Isin compute from nsin

isin-compute-from-nsin · version 1.0.0 · Identifiers & check digits · free, no key needed

Build a 12-character ISIN from a country prefix and a CUSIP/SEDOL national number, computing its Luhn check digit.

Use when you need to: convert cusip to isin · convert sedol to isin · build an isin from a national security number.

Decide before calling

Read the versioned contract and the supported scope below. Reuse isin-compute-from-nsin@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use isin-compute-from-nsin@1.0.0 for convert cusip to isin. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• convert cusip to isin
• convert sedol to isin
• build an isin from a national security number
• compute isin check digit from cusip
• turn a uk sedol into an isin
• generate isin from nsin
• pad a sedol into an isin nsin slot

Not supported

• validating an already-complete 12-character ISIN (see isin-validate)
• computing an ISIN for a country outside US, CA, GB, IE, IM, JE, GG
• computing the CUSIP or SEDOL check digit for the caller (the national number must already be self-consistent)

Behavior

• nsin_padded is nsin left-padded with '0' to exactly 9 characters (a no-op when nsin is already 9 characters); this covers both a 9-character CUSIP unchanged and a 7-character SEDOL gaining exactly two leading zeros.
• Only country_prefix values US, CA, GB, IE, IM, JE, GG are supported; any other well-formed 2-letter value throws unsupported_input.
• For US/CA, nsin_padded must be a self-consistent CUSIP that is ISIN-eligible: its first 8 characters must each be a digit 0-9 or an uppercase letter A-Z (the CUSIP private-placement characters '*', '@' and '#' are valid in a CUSIP but never in an ISIN NSIN) and its own 9th character must equal the ANSI X9.6 check digit computed from those 8 characters; a charset violation throws invalid_input with details.reason 'cusip_invalid_character', a check-digit mismatch throws invalid_input with details.reason 'cusip_check_digit_mismatch'.
• For GB/IE/IM/JE/GG, nsin_padded's first two characters must be '00' and the remaining 7 characters must be a self-consistent SEDOL (weights 1,3,1,7,3,9 over the first 6, no vowels); a padding, charset or check-digit failure throws invalid_input.
• Once nsin_padded is accepted, check_digit is computed exactly as in isin-validate: expand country_prefix+nsin_padded (11 characters, A=10 ... Z=35) then apply Luhn (double every digit at an odd 1-based position from the right, sum, check = (10 - sum mod 10) mod 10).
• isin is country_prefix + nsin_padded + check_digit (12 characters, no case folding).

Input

• country_prefix (string, required): min length 2; max length 2; pattern ^[A-Z]{2}$
• nsin (string, required): min length 1; max length 9

Output

• isin (string, required): min length 12; max length 12
• check_digit (string, required): min length 1; max length 1
• nsin_padded (string, required): min length 9; max length 9
• data_version (string, required)

Limits

• max country prefix bytes: 2
• max nsin bytes: 9

Example

Request input:

{
  "country_prefix": "US",
  "nsin": "037833100"
}

Response:

{
  "result": {
    "isin": "US0378331005",
    "check_digit": "5",
    "nsin_padded": "037833100",
    "data_version": "isin-nsin-schemes-2026-09-28"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "isin-compute-from-nsin",
  "version": "1.0.0",
  "input": {
    "country_prefix": "US",
    "nsin": "037833100"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/isin-compute-from-nsin/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"country_prefix":"US","nsin":"037833100"}'

The machine-readable contract is at /v1/tools/isin-compute-from-nsin/versions/1.0.0.

CLI

node cli.mjs run isin-compute-from-nsin 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

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• Isin validate: Validate a 12-character ISIN's ISO 6166 Luhn check digit and parse its country prefix, NSIN and NSIN scheme.
• Rf creditor reference compute: Compute the MOD 97-10 check digits and full ISO 11649 RF Creditor Reference for a base reference (invoice number).
• Issn validate: Validate an 8-digit ISSN's mod 11 check digit (X allowed) and compute its 977-prefixed EAN-13 barcode form.
• Cn resident id parse: Parse an 18-digit (or legacy 15-digit) Chinese resident ID: region code, birth date, sex and GB 11643-1999 check digit.
• Ismn validate: Validate an ISMN's EAN mod 10 check digit in M-form or 979-0 form and return the canonical 13-digit form.