A transparency campaign from

About Blocked

The Blocked project aims to improve transparency about filters that are provided by mobile phone companies and Internet Service Providers (ISPs). Central to this is the Blocked tool, which allows anyone to find out if a website is being blocked by filters. This tool allows us to correct errors and better understand the limitations and impact of filters.

You can read more about Blocked and ISP filters in: TechdirtBig IssueSTV, The GuardianThe Independent and Forbes.

There is also more information in the FAQs section of this site and a general statistical analysis of our results here.

If you are a staff member at an ISP who has received a notification and want to understand what it is, how they are generated and sent, or how to respond to them, please see our ISP page.

Why are websites being filtered?

Mobile phone and Internet Service Providers (ISPs) provide filters that aim to stop children from seeing harmful content. Some companies give their customers the option to opt in to activating filters. Others switch them on by default.

Because they rely on automated searches for certain words and images, filters overblock many websites that are not harmful to children. This has included websites aimed at young people - for example,  sites offering advice on alcohol, drugs and sex. 



What are ORG's concerns?

ORG is concerned that filters are blocking large numbers of websites to UK households. This has implications for individuals, charities and businesses. There are also concerns around children and young people's right to access information.

We think that there is a lack of awareness about the mistakes that filters make. Many website owners who have contacted us were shocked to find out that their site is blocked. 

Filters are a blunt tehnical tool for challenging a social problem and there is no evidence that they work. We believe that the emphasis for keeping children safe online should be through education and parental supervision. 

What does ORG want to happen?

We want filters to be opt-in and not switched on by default. Currently, Sky and the main mobile phone providers switch on filters automatically for their customers. We think customers should be given a choice about this upfront.

We want more transparency about how ISPs decide what to filter and the companies they use to do this for them. 

We want more awareness of filters to help website owners check and challenge blocks.

We want to make it easier to get sites unblocked. We think one of the ways that mobile phone companies, ISPs and their safety project Internet Matters can do this is by promoting the Blocked tool, which is the only way that someone can instantly and simply check if a website is blocked.

Court injunctions for blocks

Courts in the UK issue injunctions for website blocking. While it is public knowledge what services are being blocked, the applicants are gennerally granted the power to vary the domains or IP addresses associated with the service without reference to the court, and without publicising what exactly is being blocked.

The result is that it is not possible to verify whether the blocking is applied appropriately.

Our testing

We have attempted to compile a list of potentially affected domains that have been in use by infringing sites from publicly available sources. We test this list to see if they are blocked. For those sites that are blocked, we classifiled the observable behaviour of those sites in April-June 2018. We found that 37% of the blocks were in error.

Also, the block lists between each ISP is different. This should not be the case. For instance, while found errors in nearly 400 domain blocks, most ISPs are only block around 250 of these, and BT is blocking only 100 of these domains. 

Errors in injunction blocks

The error page shows which domains are blocked by which ISPs in our view incorrectly. We have classified the kinds of errors:

Domain currently broken This means the domain does not function, for instance returning an error message such as 404 or "cannot connect to database
Domain does not resolve This means that DNS no longer returns a result, so the domain cannot be found
Domain for sale or parked This means the site has a message saying the site domain is “parked” (out of use) or for sale
Domain inactive This means the domain gives a message that is it inactive, or returns a blank page
Domain may be abusive This means that the activity on the website is abusive, such as attempting to deliver malware or engaging in "click fraud" such as redirecting through advertisements
No court order identifiable This means that we could not identify a court order that would cover the site, although it could be subject to an order
Site in legitimate use This means the site is clearly being used to publish legitimate material

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