We are already into the middle of July and the nights are starting to draw in. That time of the week has again arrived for us to talk about the API ratings over the past seven days. We launched API.expert earlier in the year as a simple way to provide everybody with insights into the API economy and the leading APIs in different categories in particular. The basic service is free and will remain free, but other, related services will be built on top of it, including your very own API.expert dashboards if you want them! 

If something is missing from our API Ratings that you think should be here, don’t hesitate to drop us a line! 

Now, onto what the past week tells us about the state of the world of APIs as we plunge into the second half of July 2020 

API Performance Headlines 

We look at over 200 APIs, but pull all the metrics together to give you a general feeling for the service quality for an organization’s APIs in a particular category.  

We do see that certain providers consistently vie for top spot in their category including GitHub and Google with others doing less well such as Halifax and the NHS. 

Top Performing API Ratings based on overall quality in each category were: 

API Ratings Week Ending 13 July 2020 


CASC score 

Corporate Infrastructure 

GitHub 9.64 
Covid-19 NovelCOVID (lmao.ninja) 9.24 

Cryptocurrency Exchanges  


PSD2 Banks 

Nordea Bank 9.91 


Google 9.60 

Social Networks     

Twitter 9.67 

UK Open Banking (Open Data)  

Bank of Ireland   9.74 

UK Government

Police.UK 9.24 

US Government  

Department of Justice 9.74 

A slightly less volatile week for our API Ratings with GitHub replacing Pivotal Tracker in Corporate Infrastructure, Twitter Google in Social Networks, Police.UK GOV.UK in UK Government and Bureau of Labor Statistics Department of Justice in US Government.

GOV.UK in UK Government plunges into the Red Zone and Nordea Bank reclaims the crown for the private sector with a near-perfect CASC score of 9.91. A CASC score of over 9.00 is very good and one of 9.50 or more exceptional. Six of the nine categories are headed by organization with a CASC score of 9.50 or more this week. Sustaining a CASC score of >9.25 over a period of several weeks is a good showing and congratulations to those organizations that achieved it.

Top Performing API Ratings based on latency in each category were: 

API Ratings Week Ending 13 July 2020 


Category  Organization

Median latency 

Corporate Infrastructure 

Microsoft Office227 ms
Covid-19 CDC tools (Centers for Disease Control and Prevention) 156 ms 

Cryptocurrency Exchanges     

FTX 207 ms 

PSD2 Banks 

Nordea Bank 174 ms 


Facebook 290 ms 

Social Networks      

Google 57 ms 

UK Open Banking (Open Data)     

HSBC 82 ms 

UK Government    

Police.UK 90 ms 

US Government    

Department of Justice 72 ms 

Yet another stable week this week with no changes again to the top performers. Google takes the overall title again with a median latency of 5ms in Social Networks. An important caveat: medians can be misleading! An API might have a fast median latency but produce many slow outliers. These won’t affect the median, but they mean that users can experience many calls that were unacceptably slow. So just being fast isn’t everything. You have to be reliable too if you want to have good APIs and get a high CASC score! As so often, FTX tops the Cryptocurrency Exchange category, but this week are thirteenth out of 18 overall with a CASC score of 8.27still placing them in the Green Zone. But it is still worth remembering that it’s no good just being fast if you are flakey, although being fast does help! 

Wooden Spoon – worst quality across all categories 

API Ratings Week Ending 13 July 2020 


Category Organization CASC score 
Corporate Infrastructure Nobody below 8.00!  
Covid-19 Coronavirus COVID19 API (covid19.api.com) 7.22 
Cryptocurrency Exchanges RadarRelay 6.93 
PSD2 Banks Open Bank Project 6.69 
Search Foursquare 7.56 
Social Networks Nobody below 8.00!  
UK Government GOV.UK 5.25 
UK Open Banking (Open Data) Nobody below 8.00! (But see below)  
US Government Department of Commerce 4.74 

A few changes this week with nobody below 8.00 in Corporate InfrastructureCoronavirus COVID19 API (covid19.api.com) replacing Coronavirus Data API (thevirustracker.com) in Covid-19, Open Bank Project a new entry in PSD2 Banksnobody in Social Networks, nobody in UK OPen Banking (Open Data), GOV.UK replacing NHS in UK Government, Department of Commerce a new entry in US Government. 

Nationwide Building Society Halifax actually had a CASC score of 4.38, but this was caused by Nationwide moving the URL of an endpoint, so he have given them a mulligan. Which means that the Department of Commerce in US Government claims the Wooden Spoon this week. 

Something of interest 

GOV.UK was top of the world in our API Ratings last week as overall champion with a near-perfect CASC score of 9.88, but has plummeted to the ground this, into the Red Zone with a CASC score of just 5.25. What went so wrong? 

All of the UK Government APIs have a 100% pass rate, so much respect for that! GOV.UK is the second fastest, but it has a high percentage of outliers. GOV.UK may always return, but it is not reliable in how quickly it does that, both in terms of standard deviation of the latency and in the number of exceptionally slow responses (outliers). Slow and unreliable responses degrade user experience of an API, which is why they lead to a greatly lowered CASC score.

We can see that Azure and IBM Cloud are quite a lot slower than AWS. This will partly explain the increased standard deviation of latency and thus lower CASC score. It is only through actively monitoring your APIs that you can pick up the variations in their performance and quality that can occur over time periods of a few days. GOV.UK has gone from hero to zero in one week and needs some attention to get it back to where it should be – and was last week!  

See you again in a week as we look once more at the State of the APIs as we plunge ever deeper into July!

And remember if there is an API Rating missing, or if you want your own, just contact us.