How to use SlimCast.

The HEVC encoder is the one hard requirement, and it’s the reason SlimCast works at all: HEVC fits the same picture into roughly half the bitrate H.264 needs, so one modest upload from you becomes full-quality output everywhere. Every Apple Silicon and T2 Mac has one built in, as does any NVIDIA GTX 950 or newer, and AMD and Intel graphics from about 2016 on.

• ✓Your scenes, sources, overlays, filters, transitions and hotkeys — untouched.
• ✓The Start Streaming button you already use. SlimCast intercepts it rather than replacing it.
• ✓Your OBS canvas. SlimCast only ever changes the scaled output resolution, so nothing shifts position.

1. Sign in and open Dashboard›Platforms.
2. Click + Add platform and choose Twitch, YouTube or Kick, then approve the consent screen.
3. Repeat for each platform you stream to. Your stream key is encrypted the moment it’s saved and never shown again.

1. Download the installer for your system from Dashboard›Settings or the onboarding page.
2. Run it, then restart OBS.
3. The SlimCast panel appears with its three tabs. If you don’t see it, open OBS’s Docks menu and tick SlimCast.

1. In the SlimCast dock, click Link account.
2. Your browser opens — approve the request.
3. The dock switches itself to the Home screen. There’s nothing to copy or paste.

Each computer gets its own key, and the dock quietly rotates it about every 60 days so you never hit an expiry mid-stream. If you’d rather paste a key by hand, there’s a fallback field under the button.

The wizard is offered on your first Connect, and lives at gear›Setup wizard afterwards. It’s six screens and the important one is the speed test — SlimCast pushes your real OBS output to a real SlimCast server for about twelve seconds and measures what actually arrives, which is a different and far more useful number than a browser speed test.

If any destination is going out in 9:16, open SlimCrop and build a layout. The SlimCrop chapter covers it in full. If everything you do is landscape, skip this entirely.

A slim bar across the top, always visible. On the left, a coloured dot and one status word: IDLE, CONNECTING…, READY, LIVE, STOPPING… or ERROR. Below it your OBS resolution, frame rate and source bitrate on the left, and your credit balance on the right. On the far right edge, a full-height gear column that opens Settings.

• ✓Click the 1920×1080 · 60 fps · 6.5k ▾ line to open the source popover.
• ✓Click the credits figure to jump straight to Settings›Credits. It turns amber under 0.5 credits and red at zero.
• ✓A red ⚠ beside the status word means OBS’s stream output has drifted off the current SlimCast server — click it for the explanation.

Click the resolution line in the header. Three sections: scaled output (720p / 1080p / 1440p), frame rate (30 or 60), and a source bitrate slider.

• —The source bitrate ceiling is 12,000 kbps — or 20,000 with 2K, and only once your OBS canvas is above 1080p.
• —A resolution larger than your OBS canvas is disabled and marked ⤢ canvas. Raise the canvas in OBS first.
• —4K is locked for everyone. It isn’t supported yet.
• —This changes the scaled output only, never your canvas — nothing in your scenes moves.

A floating window with three rows. It doesn’t block OBS, and it remembers its size and position.

A slim ▴ arrow at the very bottom of the Home screen hides four buttons: Stream Info, SlimChat, SlimCrop and Dashboard. It’s closed on a fresh install, so that arrow is worth knowing about. Its state is remembered.

Connect opens one floating window before SlimCast rents anything. First choose this stream’s destinations—including saved custom RTMP targets—plus landscape, portrait or Dual Format and the 2K output option. The live calculator refreshes after every choice, and the selections from your last stream are already filled in. Continue starts the connection and moves to Stream Info while the servers prepare: category, title, shared tags and YouTube’s description. Metadata autosaves as you type. Apply now pushes it immediately and reports the result per platform.

• —Tags are shared across every platform: maximum 10, 25 characters each, letters and numbers only — no spaces, punctuation or emoji. That’s Twitch’s rulebook applied everywhere so one list writes correctly to all of them.
• —Leave a title blank and it inherits the title from the platform above it.
• —Description is a YouTube-only field.
• —Custom RTMP destinations appear in Stream Setup with their saved names. They have no Stream Info fields because a bare RTMP endpoint has no metadata API.

A two-segment charge bar fills: the left half as your cloud server is allocated, the right half as the transcoder links. The line underneath names the stage. There’s a CANCEL button the whole time.

Use the wait. The pre-flight checklist appears right under the bar — step through your platforms with the ‹ › arrows and fill in titles, categories and tags while the server boots. Under it, a live readout of what this stream will cost per hour, straight from the same biller that charges you.

When the bar completes, it’s replaced in place by a red GO LIVE button. Press it, or press OBS’s own Start Streaming — the dock intercepts it and does the same thing. Because the server is already warm, you’re live in a second or two.

The dock switches to a 60-second rolling signal graph. The dropdown at its top-right picks between SLIMCAST (your cloud server and transcoder) and PLATFORMS (one tab per destination). Under it sits a chip per platform — green ✓ delivering, amber … coming up or reconnecting, red ✕ failed — each showing its real measured delivery rate.

Three things may appear above the main button while you stream:

The struggle advisor never changes anything on its own. It suggests about 75% of your current rate, and either button — apply or dismiss — starts a 15-minute cooldown so it can’t nag.

Press Stop in OBS. A deliberate stop ends the session cleanly and your channels are closed properly. The meter stops with it.

When OBS stops sending, your platforms would normally see the stream end — that clean disconnect is what makes them cut you off, not their own patience. So SlimCast keeps feeding them a holding card instead. Your channels stay live, YouTube holds the same broadcast and the same watch URL, and you come back to the stream you left.

• —The shield holds for 90 seconds. That’s a hard ceiling, matched to the reconnect window.
• —It stands down when you press Stop deliberately — you want a clean ending there, not a card.
• —Kick’s player has been observed stalling at the moment the feed resumes; some Kick viewers may need to refresh.
• —The card is prepared on your cloud GPU, so a first-ever stream at a brand-new resolution may run without it.

There’s nothing to configure. SlimChat watches the main dock: chat connects when your session reaches Ready or Live, and disconnects when you do. You do not have to be broadcasting — being connected is enough.

Everything lands in one scrolling feed, each line prefixed with a coloured platform tag. Four tabs filter it: All, Twitch, Kick, YouTube. Your choice is remembered between OBS restarts. Scroll up to read back and the feed won’t yank you to the bottom; scroll back down and it re-pins to the live tail.

• —Scrollback is capped at 750 lines. There’s no search, no export, and no history across OBS restarts.
• —YouTube chat only exists while a broadcast does — between broadcasts the dock says it’s waiting for one.

1. Click the box reading Message all connected chats….
2. Type, then press Enter or click Send.
3. Your line appears once, tagged [SC] You: — not once per platform.

A counter beside the box measures you against the tightest limit among your connected platforms — YouTube’s 200 characters, versus 500 on Twitch and Kick. Go over and it turns amber and names the platform that won’t take it. Nothing is ever silently truncated: the message goes to every platform it fits, and a line in the feed tells you which one it didn’t. If a platform refuses it outright — followers-only mode, a banned phrase, a duplicate — the reason is printed in the feed too.

Right-click any message in the feed.

• —Only two timeout durations — 10 minutes and 1 hour. There’s no custom duration field.
• —There’s no un-ban or un-timeout in the dock. Undoing one is done on the platform’s own site.
• —Moderation items only appear if that platform’s authorization includes moderation scopes, and never on your own messages.

When anything is moderated — by you here, or by a mod on the platform itself — the affected lines go struck-through and grey rather than vanishing, so you keep the context of what just happened. If a mod clears the whole chat, the feed says so.

Twitch and Kick emotes render as real artwork automatically. On Twitch, SlimChat also matches plain-text emote words against your channel’s and the global 7TV, BetterTTV and FrankerFaceZ sets. Twitch badges render as the real Twitch artwork; Kick roles show as colour-coded diamonds.

The ⚙ gear at the dock’s top-right holds the rest: text size (small, medium, large), timestamps on or off, badge visibility per platform, and a switch for third-party Twitch emotes.

• —Emotes are static images — animated emotes don’t animate.
• —Third-party emote matching is Twitch-only; it never applies to Kick or YouTube.
• —YouTube’s API exposes no image for its custom emojis, so they show as a coloured dot.
• —YouTube messages carry no badges at all today.

The status line reads something like Connected · Twitch 1,204 · Kick 87 · YouTube 12, refreshed about once a minute. These are also what feed the peak-viewer figure and the viewer graph on your dashboard — so if you want that history recorded, keep SlimChat running while you stream. A platform whose count isn’t available shows its bare name rather than freezing a stale number.

You don’t switch vertical layouts by hand. You build named layouts and assign each to one or more OBS scenes — scenes framed the same way can share one. When you change scenes in OBS, the vertical output follows. A scene with no layout falls back to a centred vertical slice, so your vertical feed is never blank, just never what you designed.

The preview is 100% local — it needs no internet, no server and no live stream, and it renders the real OBS program feed, so it shows your transitions and the program side of Studio Mode. Left of it, a collapsible rail lists only the scenes that have a layout, in your own OBS scene order.

• ✓Single-click a scene in the rail to switch OBS to it — this works while you’re live.
• ✓＋ creates a brand-new OBS scene, asks you to name it exactly like OBS’s own Add Scene, then jumps straight into framing.
• ✓－ deletes the selected scene from OBS for real — and registers a proper undo, so Ctrl+Z brings it and its sources back.

• —The rail is a switcher, not your full scene list. A new user sees an empty rail with just a ＋.
• —Selecting a scene switches OBS to it — there’s no select-without-switching.
• —－ refuses your last remaining scene, and refuses any scene used as a source inside other scenes.
• —Both ＋ and － go dead while streaming or recording. Switching scenes stays allowed.

Click ⚙ Layouts at the dock’s top-right to open the Layout Manager, then ＋ for a new one. The wizard is two steps.

The Fill dropdown at the top of step 2 offers four answers to the same question, and they suit genuinely different content.

Fit whole frame is the interesting one: your stream becomes a band across the middle and the space above and below is yours to fill with overlays — a chat capture, a camera, a title card. Rotate has no overlays at all, since a rotated frame already covers the whole screen.

1. Click ＋ Overlay. A magenta box appears on the OBS preview.
2. Drag that box and its corners on the OBS preview to choose what it grabs — any shape you like, no modifier key needed.
3. In the SlimCrop window’s 9:16 preview, drag the overlay to position it, and resize it with the corner handle or the scroll wheel.
4. Optionally tick Border and pick a colour to frame every overlay in this layout.
5. Click Save.

• —Up to 6 overlays per layout, and 24 layouts in total.
• —The main slice can only be dragged on the OBS preview, and only in Crop mode.
• —The editing boxes are temporary — removed on Save or Cancel, force-hidden whenever any output is live, and swept away at the next OBS start if a crash left one behind. They can never reach your audience.
• —Closing the Layout window with its X is a cancel, not a save.
• —The whole wizard is blocked while streaming or recording.

Switching to a scene with a different layout applies in about a second for a crop or reposition change. Changing an overlay’s size, the Fill mode or the border restarts the vertical encode instead — a two to five second blip.

Landscape, up to 8 Mbps, delivered over RTMPS. If your channel is authorized for Twitch’s HEVC tier, SlimCast passes your stream through untouched instead — highest quality per bit, no re-encode, no generation loss.

Your HEVC passes straight through at source quality, so there’s no re-encode at all. SlimCast creates and manages the broadcast for you, and it’s the one platform that can carry landscape and vertical at the same time.

• —Broadcasts SlimCast creates are public. There’s no privacy or test-stream option today.
• —They appear under YouTube Studio’s Manage tab rather than the Stream-now dashboard. Viewers see no difference.

Landscape over RTMPS, up to 8 Mbps. Chat reading needs the one-time browser lookup covered in setup, and metadata only applies once you’re live — see the Stream Info notes above.

TikTok isn’t a one-click connection, and it can’t be: TikTok mints a new stream key for every broadcast and offers no public way to fetch it. That applies to every multistreaming tool, not just this one. So TikTok is reached as a custom destination, and the paste takes about twenty seconds once you know where to look.

1. Start your LIVE in TikTok LIVE Studio or LIVE Center and find the Server URL and Stream Key.
2. In SlimCast, open Dashboard›Platforms and add a custom destination with that URL and key.
3. Set its orientation to portrait so it gets your SlimCrop layout.
4. Connect and go live as normal.

• —Up to 5 custom destinations, and they’re a membership feature.
• —They appear by saved name in the pre-stream setup and calculator. They still have no chat, live status chip or graph tab.
• —Each one costs the same 0.25 credits an hour as any other additional output.
• —There’s no chat for custom destinations, TikTok included.

SlimCast writes only the fields you type into SlimCast, and preserves everything else. Set them in the Stream Info stage after choosing your setup; they’re applied at go-live and re-pushable any time with Apply now. Thumbnails and anything SlimCast doesn’t carry are one click away via the Stream manager ↗ link on each platform’s step.

What OBS sends to SlimCast — one stream, set on the header popover or by the setup wizard. This is the only number that costs you upload, and it never grows with the number of destinations.

Those are measured-upload figures with SlimCast’s headroom reserve already included, which is why they sit above the raw bitrate each resolution uses.

On the cloud side, all your landscape platforms share a single encode, and all your vertical platforms share another. So the bitrate knob is per orientation, not per platform: one Landscape bitrate limit and one Portrait bitrate limit, in gear›Video.

The limit is automatically clamped by the tightest cap among the platforms sharing it, so you can’t set something a member will reject. Passthrough legs — YouTube landscape, eligible Twitch — ignore all of this and carry your source directly.

There’s a ceiling on what SlimCast will accept, because that leg is the one cost that scales with whatever a client decides to send. Push far past it for about twenty seconds and your publish is disconnected — with a dialog naming the exact limit, what you were sending, and what to set instead. Honest 2K streams sit comfortably inside it.

This machine has no hardware HEVC encoder, so SlimCast can’t stream from it. There’s no software fallback. On a desktop PC a supported graphics card fixes it; on older Intel Macs, it can’t be fixed.

That platform’s delivery failed and is retrying on its own — usually a stale stream key or a platform-side problem. Nothing is wrong with your stream, and the others are unaffected. Check that platform’s connection on the dashboard.

After about a minute the dock shows a red row with a countdown, because a stream nobody accepts is usually a stale key and is still costing you credits. Fix the connection on your dashboard; if none recovers, the session ends itself.

The one-time chatroom lookup didn’t complete — nearly always an ad-blocker, VPN or privacy extension. Pause it for slimcast.io and kick.com, open Dashboard›Platforms, and click Retry on the Kick card. Sending and moderation work throughout.

Its token expired or was revoked. Go to Dashboard›Platforms and click Reconnect on that platform.

Three things to check, in order: at least one destination is set to 9:16; the scene you’re on is assigned to a layout (SlimCrop’s label says No layout for “…” if not); and the dock is linked to your account — layouts only save when it is.

A SlimCrop editing marker left behind by a crash. It draws nothing into your stream, and SlimCrop removes any it finds at the next OBS start. You can also just delete it in OBS like any other source.

You sent far more than your tier’s ingest ceiling for a sustained period. The dialog names the limit and what you were sending — set OBS to that or less and reconnect. Repeated kicks lead to a short cooling-off period.