API Rate Limits, Quotas, and Usage Tiers

import hashlib, json, time
import redis

cache = redis.Redis(host="localhost", port=6379, db=0)
CACHE_TTL = 3600  # seconds (1 hour)

def cached_search(params: dict) -> dict:
    cache_key = hashlib.sha256(json.dumps(params, sort_keys=True).encode()).hexdigest()
    cached = cache.get(cache_key)
    if cached:
        return json.loads(cached)

    import requests
    response = requests.get(
        "https://www.googleapis.com/customsearch/v1",
        params=params
    )
    response.raise_for_status()
    result = response.json()
    cache.setex(cache_key, CACHE_TTL, json.dumps(result))
    return result

# If you only show 3 results, don't over-fetch
GET https://www.googleapis.com/customsearch/v1?key=YOUR_KEY&cx=YOUR_CX&q=best+espresso&num=3

# Page 1 — fetch on search submit
GET ...&q=pasta+recipes&start=1

# Page 2 — fetch only when user requests it
GET ...&q=pasta+recipes&start=11

import asyncio

_pending: dict = {}

async def coalesced_search(params: dict) -> dict:
    key = json.dumps(params, sort_keys=True)
    if key in _pending:
        return await _pending[key]  # reuse in-flight request
    future = asyncio.ensure_future(_do_search(params))
    _pending[key] = future
    try:
        return await future
    finally:
        _pending.pop(key, None)

# Instead of fetching all results and filtering to PDFs in code:
GET https://www.googleapis.com/customsearch/v1
  ?key=YOUR_KEY
  &cx=YOUR_CX
  &q=annual+report
  &fileType=pdf
  &siteSearch=sec.gov
  &siteSearchFilter=i

async function searchWithBackoff(params, maxRetries = 4) {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    const res = await fetch(
      "https://www.googleapis.com/customsearch/v1?" + new URLSearchParams(params)
    );
    if (res.ok) return res.json();
    if (res.status === 429 || res.status === 500) {
      const delay = Math.pow(2, attempt) * 1000 + Math.random() * 500;
      await new Promise(r => setTimeout(r, delay));
      continue;
    }
    throw new Error(`API error: ${res.status}`);
  }
  throw new Error("Max retries exceeded");
}