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A web privacy measurement framework
Python JavaScript HTML Shell
Latest commit 372a404 May 31, 2016 @dreisman dreisman Merge pull request #80 from zawarudo/hotfix/readme
Fixed typo

OpenWPM Build Status

OpenWPM is a web privacy measurement framework which makes it easy to collect data for privacy studies on a scale of thousands to millions of site. OpenWPM is built on top of Firefox, with automation provided by Selenium. It includes several hooks for data collection, including a proxy, a Firefox extension, and access to Flash cookies. Check out the instrumentation section below for more details.


OpenWPM has been developed and tested on Ubuntu 14.04. An installation script, is included to install both the system and python dependencies automatically. A few of the python dependencies require specific versions, so you should install the dependencies in a virtual environment if you're installing a shared machine.

It is likely that OpenWPM will also work on Mac OSX, however this has not been tested. If you have experience running OpenWPM on other platforms, please let us know!

Quick Start

Once installed, it's very easy to run a quick test of OpenWPM. Check out for an example. This will the default setting specified in automation/default_manager_params.json and automation/default_browser_params.json, with the exception of the changes specified in

You can test other configurations by changing the values in these two dictionaries. manager_params is meant to specify the platform-wide settings, while browser_params specifies browser-specific settings (and as such defaults to a list of settings, of length equal to the number of browsers you are using. We are currently working on full documentation of these settings.

The wiki provides a more in-depth tutorial, however it is currently out of date. In particular you can find advanced features, and additional commands. You can also take a look at two of our past studies (1) and (2), which use the infrastructure.

(1) The Web Never Forgets (2) Cookies that Give You Away


OpenWPM includes the following instrumentation by default:

  • An HTTP Proxy (mitmproxy)
    • HTTP Requests and Responses
    • Parsing of HTTP Request and Response Cookies
      • NOTE: this will not include cookies set by Javascript, see our Firefox extension option below.
    • De-duplicated content storage
      • Right now we detect and store javascript, but this can be expanded
  • A Firefox Extension
    • Javascript calls
    • Cookie setting and access
  • Disk Scans
    • Flash cookie setting
    • Cookie access

Data Format

OpenWPM saves crawl data in several outputs. The bulk of the data is stored in a SQLite database, but additional data may be stored in locations detailed below.

  • HTTP, Cookie, Javascript calls, and meta-data
    • SQLite database specified by manager_params['database_name'].
    • Schema specified by: automation/schema.sql, instrumentation may specify additional tables necessary for their measurements.
  • Javascript files
    • Collected when browser_params['save_javascript'] = True
    • Javascript files are stored in javascript.ldb. The location of this database is specified by manager_params['data_directory'].
    • The files are stored with zlib compression by the hash of the uncompressed content.
    • The files are stored in a LevelDB database, accessed with plyvel.
    • This hash is used to reference the scripts from the SQLite database, for example the content_hash column of HTTP Responses.
  • Log Files
    • Stored in the directory specified by manager_params['data_directory'].
    • Name specified by manager_params['log_file'].
  • Browser Profile
    • Contains cookies, Flash objects, and so on that are dumped after a crawl is finished
    • Dumped to the location specified in dump_profile command.

The database is keyed by the crawler ID and the top_url being visited (the url typed into the browser address bar).


Note that OpenWPM is under active development, and should be considered experimental software. The repository may contain experimental features that aren't fully tested. We recommend using a tagged release.

Although OpenWPM is actively used by our group for research studies and we regularly use of the data collected, it is still possible there are unknown bugs in the infrastructure. We are in the process of writing comprehensive tests to verify the integrity of all included instrumentation. Prior to using OpenWPM for your own research we encourage you to write tests (and submit pull requests!) for any instrumentation that isn't currently included in our test scripts.


If you use OpenWPM in your research, please cite our current Technical Report on the infrastructure. You can use the following BibTeX.

    author = "Steven Englehardt and Arvind Narayanan",
    title  = "{Online tracking: A 1-million-site measurement and analysis}",
    month = may,
    year   = "2016",
    note = "[Technical Report]"


OpenWPM is licensed under GNU GPLv3. Additional code has been included from FourthParty and Privacy Badger, both of which are licensed GPLv3+.

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