ULID Generator API Reference

Overview

ULID Generator works by combining a timestamp component (10 characters) with random data (16 characters) using Crockford's Base32 alphabet. Results are case-insensitive, sortable, and URL-safe.

Endpoint

One host, one path per API. The block below shows this call in four languages; every one of them is the same HTTP request. Making requests covers the timeouts, retries and parameter rules that apply to all of them. The SDKs wrap the same call in a typed client.

GEThttps://api.apiverve.com/v1/ulidgenerator

curl "https://api.apiverve.com/v1/ulidgenerator?count=5&timestamp=1609459200000" \
  -H "x-api-key: your_api_key_here"

const res = await fetch('https://api.apiverve.com/v1/ulidgenerator?count=5&timestamp=1609459200000', {
  headers: { 'x-api-key': 'your_api_key_here' },
});

if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);

const { data } = await res.json();
console.log(data);

import requests

res = requests.get(
    "https://api.apiverve.com/v1/ulidgenerator?count=5&timestamp=1609459200000",
    headers={"x-api-key": "your_api_key_here"},
    timeout=15,
)
res.raise_for_status()

print(res.json()["data"])

package main

import (
	"fmt"
	"io"
	"net/http"
)

func main() {
	req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/ulidgenerator?count=5&timestamp=1609459200000", nil)
	req.Header.Set("x-api-key", "your_api_key_here")

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()

	out, _ := io.ReadAll(res.Body)
	fmt.Println(string(out))
}

Replace your_api_key_here with the key from your dashboard. When the inputs arrive as a list rather than one at a time, batch requests run up to 200 of them through this same API in a single call.

Authentication

Send your key in the x-api-key header. That is the only auth step — there is no token exchange and no per-endpoint scope to configure. Authentication covers creating, rotating and revoking keys.

401 is the only auth verdict

A 401 means the key is missing, invalid or expired. A 403 means the key is valid but not permitted here — blocked by a key restriction or an IP allow-list. Running out of credits is a 429.

Parameters

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them.

Parameter	Type	Description
`count`Optional	integer	Number of ULIDs to generate default 1 · range 1–100
`timestamp`Optional	integer	Custom timestamp in milliseconds (optional, uses current time if not specified)

Response

Every API returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape. Response format covers the envelope, the other output formats and how premium fields are withheld.

Sample response

{
  "status": "ok",
  "error": null,
  "data": {
    "ulids": [
      "01KCMMK564DMMCC17AVBZTVNT1",
      "01KCMMK565ZE4681DFAEWBF95G",
      "01KCMMK566K1REYH0JEK4Q8DKW",
      "01KCMMK5670W9EHFNX76R8FKWH",
      "01KCMMK568SFRY6DCZTZYMR66Y"
    ],
    "count": 5,
    "timestamp": 1765924246724,
    "format": "26 characters (10 timestamp + 16 random)",
    "sortable": true,
    "case_insensitive": true
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Field	Type	Example	Description
`ulids`	array	`[01KCMMK564DMMCC17AVBZTVNT1, ...]`	Array of generated ULID strings in proper format
`count`	number	`5`	Number of ULIDs generated in this request
`timestamp`Premium	number	`1765924246724`	Timestamp in milliseconds used for generation
`format`	string	`"26 characters (10 timestamp + 16 random)"`	ULID format specification and component breakdown details
`sortable`	boolean	`true`	Whether generated ULIDs maintain natural chronological sorting
`case_insensitive`	boolean	`true`	Whether ULIDs are case-insensitive for comparison purposes

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change. Error handling covers the full status list and which of them are worth retrying.

Status	Meaning	What to do
`400`	Input was rejected	Read `error`; it names the parameter.
`401`	Key missing or invalid	Check the header name and the key value.
`403`	Key valid, but not permitted	A key restriction or IP allow-list; see key scoping.
`429`	Rate limited, or out of credits	Read `error` to tell them apart; see rate limits.

Use cases

Database Keys: Generate sortable primary keys for databases that maintain chronological order
Distributed Systems: Create unique identifiers across distributed systems with time-based sorting
Log Aggregation: Generate sortable IDs for log entries and event tracking systems
API Resources: Create resource identifiers that reveal creation time and sort naturally

Other ways to use ULID Generator

Set up ULID Generator on APIVerve, or reach the same source a different way. Your APIVerve account and credits work on all of them — one key, one balance.

Give it to an AI agentConnect over MCP and your agent calls it as a native tool — Claude, Cursor, ChatGPT.VerveKit →Reference →

Use it in Google Sheets or ExcelA =VERVE() formula fills a column — no script, no export, recalculates in place.VerveSheets →Reference →

ULID Generator