Cross-check an address against its postal code
Catch a mismatched street address and postal code before an order ships, by resolving each independently and comparing what they actually reveal.
Monitor your key's usage before you hit a limit
Finding out you are near your daily limit because a request just got rejected is the least useful way to find out. Every response already carries the numbers needed to see it coming.
The headers to watch
X-Quota-Limit: 2500
X-Quota-Used: 2210
X-Quota-Free-Remaining: 290
X-Quota-Network-Used: 2210
X-Credits-Remaining: 5.75
X-Key-IPs-Used: 2
X-Key-IPs-Limit: 3
X-Quota-Reset: 2026-09-22T00:00:00ZX-Quota-Free-Remaining shrinking toward zero is your clearest early signal for the free daily allowance. X-Credits-Remaining tells you how much runway is left once you have moved past the free allowance and are drawing on prepaid credit at €0.0001 a request.
Setting your own alert threshold
Rather than waiting for a 429, log or alert once X-Quota-Free-Remaining drops below a threshold you choose, such as 10 percent of X-Quota-Limit, so there is time to react, whether that means slowing down a batch job, topping up credit, or simply expecting a quiet period until X-Quota-Reset.
Watching key IP slots too
X-Key-IPs-Used and X-Key-IPs-Limit track how many different source addresses have used a given key under its rolling IP slot allowance. A key suddenly used from more addresses than expected, climbing toward its limit, is worth investigating on its own, separate from request volume, since it can point to a key being shared more widely than intended.
Building a simple dashboard
A small script that logs these headers on a sample of requests, or on every request if volume is low enough, gives you a usage trend over time without needing a separate monitoring call, since the numbers arrive on responses you were already making. Plotting X-Quota-Used against time across a day or a week shows usage patterns that a single snapshot never would.
Acting before you hit the wall
Once you see a consistent pattern of running close to your limit, the two paths forward are the same two options available at any point: add prepaid credit for occasional overflow, or move to an Unlimited key at €50 a month if you are consistently past the free allowance. Either decision is easier to make calmly, ahead of time, than in response to a live 429 blocking real traffic.
Reading quota headers as routine telemetry, not just as something to check when a request fails, turns a hard limit into a manageable trend. Current allowance and credit options are on the pricing page, and full header definitions are on the rate limits docs.