# ISBN checker

- Human page: https://happytails.ai/en/education-tools/isbn-checker/
- Markdown: https://happytails.ai/en/education-tools/isbn-checker.md
- Structured JSON: https://happytails.ai/agents/en/education-tools/isbn-checker/index.json
- Visibility: public

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `isbn-checker` |
| Category | education-tools |
| Implementation | Registered implementation. Registration alone is not a production-quality guarantee. |
| Browser execution | Automatic updates after valid input or file selection. |
| Browser processing | Browser; see tool notes for network behavior. |
| HTTP API | Not callable through HTTP. |
| Browser-agent interface | run_current_tool |

### Implementation notes

Enter one ISBN-10 or ISBN-13, with optional spaces or hyphens. Lowercase x is accepted as the final ISBN-10 check character. Calculate check digit expects the 9- or 12-digit body. Valid 978 ISBNs can convert between formats; 979 ISBNs cannot convert to ISBN-10. Publisher ranges, hyphen grouping and assignment are not verified. Up to 128 input characters. Runs locally.

### Inputs and settings

Text input: ISBN or ISBN body.

Example or placeholder shown in the interface (not a validated fixture):

```text
978-92-95055-02-5
```

Enter one ISBN with optional spaces or hyphens. For Calculate check digit, omit the final check character. Up to 128 characters. Results update as you type. Up to 128 characters.

| Setting | Meaning | Control type | Default | Constraints |
| --- | --- | --- | --- | --- |
| `action` | What would you like to do? | select | "Check ISBN" | Allowed: Check ISBN, Calculate check digit |

### Browser-agent workflow

1. Open the human page in a browser that supports WebMCP.
2. Discover the interface exposed by that page; use its actual schema.
3. Select files on the page first when the tool requires files.
4. Call `run_current_tool` with valid input and settings.
5. Inspect the returned result or error and the displayed output. Retrieve files from the displayed download links.

Calls do not automatically copy or download results. Browser permissions still apply. Interface availability alone is not proof of successful execution.

### Planning specification

One identifier, up to 128 characters. ASCII digits, spaces, hyphens and a final ISBN-10 X are supported. No book database, publisher-range lookup or ownership check is performed. Calculation does not allocate an ISBN. Runs on your device.

This describes intended requirements. Use the implementation notes, interface schema and observed output to determine current support.

### Complete machine-readable capability record

```json
{
  "id": "isbn-checker",
  "category": "education-tools",
  "built": true,
  "requirements": "One identifier, up to 128 characters. ASCII digits, spaces, hyphens and a final ISBN-10 X are supported. No book database, publisher-range lookup or ownership check is performed. Calculation does not allocate an ISBN. Runs on your device.",
  "implementation": {
    "fields": [
      {
        "key": "action",
        "label": "What would you like to do?",
        "value": "Check ISBN",
        "type": "select",
        "values": [
          "Check ISBN",
          "Calculate check digit"
        ]
      }
    ],
    "live": true,
    "presentation": "metrics",
    "inputMaxLength": 128,
    "inputMode": "text",
    "inputErrorCode": "IDENTIFIER_INPUT",
    "note": "Enter one ISBN-10 or ISBN-13, with optional spaces or hyphens. Lowercase x is accepted as the final ISBN-10 check character. Calculate check digit expects the 9- or 12-digit body. Valid 978 ISBNs can convert between formats; 979 ISBNs cannot convert to ISBN-10. Publisher ranges, hyphen grouping and assignment are not verified. Up to 128 input characters. Runs locally.",
    "experience": {
      "automatic": true,
      "single": true,
      "inputMaxLength": 128,
      "inputMode": "text",
      "label": "ISBN or ISBN body",
      "placeholder": "978-92-95055-02-5",
      "help": "Enter one ISBN with optional spaces or hyphens. For Calculate check digit, omit the final check character. Up to 128 characters. Results update as you type. Up to 128 characters.",
      "action": null
    },
    "mode": "automatic",
    "interactive": false
  },
  "execution": "Browser interface",
  "api": null,
  "browser_agent": {
    "supported": true,
    "name": "run_current_tool",
    "discovery": "WebMCP on the human page in a supporting browser",
    "verification": "See audit/API-AUDIT.md; availability is not verification"
  }
}
```

## Page guide

Check an ISBN-10 or ISBN-13 checksum, calculate a missing check digit, or convert between equivalent ISBN formats.

How can we improve this tool?

Report a problem or share an idea.

Please leave out private information. Your message and the tool name go to our team via PostHog.

### How to use ISBN checker

1. Choose Check ISBN or Calculate check digit.
2. Enter one complete ISBN, or its 9- or 12-digit body for check-digit calculation.
3. Review format, checksum and any available conversion, then download the JSON report.

## Useful next steps

- [Citation generator](https://happytails.ai/en/education-tools/citation-generator/) ([Markdown](https://happytails.ai/en/education-tools/citation-generator.md))

- [Barcode generator](https://happytails.ai/en/business-tools/barcode-generator/) ([Markdown](https://happytails.ai/en/business-tools/barcode-generator.md))

- [Payment card checksum checker](https://happytails.ai/en/data-tools/payment-card-checksum-checker/) ([Markdown](https://happytails.ai/en/data-tools/payment-card-checksum-checker.md))

## Check an ISBN without looking up a book

Enter one ISBN with or without spaces and hyphens. The checker accepts lowercase x as the final ISBN-10 check character. It reports format and checksum separately, so a number with the right length can still fail its check. A matching checksum does not prove that a publisher was allocated the number or that a book exists.

### Calculate a missing check digit

Choose Calculate check digit and enter the body without the final character: 9 digits for ISBN-10 or 12 digits for ISBN-13. The result supplies the check character and explains that assignment has not been verified. For a complete ISBN with a wrong checksum, the tool shows the expected character but does not silently fix or convert the number.

### Convert only where an equivalent exists

A checksum-valid ISBN-10 can be expressed as a 978 ISBN-13 with a recalculated final digit. A valid 978 ISBN-13 can convert back. ISBNs beginning with 979 have no ISBN-10 equivalent. The 979-0 prefix belongs to music identifiers and is rejected here. Publisher ranges and the placement of hyphens are not checked.