UUID v4 API

Request parameters

Response fields

A successful response is {"ok":true,"data":{…}}. These fields are inside data.

values · array

Fresh UUID version 4 strings.

Allocate identifiers in a script

This endpoint returns UUID version 4 strings generated by the runtime’s cryptographic random-number generator. It is useful for small batches in fixtures or automation that need standard UUID formatting. Most programming environments can also generate UUIDs locally; use the API when a uniform HTTP integration is more convenient.

Randomness and retries

Each successful call generates new values, including when the same request is retried. The API is not idempotent and does not reserve or persist identifiers. Version 4 UUIDs are probabilistically unique, not a database uniqueness guarantee. The output uses lowercase hex with hyphens. Other UUID versions, shortened identifiers and custom prefixes are not supported.

cURL, JavaScript and Python examples

curl --fail-with-body --request POST 'https://www.base64.sh/api/v1/uuid-generator/' \
  --user-agent 'Base64.sh API example/1.0' --header 'Content-Type: application/json' \
  --data-raw '{}'

const response = await fetch("https://www.base64.sh/api/v1/uuid-generator/", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({})
});
if (!response.ok) throw new Error(await response.text());
console.log(await response.json());

import json
from urllib.request import Request, urlopen

payload = json.loads("{}")
request = Request(
    "https://www.base64.sh/api/v1/uuid-generator/",
    data=json.dumps(payload, ensure_ascii=False).encode("utf-8"),
    headers={"Content-Type": "application/json", "User-Agent": "Base64.sh API example/1.0"},
    method="POST",
)
with urlopen(request, timeout=15) as response:
    print(json.load(response))

{
  "ok": true,
  "data": {
    "values": [
      "123e4567-e89b-42d3-a456-426614174000"
    ]
  }
}

curl --fail-with-body --request POST 'https://www.base64.sh/api/v1/uuid-generator/' \
  --user-agent 'Base64.sh API example/1.0' --header 'Content-Type: application/json' \
  --data-raw '{"count":3}'

const response = await fetch("https://www.base64.sh/api/v1/uuid-generator/", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
  "count": 3
})
});
if (!response.ok) throw new Error(await response.text());
console.log(await response.json());

import json
from urllib.request import Request, urlopen

payload = json.loads("{\n  \"count\": 3\n}")
request = Request(
    "https://www.base64.sh/api/v1/uuid-generator/",
    data=json.dumps(payload, ensure_ascii=False).encode("utf-8"),
    headers={"Content-Type": "application/json", "User-Agent": "Base64.sh API example/1.0"},
    method="POST",
)
with urlopen(request, timeout=15) as response:
    print(json.load(response))

{
  "ok": true,
  "data": {
    "values": [
      "123e4567-e89b-42d3-a456-426614174000",
      "123e4567-e89b-42d3-a456-426614174001",
      "123e4567-e89b-42d3-a456-426614174002"
    ]
  }
}

Invalid request example

{
  "count": 101
}

HTTP 400

{
  "ok": false,
  "error": {
    "code": "INVALID_INPUT",
    "message": "count must be between 1 and 100."
  }
}

Limits and error handling

Requests require Content-Type: application/json and a UTF-8 JSON object. The body limit is 32 KiB (32,768 bytes), text fields allow up to 16,384 Unicode code points unless a smaller limit is listed, and responses are limited to 256 KiB. Unknown parameters and unpaired Unicode surrogates in parameter strings are rejected. Send inputs in the request body, not query parameters.

Anonymous access is limited to approximately 60 POST requests per minute per IP address, shared across endpoints in each Cloudflare location. Shared networks share the allowance. Counters are eventually consistent, not a guaranteed global quota. On HTTP 429, wait for the Retry-After interval before retrying; avoid immediate retry loops.

Programmatic clients should send an identifying User-Agent, as shown in the cURL and Python examples. Browser fetch supplies its own header. Cloudflare may reject a generic or missing agent before the API runs; an edge-generated 403 can be plain text or HTML rather than the JSON envelope. See Cloudflare error 1010.

400 · Invalid input

Malformed JSON, missing fields, unsupported options or invalid encoded text. Correct the input before retrying.

403 · Edge request blocked

Check the User-Agent and the Cloudflare error response before retrying.

404 · Unknown endpoint

Use a documented /api/v1/{tool}/ endpoint.

405 · Method not allowed

Use POST. OPTIONS is supported for browser CORS requests.

413 · Size limit exceeded

Reduce the request size or the generated output.

415 · Unsupported media type

Set Content-Type: application/json.

429 · Rate limited

Wait at least the Retry-After number of seconds.

500 / 503 · Service unavailable

Retry later with bounded backoff. Availability is not guaranteed.

API data processing

API inputs are sent over HTTPS and processed in memory by a Cloudflare Worker. The application does not persist submitted text or deliberately log request bodies, and API responses use Cache-Control: no-store. Cloudflare may process network metadata under its own policies. For local processing, use the corresponding browser tool. See the privacy policy.