Instant replay for Windows games.
Press a key or say your phrase, and the last five minutes are saved.
Free, open source, offline, and so light you'll forget it's on.
English · العربية · 简体中文 · Русский · Español · Português (Brasil) · Deutsch
Kairos-trailer.mp4
Why Kairos
- Never miss the moment. Kairos keeps the last 15 seconds to 20 minutes in memory (5 by default). Press
Alt+F10and it becomes a clip. - Smart Save. Record a phrase of your own, in any language, then just say it to save a clip or take a screenshot. It runs offline.
- Light. It records on your graphics card. Measured while a game ran at 1440p60 AV1: 0.4% CPU, no dropped frames.
- Edit in place. Cut, change the speed, add text, draw, blur, and make auto captions on your own PC.
- Share in one press. Post to X, TikTok and Instagram, or all three at once with one caption, or copy the clip and paste it anywhere.
- Private. No account, no telemetry. Your clips stay on your PC until you share them.
Screenshots
 Instant replay, recording and screenshots at a glance |
 Every clip and screenshot, by day and by game |
 The editor, with auto captions made on your PC |
 Post to X, TikTok and Instagram for you |
 Smart Save: say your phrase to save |
 Sign in once; sign-ins stay on your PC |
Download
- Download Kairos-Setup.exe from the latest release.
- Run it and follow the steps: pick your language and the folder (no administrator rights needed), and whether you want a desktop shortcut and Kairos to start with Windows.
- Play, then press
Alt+F10when something happens.
Windows may warn about an unknown publisher (the installer is not signed yet): choose More info, then Run anyway. Updates come from inside the app, and never during a recording. Uninstalling keeps your clips and settings.
Needs: Windows 10 (2004 or newer) or Windows 11, 64-bit. A graphics card with a video encoder (NVIDIA, AMD or Intel) is recommended.
Features
Everything Kairos does
- Capture: full screen, one window, or games (picked up automatically), up to 4K at 30 to 240 fps.
- Encoding: AV1, HEVC or H.264 on NVIDIA (NVENC), AMD (AMF) or Intel (Quick Sync), with x264 as a fallback.
- Audio: system sound and microphone, optionally on separate tracks.
- Recording: start, pause and stop with hotkeys; a paused recording stays one file.
- Screenshots with their own hotkey, saved beside your clips.
- Library: clips and screenshots by day, filtered by game, with a folder size limit that sends the oldest to the Recycle Bin.
- Editor: cut and join, speed and sound per part, text in many fonts and styles, auto captions, drawing, shapes, blur, filters, and crop for screenshots.
- Auto captions: Whisper on your graphics card. The engine and model are downloaded once, after you agree, and can be removed in Settings.
- Share: X, TikTok, Instagram, or all of them, through each site's own page; trim on a frame strip and crop to 9:16.
- Seven languages: English, Arabic, Chinese, Russian, Spanish, Portuguese and German. The first run follows your Windows language.
- Quiet: starts with Windows in the tray, with no pop-ups or sounds unless you turn them on.
Privacy
- No telemetry, no analytics, no Kairos account.
- Kairos goes online only when you ask: to post what you share, to download auto captions once, and to check this page for a newer version once a day (you can turn that off).
- Smart Save and auto captions listen on your PC only.
Build from source
For developers
Kairos is a .NET 10 app (WPF and WinForms) that hosts libobs, the engine of OBS Studio, with only the modules it needs, and uses FFmpeg for editing and sharing.
.\tools\build-whisper.ps1 # once: the auto captions engine (needs the Vulkan SDK and VS Build Tools) .\tools\release.ps1 # the Setup, update files and source zip in releases\ (needs vpk 1.2.161) dotnet run --project tests\Kairos.Tests # the tests
The build copies libobs 32.2.2 from an installed OBS Studio.
License
Kairos is free software under the GNU General Public License v2.0 or later, the same license as libobs. Every release includes its complete source code. Third-party components and their licenses are listed in THIRD-PARTY-NOTICES.md.
Kairos (καιρός) is Greek for the right moment.