Best open-source clipboard sync between Mac, Windows and Linux

Most people who search for this don't actually want a list of every clipboard tool that exists. They want a tool that:

• works on macOS, Windows, and Linux — all three, as first-class citizens;
• is open source, so the privacy claim can be checked, not just trusted;
• doesn't force a cloud account (Apple ID, Google account, vendor login);
• doesn't require self-hosting a server to use;
• is end-to-end encrypted when traffic crosses the public internet;
• has clipboard history, not just "the latest item".

That is a narrower combination than it sounds. Most tools cover three or four of those, but tripping on one of them. This guide goes through the realistic options by category, says when each is genuinely the better fit, and explains where UniClipboard sits.

UniClipboard is one of the projects in this space — full disclosure, this guide is published on its site. The goal here isn't to dunk on alternatives. They're often great at what they do. The goal is to help you pick the right one for what you actually need.

TL;DR

• KDE Connect — best if you mostly want phone ↔ Linux desktop. Cross-desktop sync is not its design center.
• Synergy / Barrier / Deskflow — best if your machines all sit on one desk and you want shared keyboard/mouse with clipboard-as-side-effect. KVM-first, not network-first.
• Syncthing or Tailscale + a script — works, especially if you already run them. Not a clipboard tool by itself; you'll wire the clipboard part yourself.
• ClipCascade — best if you specifically want a self-hosted clipboard server with a web dashboard and Android support.
• UniClipboard — best if you want open source + Mac/Win/Linux + no cloud account + no self-hosted server + end-to-end encryption in one package, plus encrypted clipboard history.

If your requirement set matches that last bullet, UniClipboard is what this site is built for. If it doesn't, the other options below are likely a better fit.

What "good" actually looks like for cross-OS clipboard sync

Before comparing tools, it helps to be specific about what makes clipboard sync feel right.

• Latency is the hidden requirement. Clipboard sync feels broken if it takes a few seconds. The mental model is "copy here, alt-tab, paste". If it takes a noticeable pause, you stop trusting it and start scp-ing things again.
• Content type matters. Text is easy. Images are annoying. File references are more annoying — and often the moment that exposes whether a tool was really designed for clipboards or for "just text snippets".
• The network has to be ugly-tolerant. Most desktops sit behind home routers, NATs, and corporate VPNs. A tool that only works on the same LAN — or only with both machines on the same Tailscale — has narrowed itself out of "actually works for me".
• Privacy isn't optional for clipboards. People copy passwords, tokens, 2FA codes, half a config file. If a tool sends that to a server in plaintext, "open source" alone doesn't fix it.
• History is a separate feature from sync. A clipboard manager remembers what you copied earlier. A clipboard sync sends the latest item somewhere else. The good tools do both, locally and privately.

Now the categories.

The categories of open-source clipboard sync

1. Mobile-pairing tools (KDE Connect, GSConnect, etc.)

Best when: your primary need is phone ↔ Linux desktop, ideally with notifications, file sharing, and clipboard as one of several features.

Strengths:

• Mature, packaged in most Linux distros.
• KDE-integrated UX is excellent on KDE Plasma.
• Free, open source.
• Clipboard is one feature among many — handy if you also want notifications, media controls, file send.

Why it's not the answer for Mac+Win+Linux:

• Cross-desktop (Mac/Win/Linux) sync isn't the design center.
• Mac and Windows support exists in various forks but isn't first-class.
• Clipboard sync is a side feature, so history, search, and reliability are not the main investment.

If your three devices are an Android phone, a Linux laptop, and another Linux box, KDE Connect is genuinely a great answer. If they're a MacBook, a Windows desktop, and a Linux box, you'll feel the gap.

2. KVM-first tools (Synergy, Barrier, Deskflow, Input Leap)

Best when: all your machines sit on one desk, and you want one keyboard and mouse to drive several screens, with the clipboard following the cursor.

Strengths:

• Solid, long-running open-source roots (Barrier → Deskflow / Input Leap).
• Cross-platform across macOS, Windows, and Linux.
• The "mouse glides between screens" UX is unmatched if that's what you want.

Where they're not optimized:

• Clipboard is a side effect of being a KVM, not the main feature. There's no clipboard history, no encrypted local search.
• File sync is partial: it often degrades to "filename as text" rather than a real file reference. Image clipboard sync exists in Barrier but is slow on large images. (See Barrier issues #1507 and #971 for context.)
• These are client/server designs: one machine runs the server, others connect to it. The server has to be running for sync to happen.
• Cross-network usage typically requires a VPN or tunnel; they're built for one local network.

If your day looks like "two screens on the same desk, mouse glides between them," Synergy / Deskflow is genuinely better than a clipboard-only tool. If your day looks like "work laptop on a corp VPN, home desktop on a different network, both need to share clipboard," they don't really solve that without standing up another VPN tunnel between them.

3. Roll-your-own with Syncthing or Tailscale

Best when: you already run Syncthing or Tailscale for other reasons and you're comfortable wiring up your own clipboard glue.

Strengths:

• These are excellent tools. Syncthing has years of real-world sync experience baked in. Tailscale gives you a private mesh between your devices with very little setup.
• Both are open source (Syncthing fully, Tailscale's clients).
• If you already have either running, the marginal cost of wiring a clipboard hook is small.

Where it gets awkward:

• Syncthing is folder sync. Clipboard sync built on top of it usually means "watch a file, copy from it, write to it" — which is fine for a script but introduces filesystem polling latency. Sub-second clipboard sync is hard with that loop.
• Tailscale + a script works, but it's two pieces of infrastructure (Tailscale daemon + your script) on every machine, plus you still need to write the cross-platform clipboard API code, and still need to handle history yourself.
• Neither approach gives you encrypted clipboard history or full-text search out of the box. You'd build those.

If you already live inside Tailscale and you enjoy maintaining personal scripts, this is a reasonable path. For most people, "install one app on each machine" is less work than "deploy two daemons and write the connector".

4. Self-hosted clipboard servers (ClipCascade)

Best when: you specifically want to own and operate a clipboard server, with a web dashboard, server-side configuration, and Android support today.

Strengths:

• Open source, self-hostable via Docker or a Java JAR.
• Includes Android client support.
• A central server you control is good for centralized account management or policy.
• Public community server exists if you don't want to self-host yet.

Where the cost shows up:

• Self-hosting a clipboard server means container, volumes, possibly an exposed port, reverse proxy, signup policy, updates — clipboard sync becomes a small production service.
• For users who don't already operate a homelab, that's a non-trivial maintenance commitment for one feature.

If self-hosting is part of your requirement (compliance reasons, homelab pride, Android first), ClipCascade is a legitimate answer. If your actual goal is "I just want my clipboard to follow me without trusting a vendor cloud," see the next category.

For a deeper comparison, see ClipCascade alternative: open-source clipboard sync without running a server.

5. Accountless P2P clipboard tools (UniClipboard)

Best when: you want all of these at once — open source, Mac/Win/Linux, no cloud account, no self-hosted server, end-to-end encryption across the public internet, and a real local clipboard history.

What it is:

• Open-source desktop app for macOS, Windows, and Linux.
• Built in Rust + Tauri 2; uses iroh for peer-to-peer connectivity and NAT traversal.
• Devices pair directly with each other — no UniClipboard cloud account, no signup, no server you have to host.
• End-to-end encrypted across networks. When direct P2P fails, traffic falls back to an encrypted relay; the relay sees ciphertext and routing metadata, not clipboard content.
• Encrypted local clipboard history with full-text search across what you've copied.
• Text, image, and file clipboard support on desktop.

Honest limitations:

• Mobile is now available. iOS is in public beta on TestFlight and there is a native Android app (signed APK); the SyncClipboard protocol also works as a LAN fallback. For a longer-established mobile story, ClipCascade and KDE Connect are still strong.
• Younger than libp2p / Syncthing. The networking stack (iroh) is solid but evolving — see the design notes in Why I picked iroh for UniClipboard if you care about that layer.
• Not a KVM. If you want one keyboard/mouse across machines on one desk, Synergy/Deskflow is the right tool, not UniClipboard.

UniClipboard is the project this guide is published by, so treat the framing accordingly. The honest version is: it was built specifically for the gap left by the other categories above — three desktops, no cloud account, no server to host, real privacy, and a queryable history.

A side-by-side table

Requirement	KDE Connect	Synergy / Deskflow	Syncthing+script	Tailscale+script	ClipCascade	UniClipboard
Open source	Yes	Yes	Yes	Clients yes	Yes	Yes
macOS / Windows / Linux all first-class	Linux-first	Yes	Yes	Yes	Yes	Yes
Works without a cloud account	Yes	Yes	Yes	Tailscale account	Server account	Yes
Works without self-hosting a server	Yes	Server one of your machines	Discovery server / relays	Tailscale infra	Self-host or community server	Yes
End-to-end encrypted across the internet	LAN-focused	LAN-focused	Yes	Yes	Yes (per README)	Yes
Clipboard history with search	No	No	Build it	Build it	Not core	Yes (encrypted)
Image / file clipboard sync	Partial	Partial	Build it	Build it	Yes	Yes
Android client today	Yes	No	Yes (file sync only)	Yes (Tailscale, not clipboard)	Yes	Yes (native app)
Best fit	Phone ↔ Linux	KVM on one desk	DIY folder sync	DIY mesh	Self-hosted server	Accountless desktop sync

Footnote: ClipCascade behavior is summarized from its README at https://github.com/Sathvik-Rao/ClipCascade. Verify against the project for the current behavior before relying on it.

How to pick

Run through this in order:

1. Do you need mobile today? If yes, and primarily Android ↔ Linux, look at KDE Connect. If you need Android plus desktops with a server you control, look at ClipCascade.
2. Are all your machines on one desk and you want one keyboard/mouse? Use Synergy / Deskflow / Input Leap. Clipboard will follow the cursor.
3. Do you already operate Tailscale or Syncthing and enjoy gluing things together? A clipboard hook on top of those is a reasonable weekend project.
4. Do you want to own and operate a clipboard server? ClipCascade is built for that.
5. Do you want the open-source / accountless / no-server / E2EE / history combination across Mac+Win+Linux without homework? That's the slot UniClipboard is built for.

If you answered yes to anything before step 5, that earlier tool is probably the right call.

Why the relay distinction matters

If you've read this far, you've probably noticed every option has some "trust" question.

• KDE Connect / KVM tools: usually LAN-only, so trust is local network access.
• Tailscale: trust includes Tailscale's control plane.
• ClipCascade self-hosted: trust is your own server, which you have to run correctly.
• ClipCascade community server: trust is the server operator.
• UniClipboard: when direct P2P succeeds, traffic doesn't touch a third party. When it falls back to relay, the relay sees ciphertext and routing metadata.

For UniClipboard specifically, the relay can see:

• encrypted bytes (ciphertext);
• source and destination peer IDs (for routing);
• byte counts and timing.

It can not see:

• clipboard content;
• clipboard type (text / image / file);
• device names;
• the pairing passphrase.

That's a property of the cryptography, not a marketing promise. The encryption layer is independent of the transport layer; the relay is treated as an untrusted hop. If you want to verify, the code is on GitHub.

A grounded recommendation

If you've genuinely tried a few of the tools above and ended up in a slightly different one for each pair of machines, you're not alone. The category is fragmented because the design centers are different.

For the specific intersection — open source, Mac+Win+Linux, no cloud account, no self-hosted server, E2EE across the public internet, with encrypted clipboard history — UniClipboard is the project that was built for that exact intersection. It's not "better than KDE Connect" or "better than Synergy". It's a different shape, aimed at the requirement set above.

If your requirement set is different, the other tools in this guide are honestly good at what they do.

FAQ

What is the best open-source clipboard sync for Mac, Windows, and Linux?

There's no single winner — it depends on whether you also need mobile, whether you want a self-hosted server, and whether you're okay with a cloud account. For sync across desktops and mobile with no account and no server to host, UniClipboard fits that gap. For mobile-included with a self-hosted server, ClipCascade is a strong choice. For shared keyboard/mouse on one desk, Synergy / Deskflow is better than any clipboard-only tool.

Does UniClipboard work without a cloud account?

Yes. There is no UniClipboard account, no Apple ID requirement, no Google account, and no vendor login. You install the app on each desktop and pair the devices directly. Pairing is a passphrase between the two devices; UniClipboard's servers are not in the loop for clipboard content.

Does UniClipboard require running my own server?

No. It's not self-hosted. Devices pair peer-to-peer and connect directly when the network allows. When direct connection isn't possible, an encrypted relay forwards bytes between devices — the relay can't read clipboard content because everything is encrypted before transport. If you want LAN-only behavior, that mode exists.

Is clipboard sync over the public internet safe?

It depends on the tool. Clipboard sync is only as safe as its weakest network hop. UniClipboard's design is end-to-end encryption with the transport layer (including any relay) treated as untrusted. KDE Connect and Synergy-family tools were designed for trusted local networks, not arbitrary internet links. Self-hosted tools like ClipCascade move the trust to your own server. Pick the model whose trust assumptions match your real-world environment.

Does UniClipboard support Android or iOS?

Yes. iOS is in public beta on TestFlight and there is a native Android app (signed APK); the SyncClipboard protocol also works as a LAN-only fallback. ClipCascade and KDE Connect remain solid if you want a longer-established mobile client.

What about clipboard history — does any sync tool actually keep one?

Most sync-focused tools sync the latest clipboard item only and don't keep a queryable history. KVM-first tools (Synergy / Barrier / Deskflow) don't keep history. Roll-your-own setups don't unless you build it. UniClipboard keeps an encrypted local history with full-text search across what you've copied. ClipCascade focuses on sync rather than rich local history.

What's the catch with UniClipboard?

Two honest catches. First, iOS is still in public beta (Android ships as a signed APK). Second, the underlying P2P stack (iroh) is younger than libp2p or Syncthing's protocol — there's been some 0.x churn, though the API surface UniClipboard relies on is small. If those are deal-breakers for you, one of the other tools in this guide may be a better fit.

Try UniClipboard

If your requirements are open source, all three desktops, no cloud account, no self-hosted server, and end-to-end encryption across the public internet, UniClipboard is built for exactly that intersection.

• Website: https://uniclipboard.app
• GitHub: https://github.com/uniclipboard/uniclipboard

If you find a tool that fits the same requirement set better, please tell us — we'd rather use it than market against it.

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