Upu s10 validate

upu-s10-validate · version 1.0.0 · Identifiers & check digits · free, no key needed

Validate a 13-char UPU S10 postal identifier's weighted mod-11 check digit, split service indicator and country.

Use when you need to: validate a upu s10 tracking number · check digit for an international postal item · is this tracking number valid s10.

Decide before calling

Read the versioned contract and the supported scope below. Reuse upu-s10-validate@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 upu-s10-validate@1.0.0 for validate a upu s10 tracking number. 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

• validate a upu s10 tracking number
• check digit for an international postal item
• is this tracking number valid s10
• split a postal tracking number into service indicator and country
• verify an ems or registered mail barcode checksum
• s10 postal identifier check digit calculator

Not supported

• a live UPU or carrier tracking-status lookup
• decoding the service indicator to a human-readable mail class
• validating a domestic (non-S10) tracking number format

Behavior

• item_id is taken exactly as given: no trimming, no case folding. Length != 13 returns reason wrong_length; length 13 but not matching ^[A-Z]{2}[0-9]{9}[A-Z]{2}$ returns reason invalid_character; both leave service_indicator/serial/check_digit/country null.
• service_indicator = item_id[0:2], serial = item_id[2:10], check_digit = item_id[10], country = item_id[11:13], populated once length and charset pass.
• country is looked up against the pinned officially-assigned ISO 3166-1 alpha-2 list (data_version iso3166-1-2026-09-28); an unlisted code returns reason unknown_country without computing the check digit.
• Weighted sum over the 8 serial digits: weight = [8, 6, 4, 2, 3, 5, 9, 7]. remainder = sum mod 11; expected check digit is 5 when remainder is 0, 0 when 11-remainder is 10, else 11-remainder.

Input

• item_id (string, required): min length 1; max length 13

Output

• valid (boolean, required)
• reason (one of null, "wrong_length", "invalid_character", "unknown_country", "check_digit_mismatch", required)
• service_indicator (string or null, required): pattern ^[A-Z]{2}$
• serial (string or null, required): pattern ^[0-9]{8}$
• check_digit (string or null, required): pattern ^[0-9]$
• country (string or null, required): pattern ^[A-Z]{2}$
• data_version (constant "iso3166-1-2026-09-28", required)

Limits

• max item id bytes: 13

Example

Request input:

{
  "item_id": "LT284905264NL"
}

Response:

{
  "result": {
    "valid": true,
    "reason": null,
    "service_indicator": "LT",
    "serial": "28490526",
    "check_digit": "4",
    "country": "NL",
    "data_version": "iso3166-1-2026-09-28"
  }
}

How to call it

MCP

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

{
  "id": "upu-s10-validate",
  "version": "1.0.0",
  "input": {
    "item_id": "LT284905264NL"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/upu-s10-validate/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"item_id":"LT284905264NL"}'

The machine-readable contract is at /v1/tools/upu-s10-validate/versions/1.0.0.

CLI

node cli.mjs run upu-s10-validate 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

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