What is over-blocking?

Over-blocking is when a web filter blocks sites a school has a reason to keep open, such as education, health, government or news sites, because they also carry a category the filter blocks.

Does CIPA require schools to block gambling, weapons or social media?

No. CIPA names three kinds of content: obscene images, child sexual abuse material and, for minors, material harmful to minors, which the law defines in terms of sexual content. Every other category is a local choice written into the district's Internet Safety Policy.

Where do the numbers come from?

From exact counts over 103,367,510 categorised domains (October 2026). For each combination of categories you choose, the audit adds up how many domains your settings would block and how many of them also carry an education, health, government, news, science or civic label.

Free tool for districts and libraries

Is your web filter blocking more than CIPA asks?

Tick the categories your filter blocks. In a few seconds you get a report on how much of the web that removes, how many education, health and government sites go with it, which settings cause the damage, and whether the sites your teachers rely on are affected.

Based on exact counts over 103 million categorised domains. No login, nothing is stored.

Which categories does your filter block?

Start from:

Optional: sites your staff and students rely on

We check each site's categories against your settings and show which would be blocked and why. Only the site names are sent; nothing is saved.

How to read the report

What CIPA actually requires

The Children's Internet Protection Act names three kinds of content: obscene images, child sexual abuse material and, for minors, material harmful to minors, a standard defined in terms of sexual content. In category terms that is adult content, and in practice you also need to stop proxy and VPN sites, or students simply route around the filter. Everything else is a choice your board makes in its Internet Safety Policy.

Why blocking one category can close an educational site

Many sites carry more than one category. A school athletics page is Sports & Recreation and Education. A town portal is a Community site and Government. Most filters block a site as soon as one of its categories is blocked, so a category aimed at distractions can take civic and educational sites with it. The report counts exactly those sites.

What "protected sites" means

Sites that carry an education, health, government and legal, news, science, e-learning, religion or political label: 16.3 million domains in our data. A blocked site with one of those labels is not necessarily wrong to block, but each one is worth a second look.

What to do with high-cost categories

Categories that remove many protected sites are usually better handled with time schedules (for example only during lessons), stricter rules only for younger grades, or an allow list for the sites you know you need, than with a blanket block.