We record each call made to WebAPI and charge at the end of the month. There is no minimum or maximum limits. More you use, more discount you get.

We have free tier of volume you can use each month.

Pricing table:

calls made, up toprice / 1000 calls
up to 5,000   free 
up to 100,000   € 1.00
up to 1,000,000   € 0.50
up to 10,000,000   € 0.25
all following
€ 0.10

Examples for different usages counting in requests per minute/second or even hundreds of requests per second. 

constant load ofcalls per monthfinal pricediscountdescription
1 call per minute 43,200    € 38.2011.57%moderate usage
10 calls per minute 432,000    € 261.0039.58%normal usage, most customers will not even hit this number
1 call per second 2,592,000    € 943.0063.62%mature brokers might need data very often
10 calls per second 25,920,000    € 4,387.0083.07%heavy constant load all the time, least realistic
100 call per second 259,200,000    € 27,715.0089.31%very heavy load webapi can serve, unbelievable in practice

For example, you want to make ~30000 calls per month. It will costs: (30 - 5(free)) * 1eur = 25 eur

Another example for 1m calls:

Total: 545 eur

Discount: 45.5%