CAS Number
GET/v0/cas
Validates a CAS Registry Number — a unique identifier assigned by the Chemical Abstracts Service to every chemical substance. The format is XXXX-XX-X where the last digit is a check digit computed as a weighted sum modulo 10. Hyphens and spaces are stripped automatically.
Try it
Query Parameters
| Param | Type | Required | Description |
|---|---|---|---|
| value | string | Yes | CAS number to validate (e.g. 7732-18-5 or 7732185) |
Example Request
curl -H "Authorization: Bearer YOUR_API_KEY" \ "https://api.isvalid.dev/v0/cas?value=7732-18-5"
Response Fields
| Field | Type | Description |
|---|---|---|
| valid | boolean | Whether the CAS number has a valid check digit |
| formatted | string | CAS number in standard hyphenated format |
| error | string | Error message when invalid |
Example Response — Water
{
"valid": true,
"formatted": "7732-18-5"
}Example Response — Ethanol
{
"valid": true,
"formatted": "64-17-5"
}