Questions 1 and 2 from you - I am not sure about the number of applications but see the following from 2019 from Companies House on numbers of keys and overall rate limiting:
the 600 calls in 5 mins limit is per API key.
we have a higher limit, that is per IP address.
the document API limit is part of the API key limit.
We allow multiple API keys of course, BUT please be aware of the Fair Use Policy. If we feel you are breaching it, we can and will deny you access to our services, without notice or reason and you will have to contact us to discuss future access.
If we feel you are not handling error codes properly (in particular 429) again, we will deny you acces…
There are also some notes in passing - in the context of the Streaming API - about using multiple keys e.g. this thread:
Hi
I’m trying to determine if, for the streaming API, I need just one key per end point from the list below or can I use the same key to keep a live connection with all six at the same time and keep our db updated?
Company information
Filing history
Insolvency cases
Charges
Officers
Persons with significant control
The documentation makes me think that I do need six.
Connection limits (from Streaming API: )
A maximum of two concurrent connections per-account can be made to the streaming API…
As for your question 3 (this seems to be being asked by a lot of people recently - I’m not sure why this should be? - see for example the following threads:
Hi, I was instructed by email to post my questions here regarding Company House.
Are there any restrictions or legal requirements for a company outside of the UK but in the EU to access company data from Company House through your APIs?
Are we allowed to use this company data to build a product and sell the information without any agreement with the Company House? We are building a Know Your Customer/Business product that will help companies to onboard companies from the UK.
Do we also …
I work on a product which is used by multiple customers and we are looking to integrate with the rest api to access the company house data. We’d like to host the integration with companies house once and then each client would connect to companies house via this central integration i.e.
client 1 → integration → companies house
client 2 → integration → companies house
The impact of this approach would be that all of the requests would come through a single API key (not an API key per client) …
What are the rules regarding commercial use of the API? I assume it’s allowed but I cannot find any terms of use or conditions document about using the API online. There was something on the HMRC Developer Hub but I saw that Companies House is technically separate to HMRC so I don’t know if it applies.
Essentially, if I use this API to generate income as part of a business, what do I need to do? Do I need to register somewhere, or are there some rules that need to be followed.
Thanks
Good luck.