Free, no-hassle watch parties on every streaming platform.

Not suitable for use. This project is under current development and is not yet fully functional.

If you use Firefox, you can install the add-on from the Firefox Add-ons site. This is the easiest way.

Alternatively, you can download the latest ZIP file from GitHub Releases. To install from GitHub Releases, you either need to install the add-on temporarily via about:debugging, or switch to Firefox Developer Edition so you can install it permanently. If installing from GitHub Releases, you will need to update manually.

If you use Chrome, you can install the extension from the Chrome Web Store. However, using Chrome is not recommended, because not all functionality is available (see below).

Alternatively, you can download the latest ZIP file from GitHub Releases. To install from GitHub Releases, download the latest ZIP file from GitHub Releases and install it by going to chrome://extensions, enabling developer mode (upper right corner), and loading the ZIP file as an unpacked extension. If installing from GitHub Releases, you will need to update manually.

In Chrome, Hypercast also in a degraded mode that does not support certain streaming sites, and cannot be customized to fix issues that come up. This is because Google recently removed support for extensions that allow users to customize website behavior, including most ad blockers (not surprising, since Google is an ad company and makes most of its money by selling access to your personal data). Already-published extensions are still runnable for now, but they will all be deleted by Google in mid-2023, and it is already impossible to publish new ones. Numerous complaints have been registered since 2019 by many community members, but Google has ignored all of them. As a result, you should expect an inferior experience and more bugs when using Chrome. Unfortunately, there is no way to resolve this issue since it is Google which has made the decision to remove this functionality, against our wishes, and they made sure to leave no available workarounds. May we suggest Firefox instead?

However, if you cannot switch to a less user-hostile browser, you can still use Hypercast on a subset of streaming sites.

Once you have the extension installed, go to the settings (on Firefox, this is accessed by selecting the add-on from the list of installed add-ons; on Chrome, this is accessed by right-clicking the extension icon in the toolbar). You and everyone you want to watch together with must enter the same "session ID". This can be any text; it is like a shared password. Click Save. The other settings can be left at their defaults.

Once you have your session ID set, go to any streaming site and open a TV show, movie, or other video. Click the extension icon in the browser toolbar. When you do so, your video will be automatically synchronized with anyone else who is already watching. If you refresh the page or leave and come back, you have to click the extension icon again to re-sync.

When you are synced, your play/pause/rewind/fast-forward operations are automatically applied to everyone else's video as well, and theirs are applied on your end. Everyone has control of the video.

For some sites, Hypercast isn't able to automatically detect the video element to sync, so you won't be synced immediately upon clicking the extension icon. In this case, it falls back to waiting until the video is playing, and then it assumes that whichever video is playing is the one it should sync.

Hypercast does not stream any video; rather, it just synchronizes the playback of everyone in the session. As such, everyone needs to have access to the video you want to watch, and you need to make sure everyone is actually watching the same video (e.g., by sending them the link using an instant messaging program).

Note that if anyone in the session is using Hypercast version 0.0.9 or later, then everyone else has to as well. The same is true of version 0.0.7; these two versions contain breaking changes.

If you have issues, check the JavaScript console and filter for Hypercast. I tried to include verbose logs so that it is clear where things go wrong if they fail.

You can easily run your own instance of Hypercast if you want. This is nice because you know for sure that it will never change or go away, and you retain full ownership over your data.

You probably don't need to run your own instance if you are just concerned about privacy, because all messages routed through Hypercast are end-to-end encrypted using the session ID that you configure in the browser extension settings; since version 0.0.7 this ID is never sent to the server without first being SHA-256 hashed.

Instructions for Railway (free):

• Create a new app and service on Railway. If you want, add a custom domain. Otherwise you can use the default https://somename.up.railway.app.
• Checkout the repository and run railway link in the server subdirectory; link to the newly created service.
• Run railway up to deploy.
• If you want a private instance (only your friends can use it), run railway variables set AUTH_TOKEN=whateveryouwant.
• Your friends will need to put https://somename.up.railway.app (or your custom domain) under Hypercast instance in their extension settings. If you set AUTH_TOKEN then they'll also need to fill in the value under Access token.

Instructions for Heroku ($7/month):

• Create a new app. If you want, add a custom domain. Otherwise you can use the default https://somename.herokuapp.com.
• Install Docker (needed because Heroku doesn't support building Docker images automatically).
• Checkout the repository and run heroku git:remote -a somename in the server subdirectory.
• Run heroku container:push web and heroku container:release web to deploy.
• If you want a private instance (only your friends can use it), run heroku config:set AUTH_TOKEN=whateveryouwant.
• Your friends will need to put https://somename.herokuapp.com (or your custom domain) under Hypercast instance in their extension settings. If you set AUTH_TOKEN then they'll also need to fill in the value under Access token.

Instructions for other platforms:

• Install Docker.
• Checkout the repository and run docker build . -t hypercast.
• Push the image to some Docker registry.
• Arrange for the image to be run on your server. Set $PORT to some value for the container and map that to localhost port 80 on your server.
• Obtain a certificate for your preferred hostname and configure renewals.
• Set up a reverse proxy or load balancer to terminate TLS and forward traffic to the container.

If you want to skip over building your own image then you can use the release versions that I publish to Docker Hub instead (link). For Railway or Heroku you can use a Dockerfile that just contains a FROM line naming the Docker Hub image.

You can also run the server on bare metal if you are a minimalist. It is just a simple Node.js app with no external dependencies.

The only data that is sent to the Hypercast server is play/pause events and seek timestamps from each client. Furthermore, all data is end-to-end encrypted and authenticated using AES-GCM as implemented by Forge, so it is impossible for the server operator to reconstruct any information about any client that connects to it, other than how often it communicates with other clients.

There is no option to have a user account with Hypercast, and no database which could store personal information even if such information were collected.

These claims can be easily validated by inspecting the source code, which aims to be simple and transparent.

If you have a privacy concern, please email privacy+hypercast@radian.codes and I will do my best to get back to you as soon as possible.

Hypercast is implemented as a browser extension that has permission to execute JavaScript in the context of streaming websites. This means that if the extension were compromised by an attacker, your credentials to those sites could be stolen. This is a fairly serious risk so the extension is written to be as secure as possible. This is accomplished in a few ways:

• The extension only requests permissions for the most popular streaming websites by default. (Coming soon:) You can temporarily turn it on for other websites, or you can download an alternative version of the extension that has more websites enabled by default if you prefer.
• The server is not trusted; even if an attacker fully controls the server, it is impossible for them to read any data sent by the extension, or send any data to the extension from their end. The most that they can do is execute replay attacks to cause actions from other users to be repeated unexpectedly.
• The code for the client is as simple as possible in order to limit the possible attack surface.
• I try to exercise good security hygiene for managing both personal and business infrastructure, such as using unique high-entropy passwords and TOTP-based two-factor authentication on all accounts, limiting OAuth and access token scopes, and periodically revoking unneeded permissions and third-party integrations.

If you find a security issue, please email security+hypercast@radian.codes and I will do my best to get back to you as soon as possible.

Hypercast is directly inspired by TwoSeven. I experienced bugs with some streaming services on TwoSeven, and I was not able to fix them since the software is not open-source. Thinking it over, I figured it should take very little time to write a replacement, so I created Hypercast. I made some architectural choices which should make it very unlikely that Hypercast will break on individual streaming platforms due to changes on their end, and to simplify the user interface by not embedding the video within a custom website.

Despite the inspiration, I am not affiliated in any way with TwoSeven and have no knowledge of its design or implementation besides what was apparent by looking at the user interface and behavior.