The amount of requests you can do before you run into our rate limit depends on your API key. With our free API key you can make about 10K requests per month. If you need more you can upgrade to the Hobbyist or Pro plan, which you can read more about at our pricing page. Without a key you can still make a very limited amount of requests so you can quickly test if our endpoints fit your needs, or debug a little bit during development. The unauthenticated requests are not guaranteed to work, so we advice you to get a key to not unexpectedly run into the rate limiter.
Read more about the rate limits in the docs.