Bufferless quietly keeps the last minute of your screen in memory. When something worth keeping happens, press Alt+F10 and it's saved as an MP4. It's like NVIDIA Instant Replay without the overlay, the account, or the pile of background services.

• Tiny. One exe, 300 KB (or 55 KB if you want to show off). Nothing to install.
• Light. Your GPU's built-in video encoder does the work, so games barely notice.
• Instant. Saving takes about 10 ms because nothing gets re-encoded.
• Any GPU. Uses Windows' standard hardware encoders, so it should work on NVIDIA, AMD and Intel GPUs (tested on NVIDIA so far). Windows 10 and 11.

How to use it

1. Download bufferless.exe from the latest release and run it. There's no installer. A tray icon (three little circles) means it's recording.
2. Play, stream, work, whatever. It's always keeping the last minute.
3. Press Alt+F10. You'll hear a short chime, and the clip lands in your Videos\Bufferless folder, named after whatever was on screen: cs2 2026-10-02 21-14-03.mp4.

Click the "Clip saved" notification to jump straight to the file.

Tip

Windows hides new tray icons behind the ^ arrow. Drag the Bufferless icon onto the taskbar to keep it in sight.

Which download?

Every release has three versions of the same app. They behave identically.

File	Size	Pick it if...
bufferless.exe	~300 KB	You just want it to work. Start here.
bufferless-small.exe	~107 KB	You like small things.
bufferless-tiny.exe	~55 KB	You want bragging rights. It's compressed with UPX, which antivirus tools sometimes flag as suspicious.

Note

The exe isn't code-signed, so Windows may say "Windows protected your PC" the first time. Click More info, then Run anyway.

The tray icon

Right-click it for the menu, or double-click it to open settings.

Menu item	What it does
Save clip	Same as pressing the hotkey.
Open clips folder	Opens Videos\Bufferless (or wherever you pointed it).
Settings...	Opens the settings window.
Quit	Stops recording and exits.

If the icon looks faded, something's wrong (for example the GPU encoder couldn't start). Hover over it to see what's going on.

Settings

Save clip hotkey. Click the box and press the combination you want.

Replay length. How far back each clip goes, from 15 seconds to 20 minutes.

Display. Which monitor to record.

Resolution. Record smaller than your screen to save memory and disk space.

Frame rate. 60 fps is a good default. Going higher only helps if your monitor refreshes that fast.

Bitrate. Higher means sharper video but more memory. The window shows how much RAM your choice will use.

Record the mouse cursor. Draw your cursor into clips. Games that hide it stay hidden.

Audio. Record what you hear, your microphone, or both (they're mixed into one track). Pick which mic and set its volume.

Save clips to. Where clips go.

Start with Windows. Launch automatically when you sign in.

Settings are saved to %APPDATA%\bufferless\config.toml, next to a small log file.

Questions

It says the hotkey is unavailable

Another app already uses that shortcut. It's usually the NVIDIA overlay, which owns Alt+F10 for its own Instant Replay. Either turn off Instant Replay in the NVIDIA app, or pick a different hotkey in Bufferless's settings (Ctrl+Alt+F10 works well).

How much memory does it use?

Around 50 MB for the app, plus the replay buffer itself. The buffer is roughly bitrate × length: the default 20 Mbps for 60 seconds is about 150 MB. Lower the bitrate, resolution or replay length to use less. The settings window shows the estimate as you change things.

Will it slow down my games?

Barely. Graphics cards have a separate chip just for encoding video, and that's what does the heavy lifting. In testing at 1080p and 60 fps, Bufferless used about 3% of one CPU core.

My antivirus flagged it

That's almost certainly bufferless-tiny.exe. It's compressed with UPX, a tool malware also likes to use, so some scanners get suspicious of anything packed with it. Use bufferless.exe instead.

Why does my clip start a little early?

Video is stored in chunks that start every second, and a clip has to begin at the start of a chunk. So you might get up to one extra second at the beginning.

What doesn't it do (yet)?

• Cursors that invert the colours under them (like the text I-beam) are drawn in black instead.
• HDR screens are recorded in normal (SDR) colours.
• Portrait (rotated) monitors are recorded sideways.
• No trimming or editing, and no in-game overlay. That's on purpose.

How it works

The trick is that Bufferless keeps finished video in memory, not raw frames. Your screen is grabbed with Windows' Desktop Duplication, converted and compressed by the GPU's hardware encoder, and the result goes into a rolling buffer. Raw frames for a minute of 1080p would take around 30 GB; compressed, it's about 150 MB.

When you press the hotkey, Bufferless copies the buffer into an MP4 file. Nothing gets re-encoded, so it takes milliseconds, and the video looks exactly as it did when it was recorded. Audio is captured separately and lined up with the video using the same clock.

Building from source

You need Windows 10 or 11 and Rust with the MSVC toolchain.

cargo build --release

That gives you target\release\bufferless.exe, the standard build.

The smaller two are built with .\build-tiny.ps1, which needs a nightly toolchain and UPX (winget install UPX.UPX). It turns on the nostd feature, which drops Rust's standard library and the C runtime: everything the app needs from them lives in src/rt.rs as small Win32 wrappers. Pass -NoUpx to skip the packed one.

GitHub Actions builds and tests all three on every push. Each push to main is published as a release with the next patch version (v0.1.1, v0.1.2, ...); push a tag like v0.2.0 yourself for a bigger jump.

File	What's in it
src/capture.rs	Screen capture, GPU colour conversion, frame timing
src/encoder.rs	Hardware H.264 encoder
src/audio.rs	System audio and mic capture, mixing, AAC encoding
src/ring.rs	The replay buffer
src/mux.rs	MP4 writer
src/app.rs	Tray icon, hotkey, saving clips
src/settings.rs	Settings window
src/rt.rs	The tiny runtime used instead of Rust's std
src/icon.rs	Draws the app and tray icons

License

MIT. Do whatever you like with it, just keep the copyright notice.