Synergy + Parsec · Local-first · No cloud

One keyboard and mouse for every computer on your desk.

Glide your cursor across screen edges to control the next machine — keyboard, mouse, clipboard and files follow. And when you need a machine's actual screen, remote-desktop into it and take over in real time. All peer-to-peer over your LAN, on Windows, macOS and Linux.

Download $5/mo · $50/yr
Windows · macOS · Linux
TLS 1.3 peer-to-peer No account required Cross-platform
§ 01 — how it works

Two ways to reach across machines.

input sharing + remote desktop
one app, all local
Input sharing · for screens side by side

Glide across

Push your cursor off the edge of one screen and you're instantly on the next machine. One keyboard and mouse drive them all, arranged on a multi-monitor canvas you drag to match your real desk — and the clipboard and files come with you.

→Best when your machines sit side by side and you want them to feel like one continuous desktop.
Remote desktop · for a machine in another room

Stream in

When you need a machine's actual display — a headless box, a PC in the next room — remote-desktop straight in and view and control its full screen in real time, low-latency, over your LAN. No cursor-crossing required.

→Best when the machine is out of reach or has no monitor and you need its real screen, not just its input.
§ 02 — what's in the box

Everything your desk shares, in one app.

core capabilities first
supporting features below
01

Seamless keyboard & mouse sharing

One keyboard and one mouse drive every computer on your desk. Slide off a screen edge and your input lands on the next machine instantly — no switch, no KVM, no perceptible lag.

02

Multi-monitor canvas layout

Drag each machine's screens onto a real layout canvas to match your desk — zoom, pan, edge-snapping and L-shaped setups. The cursor crosses exactly where your monitors actually meet.

03

Remote desktop — view & control any screen

Need a machine's actual display? Remote-desktop into a headless box or a PC in another room and take over its full screen in real time — its audio comes along, low-latency, peer-to-peer, never leaving your LAN. Beta builds stream with PLV, our own built-from-scratch video codec — pixel-perfect 4:4:4 color with no third-party codec dependencies.

04

Shared clipboard + file transfer

Copy on one machine, paste on another. Send a file to any connected computer, or drag it across the edge and it lands in the folder under the cursor — with a live progress card (speed, ETA, cancel) on both ends. Your clipboard follows you everywhere — and an optional clipboard history keeps recent copies one click away, held in memory only, never written to disk, never shared, and off until you turn it on.

…and more

Controller sharing

Forward a controller to another PC as a virtual Xbox pad, with multi-pad routing.

Pen / tabletbeta

Forward a drawing tablet with full pressure and tilt across the LAN, driver-free.

Works at the lock screen

Keyboard and mouse keep working at the lock and login screen.

Automatic updates

Signed updates roll out and verify in the background. You stay current, hands-off.

Audio passthrough

Hear a connected computer's sound on this one — automatically while you view its screen, or pick it as a source any time. Optionally forward one computer's audio to another, and choose exactly which microphone or input to capture and which speakers to play it on.

Webcam sharingbeta

Share a camera to your other computers and view it from another machine — with an "on air" light on the owner whenever its camera is being watched. Opt-in per device.

Remote Sessions

Save SSH connection profiles and open a full terminal to any server right inside the app — your machines and your remote boxes in one place. Optionally pull your SSH logins straight from 1Password (via the 1Password CLI); Promethean Link stores references only, never your secrets.

Privacy mode

Working on a machine remotely? Blank its physical screens and mute its speakers so nobody at the desk can watch or listen — one toggle, off the moment you're done.

Watch from a browserbeta

Open a shared screen in any browser on your LAN — no install needed on the viewing machine. Handy for a laptop, a spare tablet, or a quick look from anywhere in the house.

Pixel-perfect alignmentbeta

A Calibrate panel plus an on-screen alignment overlay line your monitors up to the pixel — drag the alignment lines right on your monitors, from either machine, until the cursor crosses exactly level. Adjustable line density and thickness, a darkened backdrop so the lines pop, and it's all remembered.

§ 03 — see it in action

30 seconds to get it.

§ 04 — by design

Your desk, your network — and nothing in between.

Promethean Link never routes your input, screens, clipboard or files through anyone else's servers. Machines find each other on your LAN and talk directly, encrypted end to end. The only outbound request is a small license check that carries no user data.

  • LAN-only, peer-to-peerDirect device-to-device connections on your local network. No relay, no middleman hop.
  • TLS 1.3, per-link keysEvery connection is encrypted with its own keys. Pair once; nothing travels in the clear.
  • No cloud, no accountThere's no sign-up and no cloud service to depend on. It works fully offline, on your own wire.
  • You approve every first connectionA new computer must be confirmed with a short pairing code — and you choose per machine: remember it for automatic reconnects, or require a fresh code every time.
§ 05 — platform support

The spec sheet, nothing hidden.

Windows / macOS / Linux · X11
Wayland not yet supported
Capability support by operating system. Full support, partial or beta, planned, or not possible.
capabilityFeature Windowscol 01 macOScol 02 Linuxx11 · col 03
Keyboard & mouse sharing1core ✓ ✓ ◐
Multi-monitor layout canvascore ✓ ✓ ✓
Alignment overlay & pixel calibration15core · calibrate ◐ ◐ ◐
Shared clipboard2core ✓ ✓ ◐
File transfer3core ✓ ◐ ◐
Remote desktop — view another PC11remote ✓ ◐ ◐
Remote desktop — be viewed & controlled4remote ✓ ◐ ◐
Audio passthrough12remote · device pick ✓ ◐ ◐
Webcam sharing13remote · on-air ◐ ◐ ◐
Privacy mode — blank & mute while viewed16remote · privacy ✓ ✓ ◐
Game controller sharing5supporting ✓ ◐ ◐
Gaming keypad detection (Tartarus etc.)6supporting ◐ — ◐
Remote Sessions (SSH + terminal)14supporting ✓ ✓ ✓
Pen / drawing tablet7supporting ◐ — ◐
Works at the lock / login screen8system ✓ ◐ —
Automatic updates9system ✓ — ◐
Display server10system Windows macOS X11 only
✓ Full ◐ Partial / Beta — Planned ✗ Not possible
  • 1Linux now sends & receives with correct key mapping and suppresses local input in edge-crossing mode via an X11 grab (the cursor isn't hidden during capture yet).
  • 2Text and images sync on all three platforms (macOS image sync now shipped). An optional local clipboard history (off by default) keeps recent copies in memory only — never written to disk, never shared to other computers. On Windows and macOS it skips content apps mark as confidential (e.g. password managers); Linux apps don't reliably mark secrets, so be mindful there.
  • 3Transfers work cross-platform on all three — send a file to any computer, and it lands there. Dropping a file onto a computer's tile works on Windows, macOS and Linux; starting a drag out of one machine to another is Windows-only for now (macOS and Linux receive drops but can't yet initiate a drag-out).
  • 4Windows, macOS and Linux can all be viewed & controlled; Linux includes headless hosts. macOS hosting needs macOS 12.3+ with Screen Recording permission. macOS and Linux hosting are newer than Windows and still in beta.
  • 5Linux now shares its own controller and receives a forwarded one — both ways (beta, not yet hardware-verified). macOS can share its own controller to another machine (beta); receiving a forwarded controller on the Mac isn't possible yet (no virtual-pad driver).
  • 6Detected & listed; forwards on the keyboard stream.
  • 7Beta on Windows & Linux (uinput); both still want real-tablet validation.
  • 8Windows: full — keyboard and mouse keep working at the lock and login screen. macOS: a login-window agent can now inject your forwarded keyboard/mouse at the login screen (new, beta) — no screen capture there, and never the FileVault pre-boot unlock, which macOS isolates.
  • 9Linux checks for updates and installs via the .deb (apt) or a portable AppImage; in-app self-replace is Windows-only. macOS updates by downloading the latest .dmg (no in-app self-replace yet).
  • 10Linux is X11 only; Wayland isn't supported yet.
  • 11macOS (VideoToolbox) and Linux (FFmpeg decoder + X11 viewer window) can both view a remote host — newer than Windows and still in beta.
  • 12Hear a connected computer's system sound — automatically while you view its screen, or pick it as a source to keep hearing it without viewing. You can also forward one computer's audio to another, and choose which capture device feeds it and which output device plays it. Windows is full (WASAPI loopback + playback, with input/output device selection); Linux carries it over PulseAudio with device selection (beta); macOS can share its own sound (the system mix or a chosen microphone/input) and play forwarded audio on a chosen output (beta).
  • 13Share a camera to other computers and view it from another machine, with an "on air" indicator on the owner while a camera is being watched. In-app (viewable inside Promethean Link) on all three platforms — new and in beta; showing the shared camera as a virtual webcam inside other apps (Zoom, OBS, Discord) is not shipped yet.
  • 14Saved SSH connection profiles with an in-app terminal, on Windows, macOS and Linux. Optional 1Password integration (beta) fills SSH logins from your vaults via the 1Password CLI where it's installed — Promethean Link keeps references only and never stores your secrets.
  • 15Line monitors up to the pixel: an in-app Calibrate panel with 1 px nudges per computer (all three platforms), plus an on-monitor alignment overlay where you drag the gold edge lines and green helper lines directly on the screens — from either machine — with adjustable line density and thickness and a darkened backdrop. The overlay is new and in beta on all three, and on Linux needs X11 (not Wayland). Calibrated positions persist across restarts.
  • 16While you view a machine remotely, blank its physical displays and mute its speakers so no one at its desk can watch or listen — from the viewer's toolbar, or automatically whenever it's being viewed (Settings). Windows and macOS are full; Linux blanks via DPMS on X11 and mutes via PulseAudio (on Wayland, audio mute only).
§ 06 — pricing

Simple, honest pricing.

All features, up to 5 computers. Subscribe monthly or yearly — or pay once for a lifetime license. No accounts, no cloud.

30-day money-back guarantee — no questions asked

Monthly

$5 /mo

billed monthly

  • Up to 5 computers
  • All features included
  • 30-day money-back guarantee
  • Cancel anytime
Launching soon
Save $10 · 2 months free

Annual

$50 /yr

billed once a year

  • Up to 5 computers
  • All features included
  • 30-day money-back guarantee
  • Cancel anytime
Launching soon

Lifetime

$250 once

pay once, yours forever

  • Up to 5 computers
  • All features included
  • Never expires — no subscription
  • 30-day money-back guarantee
Launching soon

Limited-time offer — the lifetime price may rise or be discontinued at any time. Lock it in while it lasts.

Checkout opens with the public launch — the beta is downloadable today from GitHub below. No free trial — but the 30-day money-back guarantee means zero risk. If it's not for you, we refund you, no questions asked. The lifetime price is offered for a limited time and may change or be withdrawn.

§ 07 — download

Get it running.

Windows is the most complete platform today, with a ready-to-run installer. Linux ships a prebuilt .deb and a portable AppImage (X11, beta). macOS ships a prebuilt .dmg (Apple Silicon or Intel) — it's ad-hoc signed today, so right-click → Open on first launch. macOS and Linux are newer than Windows; expect some rough edges while they catch up. There are two release channels: stable, and a faster-moving beta where the newest features (PLV streaming, the alignment overlay, and more) land first — switch channels any time in Settings → Updates.

Download from GitHub

Windows

Installer · Windows 10 22H2+ · x64

READY

macOS

.dmg · macOS 12+ · Apple Silicon/Intel — beta

BETA

Linux

.deb & AppImage · X11 · x64 — beta

BETA

Minimum requirements

  • Local area network (Ethernet or Wi-Fi) — everything stays on your LAN
  • Windows 10 version 22H2 (build 19045) or later, x64, for the prebuilt installer
  • DirectX 11-capable GPU for remote-desktop decode
  • A Promethean Link license key to activate
  • Linux: a prebuilt .deb (Debian/Ubuntu) or portable AppImage, X11, x64 — beta
  • macOS 12 Monterey or later (Apple Silicon or Intel); the .dmg is ad-hoc signed, so right-click → Open on first launch — beta
§ 08 — questions

Common questions.

General

One keyboard, mouse, clipboard, and screen across every computer on your desk, all on your local network. Glide your cursor off a screen edge to control the next machine (like Synergy), and remote-desktop into any machine when you need its screen (like Parsec) — one app, no cloud, no account.
Up to 5 computers; all features are included for all 5.
No free trial, but every plan has a 30-day money-back guarantee — refund within 30 days, no questions asked.
No. Input, clipboard, files, and the remote-desktop stream stay on your LAN (peer-to-peer, TLS-encrypted). The only outbound request is a small license check carrying no user data.
No. The first time a computer connects you confirm a short pairing code, and you decide per machine: remember it so it reconnects automatically from then on, or require a fresh code every single time it connects. Every link is TLS-encrypted with its own keys either way.
Cross-platform: Windows, macOS, and Linux. Windows is the most complete today; macOS and Linux already do keyboard/mouse sharing, the multi-monitor layout, clipboard, file transfer, remote desktop, audio, webcam sharing and Remote Sessions — they're just newer and still in beta on some of those. See the capability matrix above for exactly what works where.
You get a license key; paste it in Settings. Activation is instant and works offline after the first check.
Yes, from the customer portal; you keep access through the end of your billing period.

Troubleshooting

Turn Discovery on (both machines), ensure they're on the same local network, and allow Promethean Link through the firewall: TCP 24800 and UDP 24801 on the Private network profile.
In the layout canvas, arrange the machines so their screens share an edge, and confirm both are connected. ScrollLock locks the cursor to the current screen — press it again to unlock.
Install/repair the ViGEmBus driver on the receiving PC (reinstalling Promethean Link includes it), and pick the destination in the Controllers panel. The physical controller stays active on the sharing PC.
The viewing PC needs a DirectX 11-capable GPU and the machine being viewed must allow it; reconnect from Connections → View screen.
Grant Promethean Link both Accessibility and Input Monitoring under System Settings → Privacy & Security, then relaunch.
Not yet — today Promethean Link uses X11, so log into an "Xorg"/"X11" session for now. Wayland support is on the roadmap, built on the modern desktop-portal APIs (PipeWire, RemoteDesktop/InputCapture portals, libei) — the same approach Deskflow and GNOME Remote Desktop use. Remote-desktop and being-controlled will come first and work broadly; the cursor-crosses-the-edge input capture depends on your desktop (GNOME and KDE expose the needed portal; some others don't yet).
Recent versions reopen on their own; if an older one didn't, open it once by hand — updates from then on relaunch automatically.