Emma is a lightweight censorship analyser that tests if the machine it's running on can use the Tor network. Emma does so by testing if it can

Risk Assessment

Hidden content

Accessbility is determined by including IFrames of the browser representation of the directory authorities and relays. The IFrames are not visible to you but are loaded in the background. The procedure is similar for determining the accessbility of websites. Hereby an image of the external page is loaded into a <img> tag. These images are also hidden.

Data we collect

We collect information about whether you can establish connections from your location to certain Tor network directory authorities and relays, as well as commonly known sites with potential inaccessibility in restrictive countries.

Date and time of measurements

We collect the time and date when you run the measurements. This data helps us evaluate when measurements were taken and compare measurements over time.

Country code

In order to assign the measurements to an exact location, geolocation is used based on your IP address. When starting the measurements, your country code is determined and recorded. If you share the test's results with us, your country code will be attached.

Sharing your results

After performing the measurement test, you will be given the option to save the results locally. This file also contains the country code and a timestamp. Since we are also very interested in learning where Tor is blocked, we ask you to share this file with us. By doing so, you will be sharing your country code and the result of the test. If you wish to contribute to the Tor Project, please send the result (the file emma.csv) to the following email address: frontdesk@torproject.org

This test is not definitive proof that Tor is blocked in your country. There are other elements to look at, but it is an indication that you may need to use a Tor bridge to circumvent censorship.

Browser Instructions

Use Google Chrome, Mozilla Firefox, or Apple Safari to perform the measurements. Do not use the Tor Browser or Brave, as the connection tests with these browsers do not reflect the actual circumstances. Other browsers may also exhibit any misbehavior in this regard.

Please note that the measurements are partly based on HTTP. Directory authorities and relays are only accessible via pure HTTP in their browser representation and do not offer reachability via HTTPS. For this reason, disable all extensions that force a redirection to HTTPS. In the case of using Mozilla Firefox, please make sure that the security setting in Privacy & Security -> HTTPS-Only Mode is set to Don't enable HTTPS-Only Mode.

Important: before you start the measurements, please disable your VPN service (if applicable) to avoid interfering in the test and changing your location. Furthermore, please empty your browser cache before each restart. In case of a page already loaded into the cache, the results will be wrong.

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