The test list methodology

Censorship findings are only as interesting as the sites and services that you test.

We encourage you to suggest sites and services to test for censorship.

Please read the documentation below to contribute to community resources for censorship measurement research.

What are test lists?

Test lists are machine-readable CSV files that include URLs that are tested for censorship.

Censorship measurement projects like OONI rely on a global community of volunteers who run censorship detection tests from local vantage points. In light of bandwidth constraints, testing most websites available on the internet is not practical (nor possible in many cases). Instead, our measurements focus on a sample of websites provided in “test lists”: machine-readable CSV files with a set of curated, interesting domains. There are two types of test lists:

To maximize the breadth of coverage while reducing research bias, test list URLs are broken down into 30 diverse categories:

These categories range from news media, culture, and human rights issues to more provocative or objectionable categories, like pornography (the latter are included because they are more likely to be blocked, enabling the detection of censorship techniques adopted by ISPs).

Creating test lists requires local knowledge, an understanding of which sites are commonly accessed and more likely to be blocked in light of a country’s social and political environment. The Citizen Lab (which manages the test list project) has, therefore, made the lists publicly available on GitHub, encouraging community contributions.

What aren’t test lists?

1. A list of thousands of sites scraped from Alexa

Creating (or contributing to existing) test lists is not a question of scraping “the top 1,000 sites” from Alexa. Rather, it requires research, an understanding of a country’s social and political environment, and how that may motivate information controls.

2. Blocklists

Some governments occasionally publish official blocklists (or they get leaked) which contain lists of websites that are legally prohibited in a country. Internet Service Providers (ISPs) are then ordered to block access to all websites included in such blocklists, commonly involving hundreds (or thousands) of URLs that contain content illegal in that country (such as gambling, file sharing, adult content, etc.).

Test lists, on the other hand, are not meant to be limited to blocked websites. Rather, they serve the purpose of monitoring when policies change - what’s most likely to be blocked or unblocked. While test lists may include some websites that are known to be blocked (and that is useful for detecting censorship techniques adopted by ISPs), most sites are not censored locally when they are added to test lists. The aim of using the test list methodology is to not only identify censorship, but to also confirm the accessibility of sites. Unlike blocklists (which can include thousands of URLs), each test list is usually limited to up to 1,000 sites (due to the aforementioned bandwidth constraints).

Why contribute to test lists?

1. Censorship findings are only as interesting as the sites you test

When measuring censorship through the use of software like OONI Probe, censorship findings are only as interesting as the sites that are tested. If, for example, is blocked in China, OONI Probe is only likely to detect that if was included in the Chinese test list to begin with.

It’s therefore important to ensure that test lists are representative of many types of online content and reflect the country’s social, economic, and political environment.

2. You can provide local insight

Examining internet censorship in a country requires local knowledge, an understanding of which sites and services are:

To ensure that test lists include a variety of different types of URLs that are updated on an ongoing basis, we encourage community contributions from around the world.

3. Potential risks

When running OONI Probe, you will connect to and download data from the websites included in the global test list and in the test list which is specific to the country that you are running OONI Probe from.

We therefore encourage you to review all of the URLs included in these lists carefully, prior to running OONI Probe, as connecting to some of these websites might be legally questionable (or illegal) in some jurisdictions.

If you are uncertain of the potential implications of connecting to and downloading data from the websites listed in the test lists, you can pass your own test list with the following type of command line option:

ooniprobe <test-name> -f <your-test-list>

Contributing to test lists

You can contribute to test lists in 2 ways:

This requires a bit of research. We provide some recommended research practices for compiling (or contributing to existing) test lists in the following section.

Test list research

Background research

Understanding information controls in a country requires an understanding of the country itself. Some background research on the country in question is therefore essential to identifying websites that are worth testing for censorship.

In-depth PhD style research is not required. In fact, many online resources with country profiles that you can refer to already exist, such as The World Factbook, the OpenNet Initiative, and Freedom House, among others. Your background research probably shouldn’t be limited to such resources. Rather, these resources can serve as a starting point for identifying sites to add to test lists (in which case, you can even refer to a country’s Wikipedia page).

Knowing that a country has many ethnic minorities, for example, is a starting point for subsequently exploring which sites represent the voices of those groups. Due to their sensitive nature, such sites might be more likely to get blocked (now or in the future), and so it might make sense to add them to your test list. By reading news websites from that country, you may come across the names of political activists. Similarly, it may be worth exploring whether those activists have websites and adding them to your test list.

By researching the main economic, political, and social issues of a country, you can search for a variety of different types of sites that address them and present different opinions. Those are the types of sites that are worth adding to test lists to monitor their accessibility over time. The process of identifying sites to add to your test list can also be guided by the 30 categories of the test list methodology.

Drawing inspiration from 30 categories

The Citizen Lab’s test list methodology relies on 30 diverse categories for URLs. These categories serve the following main purposes:

The more diverse the testing sample, the more likely researchers are to identify different forms of internet censorship. By categorizing URLs, researchers can more easily characterize internet censorship depending on what is blocked. In Iran, for example, the breadth and scale of internet censorship appears to be pervasive since many different types of websites were found to be blocked.

When working on a test list, you can refer to the 30 categories and search for local websites that fall under each one. Ideally, a test list includes multiple URLs for each of the 30 categories, though we recognize that this is not always possible.

Research on previous cases of reported censorship

Has censorship been reported in the country that you’re compiling a test list for? If so, which websites were reportedly blocked?

As part of your research for identifying sites to add to a test list, it’s important to explore whether previous censorship events have been reported in the country. Those sites might still be blocked, even if their ban has been lifted. We, for example, found Vimeo and Reddit to be blocked in Indonesia, even though their ban was lifted more than two years ago. Furthermore, certain sites might only be blocked in certain networks, rather than on a nationwide level. By adding sites that have reportedly been blocked to your test list, OONI Probe users can collect network measurement data examining the accessibility of those sites over time (and may even be able to corroborate media reports).

Previous censorship cases can also help with identifying:

To identify censorship cases, you can start off by searching for relevant media articles (where you’re likely to find the most recent cases). In addition to international news websites, it’s important to search for censorship reports through local media outlets as well. You can then refer to a variety of research reports published by a number of digital rights organizations, including (but not limited to) Citizen Lab, Freedom on the Net (Freedom House), OpenNet Initiative, Reporters Without Borders, and ARTICLE 19.

Given that economic, social, and political systems change over time (and the motivations of governments change along with them), it’s important to update test lists on an ongoing basis through the above recommended practices.

Reviewing test lists

All test lists that OONI Probe is designed to test for censorship are hosted in the Citizen Lab’s test-list repository on GitHub.

To review country-specific test lists, please follow the steps below:

Step 1. Find the csv file which is specific to the country that you want to run OONI Probe from (based on that country’s code) here.

If you don’t find a csv file for your country, that’s probably because it doesn’t exist yet. In this case, please refer to the next section on “Creating new test lists”.

Step 2. Add new URLs to the csv file under the “url” column.

Some criteria for adding new URLs can include the following:

For further criteria, please view the URL categories here.

Please try to add URLs which fall under as many (if not all) of these categories as possible.

Step 3. Every time you add a URL, please add the following in the csv file for each new URL:

Step 4. Change the category codes and descriptions for URLs (included under the “category_code” and “category_description” columns of the csv file) only if you think that those URLs have been allocated to wrong category codes and descriptions. In this case, please replace the category codes and descriptions with ones (from the recommended categories that you think are more suitable. We would also appreciate a comment on GitHub or via email explaining the proposed changes.

Step 5. Once you have reviewed a test list based on the above, please submit your changes to us. If you’re a GitHub user, you can do so through a pull request. If you’re not a GitHub user, please send us a spreadsheet (including the same format as github csv files) by dropping us an email at (PGP Key Fingerprint: 4C15 DDA9 96C6 C0CF 48BD 3309 6B29 43F0 0CB1 77B7).

Creating new test lists

If you can’t find a test list specific to your country here, then it probably does not exist yet. Please help us create a test list for your country through the steps below:

Step 1. Create a csv file and name it based on an ISO-3166 two-letter country code which is specific to the country that URLs are being added for. You can find a reference for international standards for country codes here. An example would include a csv file created for Andora, named ad.csv.

Step 2. Include the following columns in the newly created csv file:

Step 3. Add URLs under the “url” column of the csv file.

Some criteria for adding new URLs can include the following:

For further criteria, please view URL categories here.

Step 4. Every time you add a URL, please add the following in the csv file for each new URL:

Step 5. Once you have created a new test list based on the above, please submit your csv file to us. If you’re a GitHub user, you can do so through a pull request. If you’re not a GitHub user, please send us your csv file by dropping us an email at (PGP Key Fingerprint: 4C15 DDA9 96C6 C0CF 48BD 3309 6B29 43F0 0CB1 77B7).

Important tips

  1. Always include the full URL, including the HTTP or HTTPS prefix, exactly as it appears when you type it into a browser. If you include in a test list, OONI Probe won’t be able to test it. Rather, it should be included as, if that is what it looks like in a browser.

  2. Always use the format described in the sections above. The test lists are meant to be machine-readable, and OONI Probe will not parse test lists that don’t strictly follow the prescribed format.

  3. Please use the categories provided here and refrain from adding your own categories. The categories may not be perfect, and we welcome your suggestions for additional/alternative categories. But if you don’t use the prescribed category codes, OONI Probe will not be able to test those URLs, since test lists are meant to be machine-readable.

  4. Please do not scrape and add “the top 1,000 Alexa sites”. Community contributions are more useful when they include URLs that (a) fall under these 30 diverse categories and (b) reflect local insight. Given that many OONI Probe users around the world have bandwidth constraints, we favour quality over quantity in terms of what is tested.

Thanks for contributing!