How to multistream with OBS

How multistreaming from OBS works

OBS Studio’s Start Streaming button sends one stream, to the service set in Settings → Stream. A multistream plugin adds more outputs next to it. Each output is its own RTMP connection from your computer to one platform, with its own server URL and stream key.

That is different from a relay service such as Restream, Castr or Streamlabs Multistream, where you upload one stream and their servers copy it to each platform. A plugin costs nothing and keeps your video off anyone else’s server; a relay needs less upload. The Restream pricing guide compares the two.

The two plugins

Multiple RTMP Outputs

A long-running plugin by sorayuki, often called obs-multi-rtmp. It adds a dock where each platform is a target with its own server and key. A target can share OBS’s encoder or use its own. Builds for Windows, macOS (a .pkg installer) and Linux are on its GitHub releases page.

Aitum Multistream

A free plugin from Aitum, the makers of the Aitum Vertical plugin. Its dock lists OBS’s own stream as the “Built-in stream” and lets you add outputs for Twitch, YouTube, TikTok, Kick, Facebook, Trovo, X or any other RTMP service. With Aitum Vertical installed, it also sends outputs from a separate 9:16 canvas. It runs on Windows, macOS and Linux and is listed on the OBS forum.

Match the plugin to your OBS version

OBS plugins are built against a particular OBS version. The author of Multiple RTMP Outputs asks you to match them, and names the OBS version in each release title. When they don’t match, OBS may refuse to load the plugin or ask you to update or remove it at start-up.

On 1 November 2026, the newest Multiple RTMP Outputs build (0.7.4.5) names OBS 32.2.1, while OBS itself is at 33.0.1 (released 29 October 2026). Aitum Multistream’s forum page lists OBS 30.0.0 as its minimum. Before you update OBS, check that your plugin has a release for the new version, and download plugins only from GitHub or the OBS forum.

Set up Aitum Multistream

1. Quit OBS. Download the installer for your system from the plugin’s OBS forum page or its GitHub releases, and run it.
2. Open OBS and set your main platform as usual in Settings → Stream. This becomes the Built-in stream.
3. Open the Aitum Multistream dock. If you don’t see it, look in the Docks menu.
4. Click the gear icon in the dock, open the main outputs and choose Add Output. Pick a service, or Other Service for anything not listed, then enter a name, the server and the stream key.
5. Leave the video encoder on Main Encoder to share OBS’s encode, or pick another encoder in the output’s advanced settings to give that platform its own resolution, bitrate and frame rate.
6. Start OBS’s own stream first, then start each extra output from the dock.
7. Run a test on a private or unlisted stream where the platform offers one, and watch for dropped frames before you go public.

Set up Multiple RTMP Outputs

1. Quit OBS. From the GitHub releases page, download the build that names your OBS version and install it. On Windows, the author asks you not to change the install folder.
2. Open OBS. The plugin adds its own dock; if it isn’t visible, look in the Docks menu.
3. Add a new target for each extra platform, with its server URL and stream key.
4. For each target, choose whether to share OBS’s encoder or use a separate one with its own settings.
5. Start each target from the dock, or turn on its option to start and stop together with OBS’s own stream.

Shared or separate encoders

Shared. The picture is encoded once and the same data goes to every platform. It costs about as much processor or graphics time as one stream. Every platform then gets the same resolution, frame rate and bitrate, so those settings have to suit the strictest platform. Twitch’s broadcasting guidelines, for example, give 6,000 kb/s for 1080p at 60 fps, so YouTube gets 6,000 kb/s too, the minimum YouTube lists for 1080p60.

Separate. Each platform gets its own encode, so YouTube can have 12,000 kb/s while Twitch stays at 6,000. Every extra encode costs more processor or graphics time, and more upload. Use a hardware encoder where you can: on a Mac, OBS offers Apple VT H264 Hardware Encoder.

Shape. A shared encode can’t change shape. A 16:9 picture sent to TikTok arrives with black bars above and below, and Instagram crops its sides. For a real 9:16 version you need a second canvas, such as the free Aitum Vertical plugin, which is a second encode and a second upload.

Upload bandwidth: the maths

With a plugin, every platform is a separate upload from your computer. Add up the video and audio bitrate of every stream, then leave headroom: plan to use no more than about two thirds of the upload speed a speed test shows, which is the total times 1.5. Upload speed varies through the day, and when it dips below what you send, OBS drops frames on every output that shares that connection.

Test from the computer you stream on, over a cable if you can. If the numbers don’t fit, lower the bitrate on every output, drop a platform, or use a relay so you upload only once.

Twitch’s simulcasting rules

Twitch has allowed simulcasting to any live streaming service since October 2023. Its terms of service set three conditions, which it calls the Simulcast Guidelines:

• the quality of Twitch viewers’ experience must be no less than on the other platforms, including how you engage with Twitch chat;
• you may not post links to, or otherwise send your Twitch community to, your simulcast on other services;
• you may not use third-party services that combine activity from other platforms on your Twitch stream, such as merged chat.

In practice: if YouTube gets 1080p60, Twitch should too, and don’t say “come over to YouTube” on stream. On 25 February 2026 Twitch’s CEO said on Twitch’s Patch Notes stream that combined chat would be allowed, as long as streamers deal with rule-breaking messages from the other platforms. The written terms still contained the condition in October 2026, so check them before you show a combined chat on screen. Streamers with an exclusivity agreement with Twitch can’t simulcast at all.

When a native app is simpler

OBS with a plugin is free and very flexible. The cost is upkeep: a plugin release to match each OBS update, a second plugin for a vertical canvas, and encoder settings to work out for each platform. If that is more than you want to look after, a relay service or a dedicated multistreaming app does the same job with less setup.

On a Mac with Apple silicon and macOS 26 or later, Mucast, the app this site is for, multistreams without plugins. It encodes the show once, in hardware, and gives each platform its own connection, so one slow platform doesn’t hold up the rest. Like OBS with a plugin it uploads one stream per platform, about 6 Mb/s each in landscape and about 4 Mb/s each in portrait, and there is no relay. Each show streams in one shape, landscape or portrait, so you can’t send a 16:9 and a 9:16 version at the same time as you can with OBS and Aitum Vertical. The free version streams to 2 platforms at once, up to 1080p at 30 fps, without a watermark; Pro costs $19.99 a month, $180 a year (with a 7-day trial) or $399 once.

OBS stays the better choice on Windows or Linux, on Intel Macs, when you need both shapes at once, or when your show depends on OBS plugins and scripts.

Download Mucast for Mac