curl --request GET \
--url https://www.closient.com/resolver/api/v1/public/gs1/analyzeimport requests
url = "https://www.closient.com/resolver/api/v1/public/gs1/analyze"
response = requests.get(url)
print(response.text)const options = {method: 'GET'};
fetch('https://www.closient.com/resolver/api/v1/public/gs1/analyze', options)
.then(res => res.json())
.then(res => console.log(res))
.catch(err => console.error(err));<?php
$curl = curl_init();
curl_setopt_array($curl, [
CURLOPT_URL => "https://www.closient.com/resolver/api/v1/public/gs1/analyze",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "GET",
]);
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}package main
import (
"fmt"
"net/http"
"io"
)
func main() {
url := "https://www.closient.com/resolver/api/v1/public/gs1/analyze"
req, _ := http.NewRequest("GET", url, nil)
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))
}HttpResponse<String> response = Unirest.get("https://www.closient.com/resolver/api/v1/public/gs1/analyze")
.asString();require 'uri'
require 'net/http'
url = URI("https://www.closient.com/resolver/api/v1/public/gs1/analyze")
http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
request = Net::HTTP::Get.new(url)
response = http.request(request)
puts response.read_body{
"check_digit": "8",
"expected_check_digit": "8",
"gs1_prefix": "950",
"is_gtin_length": true,
"is_valid": true,
"issuing_organization": "GS1 Global Office",
"length": 14,
"normalized": "09506000164908",
"value": "09506000164908"
}{
"detail": "The requested resource was not found.",
"error_code": "not_found",
"retryable": false,
"status": 404,
"timestamp": "2026-03-31T12:00:00+00:00",
"title": "Not Found",
"type": "https://closient.com/docs/errors/not_found"
}{
"detail": "The requested resource was not found.",
"error_code": "not_found",
"retryable": false,
"status": 404,
"timestamp": "2026-03-31T12:00:00+00:00",
"title": "Not Found",
"type": "https://closient.com/docs/errors/not_found"
}{
"detail": "The requested resource was not found.",
"error_code": "not_found",
"retryable": false,
"status": 404,
"timestamp": "2026-03-31T12:00:00+00:00",
"title": "Not Found",
"type": "https://closient.com/docs/errors/not_found"
}{
"detail": "The requested resource was not found.",
"error_code": "not_found",
"retryable": false,
"status": 404,
"timestamp": "2026-03-31T12:00:00+00:00",
"title": "Not Found",
"type": "https://closient.com/docs/errors/not_found"
}{
"detail": "The requested resource was not found.",
"error_code": "not_found",
"retryable": false,
"status": 404,
"timestamp": "2026-03-31T12:00:00+00:00",
"title": "Not Found",
"type": "https://closient.com/docs/errors/not_found"
}Verify a GS1 key's check digit and identify its prefix
Check the GS1 mod-10 check digit on any numeric GS1 key (GTIN-8/12/13/14, GLN, SSCC) and — for GTIN-shaped keys — report which GS1 Member Organisation or numbering scheme the prefix belongs to.
expected_check_digit is returned even when the supplied digit is wrong, because the useful answer to a failed check is which digit it should have been.
Keyless — no API key, no signup. IP-throttled at 300 requests/minute and cached at the edge for 24h, so repeat calls for the same input do not reach origin. Over-rate callers get a 429 with a Retry-After header and a retry_after field — it never silently degrades or returns a wrong answer under load.
curl --request GET \
--url https://www.closient.com/resolver/api/v1/public/gs1/analyzeimport requests
url = "https://www.closient.com/resolver/api/v1/public/gs1/analyze"
response = requests.get(url)
print(response.text)const options = {method: 'GET'};
fetch('https://www.closient.com/resolver/api/v1/public/gs1/analyze', options)
.then(res => res.json())
.then(res => console.log(res))
.catch(err => console.error(err));<?php
$curl = curl_init();
curl_setopt_array($curl, [
CURLOPT_URL => "https://www.closient.com/resolver/api/v1/public/gs1/analyze",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "GET",
]);
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}package main
import (
"fmt"
"net/http"
"io"
)
func main() {
url := "https://www.closient.com/resolver/api/v1/public/gs1/analyze"
req, _ := http.NewRequest("GET", url, nil)
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))
}HttpResponse<String> response = Unirest.get("https://www.closient.com/resolver/api/v1/public/gs1/analyze")
.asString();require 'uri'
require 'net/http'
url = URI("https://www.closient.com/resolver/api/v1/public/gs1/analyze")
http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
request = Net::HTTP::Get.new(url)
response = http.request(request)
puts response.read_body{
"check_digit": "8",
"expected_check_digit": "8",
"gs1_prefix": "950",
"is_gtin_length": true,
"is_valid": true,
"issuing_organization": "GS1 Global Office",
"length": 14,
"normalized": "09506000164908",
"value": "09506000164908"
}{
"detail": "The requested resource was not found.",
"error_code": "not_found",
"retryable": false,
"status": 404,
"timestamp": "2026-03-31T12:00:00+00:00",
"title": "Not Found",
"type": "https://closient.com/docs/errors/not_found"
}{
"detail": "The requested resource was not found.",
"error_code": "not_found",
"retryable": false,
"status": 404,
"timestamp": "2026-03-31T12:00:00+00:00",
"title": "Not Found",
"type": "https://closient.com/docs/errors/not_found"
}{
"detail": "The requested resource was not found.",
"error_code": "not_found",
"retryable": false,
"status": 404,
"timestamp": "2026-03-31T12:00:00+00:00",
"title": "Not Found",
"type": "https://closient.com/docs/errors/not_found"
}{
"detail": "The requested resource was not found.",
"error_code": "not_found",
"retryable": false,
"status": 404,
"timestamp": "2026-03-31T12:00:00+00:00",
"title": "Not Found",
"type": "https://closient.com/docs/errors/not_found"
}{
"detail": "The requested resource was not found.",
"error_code": "not_found",
"retryable": false,
"status": 404,
"timestamp": "2026-03-31T12:00:00+00:00",
"title": "Not Found",
"type": "https://closient.com/docs/errors/not_found"
}Query Parameters
The GS1 key to analyse, e.g. 09506000164908. Hyphens and spaces are ignored.
1 - 64Response
OK
Check-digit and issuing-organisation analysis of a numeric GS1 key.
The input, echoed back unchanged.
True when the key's trailing GS1 mod-10 check digit is correct.
Digit count after stripping hyphens and spaces.
x >= 014
Whether the length is one of the GTIN-8/12/13/14 lengths.
Why the key is invalid, or null when it checks out.
GTIN-length keys zero-padded to GTIN-14; other keys stripped of separators. null when the key could not be read.
The trailing digit supplied by the caller.
"8"
The digit the GS1 mod-10 algorithm requires. Populated even when it disagrees with check_digit.
The three-digit GS1 prefix (digits 2-4 of the GTIN-14). null for non-GTIN-length keys.
Which GS1 Member Organisation or scheme that prefix belongs to. null when unassigned or not GTIN-shaped.