Limits, quotas and 429

curl -s -D - -o /dev/null "https://api.danadresse.dk/postnumre/8000" \
  -H "X-Api-Key: $DANADRESSE_API_KEY" | tr 'A-Z' 'a-z' | grep '^x-ratelimit'

x-ratelimit-minute-limit: 360
x-ratelimit-minute-remaining: 41
x-ratelimit-minute-reset: 1792072860
x-ratelimit-limit: 2000
x-ratelimit-remaining: 1873
x-ratelimit-reset: 1796083200

{
  "type": "RateLimitExceededError",
  "title": "The free quota of … API calls/month is used up (including the grace buffer up to … calls). …",
  "details": {
    "limit": 2000,
    "used": 2400,
    "reset_at": 1796083200,
    "resets_at": "2026-12-01T00:00:00Z",
    "upgrade_url": "https://danadresse.dk/dashboard/billing",
    "docs_url": "https://danadresse.dk/docs",
    "reason": "free_quota",
    "grace_limit": 2400
  },
  "code": "quota_exceeded"
}

import os
import random
import time

import requests

API = "https://api.danadresse.dk"
session = requests.Session()
session.headers["X-Api-Key"] = os.environ["DANADRESSE_API_KEY"]


class QuotaExceeded(Exception):
    pass


def _code(resp: requests.Response) -> str | None:
    try:
        body = resp.json()
    except ValueError:
        return None
    if not isinstance(body, dict):
        return None
    err = body.get("error")
    return err.get("code") if isinstance(err, dict) else body.get("code")


def _wait(resp: requests.Response, attempt: int) -> float:
    retry_after = resp.headers.get("Retry-After", "")
    if retry_after.isdigit():
        return int(retry_after)
    reset = resp.headers.get("X-RateLimit-Minute-Reset", "")
    if reset.isdigit():
        return max(1, int(reset) - time.time())
    return min(60, 2 ** attempt) + random.random()


def get(path: str, params: dict | None = None, attempts: int = 5) -> requests.Response:
    for attempt in range(attempts):
        resp = session.get(API + path, params=params, timeout=15)
        if resp.status_code == 429:
            if _code(resp) in ("quota_exceeded", "rate_limit_exceeded"):
                reset = resp.headers.get("X-RateLimit-Reset", "?")
                raise QuotaExceeded(f"Monthly quota used. Resets at {reset}")
        elif resp.status_code not in (502, 503, 504):
            if resp.headers.get("X-RateLimit-Minute-Remaining") == "0":
                time.sleep(_wait(resp, attempt))  # slow down before the next call
            return resp
        time.sleep(_wait(resp, attempt))
    return resp


r = get("/postnumre/8000")
r.raise_for_status()
print(r.json()["navn"], "| left this minute:", r.headers.get("X-RateLimit-Minute-Remaining"))

const API = "https://api.danadresse.dk";
const sleep = (ms) => new Promise((r) => setTimeout(r, ms));

export class QuotaExceeded extends Error {}

async function errorCode(res) {
  try {
    const body = await res.clone().json();
    return body?.error?.code ?? body?.code ?? null;
  } catch {
    return null;
  }
}

function waitMs(res, attempt) {
  const retryAfter = Number(res.headers.get("Retry-After"));
  if (retryAfter > 0) return retryAfter * 1000;
  const reset = Number(res.headers.get("X-RateLimit-Minute-Reset"));
  if (reset > 0) return Math.max(1000, reset * 1000 - Date.now());
  return Math.min(60_000, 2 ** attempt * 1000) + Math.random() * 1000;
}

export async function get(path, { attempts = 5 } = {}) {
  let res;
  for (let attempt = 0; attempt < attempts; attempt++) {
    res = await fetch(API + path, {
      headers: { "X-Api-Key": process.env.DANADRESSE_API_KEY },
      signal: AbortSignal.timeout(15_000),
    });
    if (res.status === 429) {
      const code = await errorCode(res);
      if (code === "quota_exceeded" || code === "rate_limit_exceeded") {
        throw new QuotaExceeded(`Monthly quota used. Resets at ${res.headers.get("X-RateLimit-Reset")}`);
      }
    } else if (![502, 503, 504].includes(res.status)) {
      if (res.headers.get("X-RateLimit-Minute-Remaining") === "0") {
        await sleep(waitMs(res, attempt)); // slow down before the next call
      }
      return res;
    }
    await sleep(waitMs(res, attempt));
  }
  return res;
}

const res = await get("/postnumre/8000");
const postnummer = await res.json();
console.log(postnummer.navn, "| left this minute:", res.headers.get("X-RateLimit-Minute-Remaining"));