remotedesktop 0.20.1

Remote desktop client/server for Windows computers on the same LAN, with autodiscovery. Provides screen, keyboard, mouse, and clipboard sharing without RDP or Microsoft authentication.

Remote Desktop

Lossless, low-latency remote desktop for Windows computers on your LAN — pure Python, zero configuration.

Run the server on the computer you want to reach and the client anywhere else on the network: the server is discovered automatically, the first connection is approved with one click on the server side, and from then on the client reconnects instantly whenever the server is running. The screen stream is pixel-exact at full resolution — built for documents, code, and terminals rather than video — captured with DXGI desktop duplication and delta-compressed so only the parts of the screen that changed are sent. No Windows RDP, no Microsoft accounts, no cloud: just two apps and your LAN.

See it in action

Client

The client discovers the server on the LAN, connects, and streams its desktop live in a tab named after that computer — click into the view and your mouse and keyboard control the remote machine. Connect to several servers at once and each gets its own tab; the window title lists every connected computer. The Performance tab graphs bandwidth and round-trip time with live statistics.

Server

The server's Status tab shows every connected viewer — who they are (login name, computer, OS) and how the connection is doing (bandwidth, round-trip time with mean/min/max/p99/jitter over the recent window).

Features

• 🔍 Autodiscovery — servers announce themselves over UDP; the client lists every server on the LAN, no addresses to type.
• 🗂️ Multiple servers at once — one client can view and control several servers simultaneously, each in its own tab named for that computer; the window title shows who you're connected to, even minimized.
• 🖥️ Lossless screen sharing — pixel-exact at full resolution, DXGI desktop-duplication capture (~10 ms per 4K frame), and inter-frame delta compression: an unchanged screen sends nothing.
• ⌨️🖱️ Full input control — mouse, wheel, and keyboard forwarding that is safe against interruptions: anything still held down is released on the server if the viewer loses focus or disconnects, so no stuck keys.
• 📋 Two-way clipboard — text and images copied on either machine appear on the other.
• 🔒 TLS + approve-once pairing — every connection is encrypted; the server user approves a new client once, after which it reconnects with a stored token and no prompt.
• 📊 Built-in performance monitoring — live bandwidth and round-trip-time graphs with window statistics (mean/min/max/p99/jitter), plus a per-viewer table on the server.
• 🔁 Robust connections — dead connections are detected and dropped within seconds, and approved clients reconnect automatically without ceremony.
• 🚀 Hands-off operation — optional start-at-login (per-user, no admin rights) and a Restart server button usable from the remote session itself, so you can update the software without visiting the machine.
• 🗃️ Persistent peer inventory — both apps keep a SQLite-backed history of every peer seen on the LAN, with one-click revoke access / forget server.

In scope: screen, keyboard, mouse, and clipboard. Out of scope: shared drives, devices, and audio — and smooth playback of fast-changing full-screen content (video, games) is a non-goal; the stream is optimized for mostly-static desktop work.

Installation

pip install remotedesktop

or, with uv:

uv tool install remotedesktop

Or run straight from a clone of this repository: double-click run_server.bat on the computer to be shared and run_client.bat on the viewing computer — each prepares the environment on first use and launches the app.

Quick start

1. On the computer to share, run remotedesktop-server.
2. On the viewing computer, run remotedesktop-client — the server appears in its Servers panel; double-click it.
3. Approve the connection in the dialog that pops up on the server. That's it — future connections from that client need no approval.

From a terminal in a clone of this repo, the same apps run with uv run remotedesktop-server and uv run remotedesktop-client.

Security model

Connections are TLS-encrypted with a self-signed certificate the server generates once and keeps. The trust model is tuned for a trusted LAN: certificates are trusted on first use and a changed fingerprint is logged rather than blocking the connection, favoring reliable reconnection over strict certificate checking. Unapproved clients are limited to small handshake messages until the server user admits them; access can be revoked at any time from the server's Clients on LAN tab. There is no dependency on Windows RDP or any Microsoft-based authentication.

How it works

All of this is pure Python — the GUIs are PySide6 (Qt), and the two places that need to talk to Windows directly (screen capture and input injection) call the Win32/COM APIs through ctypes, so there are no native extensions to compile.

Screen capture. The server grabs the desktop with the DXGI desktop duplication API, driven directly through ctypes COM calls. Desktop duplication is the mechanism Windows provides for exactly this job: the compositor hands over a GPU texture of the screen and tells you whether anything changed, so a changed 4K frame costs about 10 ms to read back and an idle screen costs essentially nothing. When duplication is unavailable or gets lost — the secure desktop (UAC/logon screen), an RDP session, a display-mode change — the server transparently falls back to Qt's QScreen.grabWindow (~96 ms per frame) and keeps retrying duplication in the background.

Screen transfer. Frames are captured at up to 30 fps and compared with the previous capture in 64-row bands; only the bands that changed are encoded — losslessly, as PNG — and sent as a delta the client patches onto its last frame. An unchanged screen sends nothing at all. Full PNG keyframes go to clients that just connected, fell behind (a client whose socket backlog grows gets frames dropped, then a fresh keyframe once it catches up), or asked for one because a delta failed to apply — so a desynced stream heals itself. The frame always travels at the server's full resolution; scaling to the viewer window happens on the client.

Input injection. The client's viewer widget captures your mouse and keyboard events, maps mouse positions to coordinates normalized 0..1 over the displayed frame (so window size and letterboxing don't matter), and sends them as small JSON messages. The server injects them with the Win32 SendInput API: normalized coordinates map onto SendInput's 0..65535 absolute coordinate space over the primary monitor, and keystrokes carry the client's native virtual-key codes, which are injected as-is — both ends are Windows, so no key translation is needed. The server only injects input from clients that have passed the approval handshake, and anything still held down (a dragged button, a modifier key) is released automatically if the viewer disconnects or loses focus.

Clipboard. Both sides watch their local clipboard via Qt and forward copies (text, or images as PNG) over the same connection. Echo loops are prevented by content signature — an image is hashed by its canonical pixels, so a PNG that makes a round trip through the OS clipboard and comes back re-encoded is still recognized and not sent again.

Transport. Each client talks to the server over a single TCP connection: TLS via the Windows schannel backend with a self-signed certificate the server generates and keeps, then simple length-prefixed messages on top — JSON for control (hello/welcome, input, clipboard, ping/pong for the round-trip-time graphs, log exchange) and binary payloads for frames and deltas. Discovery is a UDP broadcast probe that every server answers with its name and port (see below).

Versioning

The apps follow semantic versioning: the major version is the client/server compatibility contract (same major → guaranteed to interoperate), minor versions add backward-compatible features, patch versions fix bugs. On every connection each side compares its major version with the peer's; a mismatch shows a strong warning in both GUIs — connecting is still allowed, but the experience is not guaranteed. Keep both computers on the same version for best results.

Requirements

• Windows
• Python 3.14+

How discovery works

The client broadcasts a small JSON probe over UDP (port 48653); each server on the LAN replies with its hostname and connection port. Windows Firewall must allow Python to receive inbound UDP on that port for a server to be discoverable from other machines.

Development

uv sync          # set up the environment
uv run pytest    # run the tests

Run the tests from PowerShell or cmd, not Git Bash: Git Bash puts Git's MinGW OpenSSL DLLs on PATH, which Qt's TLS backend loads and crashes on. From PowerShell, Qt uses the Windows schannel backend as intended.

The demo GIFs above are generated — entirely from synthetic data — by uv run python tools/make_demo_gifs.py.

The badges branch

The coverage badge above is served from the badges branch (raw.githubusercontent.com/.../badges/coverage.svg). CI regenerates the SVG after each test run on master and force-pushes it there as a single orphan commit. It lives on its own branch because master only accepts pull requests (a repository ruleset), so CI cannot commit to it directly; keeping the badge in the repo avoids depending on an external coverage service. The branch is generated output — never branch from it or merge it.