?

Rastro's chemical compliance AI agent validates CAS numbers, pulls substance data out of SDS documents, and flags gaps before they turn into customer or regulatory problems.

See it on my data

Related guides