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Crystal: A Website Downloader

Crystal is a tool that downloads high-fidelity copies of websites for long-term archival.

It works best on traditional websites made of distinct pages using limited JavaScript (such as blogs, wikis, and other static websites) although it can also download more dynamic sites which have infinitely scrolling feeds of content (such as social media sites).

If you are an early adopter and want to get started downloading your first website with Crystal, please see the Tutorial below. Additional documentation will be available once Crystal is no longer in beta.

Download ⬇︎

Either install a binary version of Crystal:

Or install from source, using pipx:

  • Install Python >=3.8,<3.12 and pip:
    • Ubuntu/Kubuntu 22.04+: apt-get update; apt-get install -y python3 python3-pip python3-venv
    • Fedora 37+: yum update -y; yum install -y python3 python3-pip
  • On Linux, install dependencies of wxPython from your package manager:
    • Ubuntu/Kubuntu 22.04+: apt-get install -y libgtk-3-dev
    • Fedora 37+: yum install -y wxGTK-devel gcc gcc-c++ which python3-devel
  • Install pipx
    • python3 -m pip install pipx
  • Install Crystal with pipx
    • pipx install crystal-web
    • ⏳ On Linux the above step will take a long time (10+ minutes) because wxPython, a dependency of Crystal, will need to be built from source, since it does not offer precompiled wheels for Linux.
  • On Linux, install a shortcut to Crystal inside GNOME/KDE applications and on the desktop:
    • crystal --install-to-desktop
  • Run Crystal:
    • crystal

Tutorial ⭐

To download a static website (ex: xkcd):

  • Download Crystal. See the Download section above.
  • Open Crystal and create a new project, call it "xkcd".
  • Click the "New Root URL" button to add the "" URL, named "First Comic".
  • Expand the new "First Comic" node to download the page and display its links.
  • Click the "New Group" button to add a new group named "Comics" with the pattern "". The "#" is a wildcard that matches any number. Make sure it also has "First Comic" selected as the Source.
  • Close the "First Comic" node so that you can see the new "Comics" node.
  • Select the "Comics" node and press the "Download" button. This will download all xkcd comics.
  • Expand the "Comics" node to see a list of all comic pages.
  • Select any comic page you'd like to see and press the "View" button. Your default web browser should open and display the downloaded page.
  • Congratulations! You've downloaded your first website with Crystal!

To download a dynamic website (ex: The Pragmatic Engineer):

  • Open Crystal and create a new project, call it "Pragmatic Engineer".
  • Press the "New Root URL" button and add the URL, named "Home".
  • Select the added "Home" and press the "Download" button. Wait for it to finish downloading.
  • With "Home" still selected, press the "View" button. A web browser should open and display the downloaded home page.
  • While browsing a downloaded site from a web browser, Crystal's server will log information about requests it receives from the web browser. For example:
  • Notice in the server log that many red lines did appear saying "Requested resource not in archive".
    • Since these were fetched immediately when loading the page, they must be a kind of resource that is "embedded" into the page. When Crystal downloads a page it also downloads all embedded resources it can find statically, but these embedded resources must have been fetched dynamically by JavaScript code running on the page, which Crystal cannot see.
  • We want to eliminate those red lines that appear when viewing the home page.

Eliminate red lines:

  • Let's start by eliminating the "Requested resource not in archive" red lines related to URLs like​
  • Press the "New Group" button and add**, named "Substack CDN Asset".
  • Reload the home page in the web browser.
  • Notice in the server log that many green lines did appear saying "*** Dynamically downloading existing resource in group 'Substack CDN Asset':" and that there are no more red lines related to**.
  • All red lines related to** should be gone.

Eliminate the last red lines:

  • There should be only a few red lines left:
    • *** Requested resource not in archive:
    • *** Requested resource not in archive:
    • *** Requested resource not in archive:
    • *** Requested resource not in archive:
    • *** Requested resource not in archive:
    • *** Requested resource not in archive:
  • Eliminate these red lines by creating:
    • a group**, named "Firehose API"
    • a group**, named "Archive API"
    • a root URL, named "Homepage Links"
    • a group**, named "Recommendations API"
    • a root URL, named "Homepage Data"
    • a root URL, named "Service Worker"
  • Reload the home page in the web browser.
  • There should be no red lines left.

Final testing:

  • If you click the "Let me read it first" link at the bottom of the page, a list of article links should appear.
  • Congratulations! You've fully downloaded the page! 🎉

To download a website that requires login (ex: The Pragmatic Engineer):

  • Using a browser like Chrome, login to the website you want to download.
  • Right-click anywhere on the page and choose Inspect to open the Chrome Developer Tools.
  • Switch to the Network pane and enable the Doc filter.
  • Reload the page by pressing the ⟳ button.
  • Select the page's URL in the Network pane.
  • Scroll down to see the "Request Headers" section and look for a "cookie" request header.
  • Copy the value of the "cookie" request header to a text file for safekeeping.
  • Open Crystal, either creating a new project or opening an existing project.
  • Click the "Preferences..." button, paste the cookie value in the text box, and click "OK".
    • This cookie value will be remembered only while the project remains open. If you reopen Crystal again later you'll need to paste the cookie value in again.
  • Now download pages using Crystal as you would normally. The specified cookie header value (which logs you in to the remote server) will be used as you download pages.

History 📖

I wrote Crystal originally in 2011 because other website downloaders I tried didn't work well for me and because I wanted to write a large Python program, as Python was a new language for me at the time.

Every few years I revisit Crystal to add features allowing me to archive more sites that I care about and to streamline the downloading process.

Design 📐

A few unique characteristics of Crystal:

  • The Crystal project file format (*.crystalproj) is suitable for long-term archival:

    • Downloaded pages are stored in their original form as downloaded from the web including all HTTP headers.
    • Metadata is stored in a SQLite database.
  • To download pages automatically, the user must define "groups" of pages with similar URLs (ex: "Blog Posts", "Archive Pages") and specify rules for finding links to members of the group.

    • Once a group has been defined in this way, it is possible for the user to instruct Crystal to simply download the group. This involves finding links to all members of the group (possibly by downloading other groups) and then downloading each member of the group, in parallel.

The design is intended for the future addition of the following features:

  • Intelligently updating the pages in websites that have already been downloaded.
    • This would be done by defining rules on groups that specify how often its members are updated. For example the set of "Archive Pages" on WordPress blogs is expected to change monthly. And the most recently added member of the "Archive Pages" group may change daily, whereas the other members are expected to never change.
    • Multiple revisions per downloaded resource are supported to allow multiple versions of the same resource to be tracked over time.

Contributing ⚒

If you'd like to request a feature, report a bug, or ask a question, please create a new GitHub Issue, with either the type-feature, type-bug, or type-question tag.

If you'd like to help work on coding new features, please see the code contributor workflow. If you'd like to help moderate the community please see the maintainer workflow.

Code Contributors

To run the code locally, run poetry install once in Terminal (Mac) or in Command Prompt (Windows), and poetry run python -m crystal thereafter.

To build new binaries for Mac or Windows, follow the instructions at COMPILING.txt.

To run non-UI tests, run poetry run pytest in Terminal (Mac) or in Command Prompt (Windows).

To run UI tests, run poetry run python -m crystal --test in Terminal (Mac) or in Command Prompt (Windows).

To typecheck, run poetry run mypy in Terminal (Mac) or in Command Prompt (Windows).

Related Projects ⎋

  • webcrystal: An alternative website archiving tool that focuses on making it easy for automated crawlers (rather than for humans) to download websites.

Release Notes ⋮