ISBN

GET/v0/isbn

Validates an International Standard Book Number in both ISBN-10 and ISBN-13 formats. Verifies the check digit using the respective algorithm (mod-11 for ISBN-10, mod-10 weighted for ISBN-13). When valid, both the ISBN-10 and ISBN-13 equivalents are returned — ISBN-13 with prefix 979 has no ISBN-10 equivalent. Spaces and hyphens in the input are stripped automatically.

Try it

Query Parameters

Parameter	Type	Required	Description
value	string	Yes	The ISBN-10 or ISBN-13 number to validate (with or without hyphens)

Example Requests

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/isbn?value=978-0-306-40615-7"

Response Fields

Field	Type	Description
valid	boolean	Whether the ISBN passed check digit validation
format	string	Detected format: `ISBN-10` or `ISBN-13`
isbn10	string \| null	Normalized ISBN-10 (without hyphens). `null` when the input is ISBN-13 with prefix `979`, which has no ISBN-10 equivalent
isbn13	string	Normalized ISBN-13 (without hyphens). Always present for valid inputs

Example Response — ISBN-13

{
  "valid": true,
  "format": "ISBN-13",
  "isbn10": "0306406152",
  "isbn13": "9780306406157"
}

Example Response — ISBN-10

{
  "valid": true,
  "format": "ISBN-10",
  "isbn10": "0306406152",
  "isbn13": "9780306406157"
}

Example Response — invalid

{
  "valid": false
}