Check Digit Validator

Validates IBAN/ISBN/EAN/Luhn checksums and finds the one wrong digit

Connector by gumballtools.com · Domain verified by the MCP Registry

IndexedLicense unknownRemote (HTTP)

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Install

Works with Claude Code, VS Code, Cursor, Windsurf. Read the repository before you give any tool access to your data.

npx agentmarket install connector/gumballtools-com-check-digit

Asks which of your tools to add it to (Claude Code, Codex, Cursor, VS Code, Windsurf, Gemini CLI, Claude Desktop) and shows the change first. See https://agentmart.dev/cli.

Remote endpoint

https://check-digit.gumballtools.com/api/mcp Remote (HTTP)

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About

Validates IBAN/ISBN/EAN/Luhn checksums and finds the one wrong digit

Reviews

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Permissions

What this server can do and what it asks for, from its tool list and install config. Checked Oct 25, 2026.

Tools: 1 read · 0 write · 0 deleteRead-only
Secrets: None asked for
Install scripts: Nothing to install (hosted)
Runs as: Hosted (remote endpoint)

Tools by what they do 1

From the running server's own tool list (tools/list) on Oct 25, 2026.

Read 1 · Look things up without changing anything.

run

Network hosts it talks to 1

check-digit.gumballtools.com · found in remote endpoint, install command

Tools (1)

As the server listed them on Oct 25, 2026. Descriptions are the server’s own words; hidden characters are shown as [U+…].

runCheck Digit Validatorread-only
Validate the check digit(s) on an IBAN, ISBN-10, ISBN-13, EAN-13, UPC-A, or Luhn-checked card number, and when it fails, try to say which digit is wrong. Use this instead of computing the checksum yourself. Mod-97 arithmetic on a rearranged 15-34 character IBAN, or a weighted sum mod 10/11 over 10-19 digits, is exactly the kind of long deterministic calculation language models get wrong silently and confidently — there is no way for a reader to tell a fabricated "valid" from a real one without redoing the math. This tool actually redoes the math, and when the checksum fails, searches for the …

Signals

Last release: Sep 5, 2026 (1 month ago)
Repository: Not found on GitHub (deleted or private)

Details

Registry name: com.gumballtools/check-digit
Version: 0.1.0
Auth: Auth not stated
License: License unknown
Repository: github.com/bwalvoord/gumball
Website: check-digit.gumballtools.com
First seen: Oct 24, 2026
Last checked: Oct 24, 2026
Source: Official MCP Registry

Rank

of 44,833 in Connectors

Score

0.537

Security 30%not yet
Popularity 25%0.30
Freshness 20%0.80
Rating 15%not yet
Docs 10%0.77

How ranking works →

Grades

Freshness

Active in the last 90 days. Last activity 1 month ago.

–

Security

Security scan: in progress. Grades from our dependency, secret, code and prompt-injection checks appear here once they launch. Until then, check the code before you install.

Indexed

Found automatically from a public source. Not yet claimed by its publisher.

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Availability

100% uptime, last 30 days (1 check)

Last check: 6 days ago
Status: Up
Median response: 1.4 s

Up
Up, auth required
Down
Not checked
No data

A daily MCP handshake with the remote endpoint. “Auth required” means it answered and wants a login or key. “Not checked” means the URL needs your own account or blocks automated checks.

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Cite this page

Check Digit Validator MCP server. Agent Mart. https://agentmart.dev/connectors/gumballtools-com-check-digit (last updated 2026-10-24)