Punycode Converter API Reference

Overview

Essential for working with international domain names containing non-ASCII characters like accents, Chinese, Arabic, or Cyrillic. It also detects homograph spoofing — flagging domain labels that mix writing systems (for example a Latin 'a' swapped for a visually identical Cyrillic one), the technique behind look-alike phishing domains.

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/punycode

curl "https://api.apiverve.com/v1/punycode?text=m%C3%BCnchen.de&mode=encode" \
  -H "x-api-key: your_api_key_here"

const res = await fetch('https://api.apiverve.com/v1/punycode?text=m%C3%BCnchen.de&mode=encode', {
  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/punycode?text=m%C3%BCnchen.de&mode=encode",
    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/punycode?text=m%C3%BCnchen.de&mode=encode", 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
`text`Required	string	Unicode text or domain to encode (max 1000 characters) length 0–1000
`mode`Optional	string	Conversion mode `encodedecode` default encode

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": {
    "input": "münchen.de",
    "output": "xn--mnchen-3ya.de",
    "mode": "encode",
    "isIDN": true,
    "scripts": [
      "Latin"
    ],
    "mixedScript": false
  }
}

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
`input`	string	`"münchen.de"`	Original Punycode text provided for decoding conversion
`output`	string	`"xn--mnchen-3ya.de"`	Decoded Unicode text converted from Punycode format
`mode`	string	`"encode"`	Conversion mode used for the transformation operation
`isIDN`Premium	boolean	`true`	Indicates if result is valid internationalized domain name
`scripts`	array	`[Latin]`	Writing systems (Latin, Cyrillic, Greek, Han, etc.) detected in the domain's non-ASCII labels. Empty for a plain ASCII domain; a single entry for a legitimate international domain
`mixedScript`Premium	boolean	`false`	True when a single domain label mixes writing systems in a way no real language does (e.g. Latin combined with Cyrillic) — the signature of a homograph / look-alike phishing domain. Legitimate combinations such as Japanese (Han + Hiragana/Katakana) are not flagged. Detects cross-script spoofs, not same-script look-alikes

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

Domain Registration: Verify and convert international domain names
Web Development: Handle IDN domains in applications
Email Systems: Process internationalized email addresses
Security: Detect homograph attacks using similar-looking Unicode characters

Other ways to use Punycode Converter

Set up Punycode Converter 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 →

Punycode Converter