How to Add Address Autocomplete in Django

What the API returns

The API wraps every response in a standard envelope. The address suggestions live in the Result field, which for autocomplete is a plain array of strings:

{
  "Id": "3f2504e0-4f89-11d3-9a0c-0305e82c3301",
  "Result": [
    "123 Main St APT 1, Andover, MA 01810-3816",
    "123 Main St APT 1, Delhi, NY 13753-1257",
    "123 Main St STE 1, Caldwell, ID 83605-5476",
    "123 Main St STE 1, Corinth, NY 12822-1010",
    "123 Main St STE 1, Delhi, NY 13753-1258"
  ],
  "ClientSessionId": null,
  "StatusCode": 200,
  "IsError": false,
  "Errors": []
}

Each suggestion includes the full street, the unit designation (APT, STE, UNIT), city, state code, and ZIP+4. The API handles abbreviations (St, Ave, Blvd) and directional prefixes (N, S, E, W) on the way in, and returns clean, standardized output. In Django you read the Result key and return that array as JSON.

Get your API key

1. Sign up at sthan.io and subscribe to the free Address Autocomplete tier
2. Open your dashboard and create an API key
3. Copy the key - it looks like sthan_live_xxxxxxxxxxxxxxxx

You get the key immediately, with no approval queue. An API key is the simplest way to authenticate: you send it as a Bearer token on every request and there is no separate login step. (If you prefer a short-lived token, there is a JWT flow covered later.)

Configure settings

pip install requests

Read the key from an environment variable in settings.py - never hardcode it in source you commit:

# settings.py
import os

STHAN_API_KEY = os.environ["STHAN_API_KEY"]
STHAN_API_BASE = os.environ.get("STHAN_API_BASE", "https://api.sthan.io")

Write the proxy view

This view sends the API key as a Bearer token, URL-encodes the query, and returns the Result array. JsonResponse(..., safe=False) lets you return a top-level list:

# addresses/views.py
from urllib.parse import quote

import requests
from django.conf import settings
from django.http import JsonResponse
from django.views.decorators.http import require_GET


@require_GET
def autocomplete(request):
    query = request.GET.get("query", "").strip()
    if len(query) < 3:
        return JsonResponse([], safe=False)

    resp = requests.get(
        f"{settings.STHAN_API_BASE}/AutoComplete/USA/Address/{quote(query)}",
        headers={"Authorization": f"Bearer {settings.STHAN_API_KEY}"},
        timeout=10,
    )
    if not resp.ok:
        return JsonResponse([], safe=False, status=502)

    body = resp.json()
    # The envelope wraps the data — suggestions are in Result
    return JsonResponse(body.get("Result", []), safe=False)

The whole integration is this one request. Everything else is plumbing to keep the key on the server and to debounce the front end.

Register the URL

The browser should call your server, and your server calls sthan.io. There are two reasons for this. First, the API does not enable CORS for browser requests, so a direct call from the page would be blocked. Second, and more important, putting your API key in client-side JavaScript would expose it to anyone who opens the network tab. The view keeps the key on the server.

# urls.py
from django.urls import path

from addresses import views

urlpatterns = [
    path("api/address/autocomplete", views.autocomplete),
]

Your front end now has a clean URL to call: /api/address/autocomplete?query=123 main st returns a JSON array of addresses, and the API key never leaves the server.

Wire up the front-end input

The last piece is a debounced input that calls your view. Debouncing matters: without it, "123 main st" fires eleven requests, one per keystroke. With a 250ms debounce, it fires one request after the user pauses. Add this to a template:

<input type="text" id="address" autocomplete="off"
       placeholder="Start typing your address..." />
<ul id="suggestions"></ul>

<script>
const input = document.getElementById("address");
const list = document.getElementById("suggestions");
let timer;

input.addEventListener("input", () => {
  clearTimeout(timer);
  const query = input.value.trim();

  if (query.length < 3) {
    list.innerHTML = "";
    return;
  }

  // Wait 250ms after the last keystroke before calling the server
  timer = setTimeout(async () => {
    const res = await fetch(
      `/api/address/autocomplete?query=${encodeURIComponent(query)}`);
    const items = await res.json();
    list.innerHTML = items.map((a) => `<li>${a}</li>`).join("");
  }, 250);
});
</script>

The browser only ever talks to /api/address/autocomplete on your own domain. No key, no CORS, no third-party script. From here you can style the list, add keyboard navigation, and fill the form fields when a user clicks a suggestion.

Alternative: JWT authentication

An API key is the simplest option and is all most apps need. If your security policy prefers short-lived credentials, the platform also supports a 2-step JWT flow. You call GET /Auth/Token once with your profileName and profilePassword headers, receive a token valid for up to 60 minutes, then send that token as the Bearer value on subsequent calls. Cache it with Django's cache framework:

import requests
from django.conf import settings
from django.core.cache import cache


def sthan_token():
    token = cache.get("sthan_token")
    if token:
        return token

    resp = requests.get(
        f"{settings.STHAN_API_BASE}/Auth/Token",
        headers={
            "profileName": settings.STHAN_PROFILE_NAME,
            "profilePassword": settings.STHAN_PROFILE_PASSWORD,
        },
        timeout=10,
    )
    result = resp.json()["Result"]
    cache.set("sthan_token", result["access_token"], timeout=50 * 60)
    return result["access_token"]

You would then build the Authorization header from sthan_token() instead of the static key. Everything else - the endpoint, the envelope, the parsing - stays the same.

Handle errors

Two status codes are worth handling explicitly so a hiccup never crashes your form:

• 401 - The key or token was rejected. Check the value and, on the JWT flow, clear the cached token and retry once.
• 429 - Rate limit reached. Back off and return what the user has typed so far rather than throwing.

if resp.status_code == 429:
    # Rate limited — degrade gracefully, don't crash the form
    return JsonResponse([], safe=False)

Returning an empty list on failure means a momentary hiccup shows no suggestions rather than a broken page. The user can still type the address by hand.

What's next: confirm the address is deliverable

Autocomplete gets the user to a clean, well-formed address fast. It does not, on its own, confirm that mail or a package will actually arrive there - a suggestion can be correctly formatted yet point at a unit that no longer accepts delivery.

The natural next step is to run the chosen address through the Address Verification API at the moment the user submits the form. It returns a Delivery Point Validation (DPV) result and a deliverable status, standardizes the address to standard postal format, and appends ZIP+4 and county. The call is the same pattern you already built - one GET, the same envelope:

resp = requests.get(
    f"{settings.STHAN_API_BASE}/v2/address-verification/usa/speculative/{quote(selected)}",
    headers={"Authorization": f"Bearer {settings.STHAN_API_KEY}"},
    timeout=10,
)
result = resp.json()["Result"]
# result["deliverableStatus"], result["dpvConfirmation"]

Address Verification has its own free tier of 100 requests/month, with paid plans from $12/month. Pairing autocomplete (volume, real-time, as the user types) with verification (one confirming call at submit) keeps your costs low and your delivery data clean. Prefer Flask? See the companion Python / Flask autocomplete tutorial.