kinrec

Mac screen + audio → mp4. One binary, go install, no Electron.

kinrec is an open-source screen recorder for macOS. It's pure Go, no cgo, no app bundle, no Electron, no subscription. One command:

go install github.com/LocalKinAI/kinrec/cmd/kinrec@latest
kinrec record -o demo.mp4 --audio --duration 30s

Why

Recording your Mac screen today looks like this:

Tool	Problem
QuickTime (built-in)	No hotkeys, no system audio, no shortcuts
`screencapture -v` CLI	Can't record system audio
OBS	200 MB download, Mac is a second-class citizen
CleanShot X	$29, closed source
Screen Studio	$89, closed source
Loom	Subscription, login required
Kap (open source)	Abandoned since 2022, Electron-based
aperture-node	Abandoned, macOS 15+ broken

Everyone recording a screencast either pays, juggles OBS, or watches their recorder break with each macOS update.

kinrec is what happens when you start from scratch in 2026:

One command: go install + kinrec record -o x.mp4 --audio.
5 MB binary, not a 200 MB Electron bundle.
Hardware H.264 / HEVC via VideoToolbox — no ffmpeg needed.
System audio via ScreenCaptureKit's native audio path (macOS 14+; skips the feedback loop from your own process).
macOS 15 / 26 ready — built on the modern SCStream + AVAssetWriter pipeline, not the deprecated CGDisplayCreateImage path that every other Go recorder (and many commercial ones) used.
Pure Go downstream: the ObjC dylib is embedded via //go:embed and auto-extracted. Your users never need clang, CGO_ENABLED, or a Mac developer toolchain.
Built on sckit-go — the same low-level ScreenCaptureKit bindings power both libraries.

Install

go install github.com/LocalKinAI/kinrec/cmd/kinrec@latest

That's it. No Homebrew cask, no .dmg, no signing ceremony.

First run triggers macOS permission prompts. Grant "Screen Recording" in System Settings → Privacy & Security → Screen Recording. If you use --mic, also grant "Microphone" on first use. Both permissions are per-binary and persist.

Usage

Record until Ctrl+C

kinrec record -o demo.mp4

Timed recording

kinrec record -o tutorial.mp4 --duration 5m

With system audio (what apps on screen play)

kinrec record -o meeting.mp4 --audio --duration 30m

Captures what Chrome / Spotify / Zoom / any app sends to the speakers. Your microphone is not recorded — use --mic for that.

With microphone (your voice — for tutorials)

kinrec record -o tutorial.mp4 --mic --duration 5m

Captures from the default input device. Triggers a one-time macOS "Microphone" permission prompt on first use.

Short-video preset (`--shorts`)

kinrec record --shorts -o clip.mp4 --duration 60s

One flag applies the X / TikTok / YT Shorts / Reels defaults: 1080×1920 vertical, 30 fps, --audio + --mic both on (mixed into a single track via AVAudioEngine). Any explicit --fps / --resolution / --audio / --mic you pass still wins.

Cursor highlight + click ripple (`--click-highlight`)

kinrec record --click-highlight -o tutorial.mp4 --mic --duration 2m

Draws a subtle white ring around the cursor at all times and a yellow expanding ripple every time you left-click. Matches the effect Screen Studio ($89) built its brand on. Requires no Accessibility permission.

Current v0.1 limits: works on Display-target capture at the display's native resolution. --click-highlight --shorts or --click-highlight --resolution WxH will misalign the overlay until coordinate mapping is generalized in v0.2.

Pick a specific mic

kinrec list mics
kinrec record -o demo.mp4 --mic --mic-device=<unique-id>

Mix: system audio + mic together (the Loom default)

kinrec record -o tutorial.mp4 --audio --mic --duration 5m

Both sources flow into an AVAudioEngine pipeline (two player nodes → main mixer → tap), and the mixed PCM is encoded to a single AAC track. Use this for:

Tutorials where you narrate over a video playing on screen
Zoom recordings that capture both yourself and the other side
Podcasts that include desktop-app audio

Custom framerate + resolution

kinrec record -o demo.mp4 --fps 30 --resolution 1280x720

HEVC for ~30% smaller files

kinrec record -o demo.mov --codec hevc --format mov

Pick a specific display

kinrec list displays
kinrec record -o ext.mp4 --display 2

Full flag reference

kinrec record [flags]

  -o, --output PATH      Output path (required)
      --duration D       Stop after this long (30s, 5m, 1h); 0 = Ctrl+C
      --fps N            Target frame rate (default 60)
      --resolution WxH   Output size (default: display native)
      --audio            Capture system audio (what apps play)
      --mic              Capture microphone (your voice)
      --mic-device ID    Mic AVCaptureDevice uniqueID (see `kinrec list mics`)
      --codec h264|hevc  Video codec (default h264)
      --format mp4|mov   Container (default mp4)
      --display ID       Specific display ID (default: main)
      --shorts           Vertical 1080x1920 + 30fps + audio + mic preset
      --click-highlight  Overlay cursor ring + click ripple (for demos)

Use as a library

package main

import (
    "context"
    "log"
    "time"

    "github.com/LocalKinAI/kinrec"
)

func main() {
    ctx := context.Background()
    err := kinrec.Record(ctx, 10*time.Second,
        kinrec.WithOutput("/tmp/demo.mp4"),
        kinrec.WithAudio(true),
        kinrec.WithFrameRate(60),
    )
    if err != nil {
        log.Fatal(err)
    }
}

For fine-grained control (start/stop pairs, live stats):

r, err := kinrec.NewRecorder(ctx,
    kinrec.WithOutput("demo.mp4"),
    kinrec.WithAudio(true),
)
r.Start(ctx)

go func() {
    for range time.Tick(time.Second) {
        s := r.Stats()
        log.Printf("frames=%d audio_bufs=%d", s.Frames, s.AudioBuffers)
    }
}()

<-someSignalToStop
r.Stop(ctx)

Output

All recordings are real mp4 / mov files with:

Video: H.264 High profile or HEVC, yuv420p, hardware-encoded via VideoToolbox (≈ 5 bits per pixel per 30fps-second baseline bitrate).
Audio (when --audio): AAC-LC, 48 kHz stereo, 128 kbps.
Container: mp4 (default, web-compatible) or mov.
Playable in QuickTime, Safari, Chrome, VLC, Premiere, DaVinci, iMovie.

Verified with ffprobe on a 5-second --audio capture:

Stream #0: Video: h264 (High), yuv420p, 1920x1080, 894 kb/s, 30 fps
Stream #1: Audio: aac (LC), 48000 Hz, stereo, 128 kb/s

Roadmap

v0.1.0 — Recorder foundation (shipped 2026-04-23)

v0.2.0 — Quality of life

Window / app / region recording (via sckit-go target pass-through)
Progress bar with estimated file size
Automatic file-size limit (--max-size 500M)
Dual-track mode as an opt-in (--audio --mic --dual-track) — useful for editors who want to adjust the two sources independently

v0.3.0 — The magic features

Click highlight / ripple effects (the thing CleanShot charges $29 for)
Cursor smoothing
Auto-zoom on click (the thing Screen Studio charges $89 for)
Keystroke display (show ⌘C on screen when pressed)
Webcam picture-in-picture overlay

v0.4.0 — Share + edit

R2 / S3 upload with shareable link (--upload --share)
GIF export (--gif)
Timeline trim post-recording
Automatic thumbnail generation

v0.5.0 — UI (optional, if demand exists)

Menu bar app (SwiftUI wrapper around the same binary)
Global hotkey daemon

Architecture

  Go code
    │
    │  purego.RegisterLibFunc (no cgo)
    ▼
  libkinrec_writer.dylib  (~190 KB universal arm64+x86_64, //go:embed'd)
    │
    ├─── SCStream (video + audio capture)
    └─── AVAssetWriter (H.264 / HEVC + AAC mux)
                 ↓
              out.mp4

The dylib is ~400 lines of ObjC (objc/kinrec_writer.m). It wraps ScreenCaptureKit's async delivery with dispatch_semaphore + a SCStreamOutput delegate, forwards each CMSampleBuffer to an AVAssetWriterInput, and blocks on finishWritingWithCompletionHandler when the caller stops.

Hardware encoding is provided by AVAssetWriter selecting VideoToolbox automatically based on the codec key (AVVideoCodecTypeH264 / AVVideoCodecTypeHEVC). No external ffmpeg dependency.

Requirements

macOS 14 (Sonoma) or newer — SCStreamConfiguration.capturesAudio lands in macOS 13 but the full API matures in 14.
Xcode Command Line Tools (contributors only; downstream users do not need them thanks to //go:embed).
Go 1.22+.

Development

git clone https://github.com/LocalKinAI/kinrec
cd kinrec

make help           # list targets
make dylib          # build universal libkinrec_writer.dylib
make cli            # build ./kinrec
make verify         # build + vet + record a 3-second clip
make install-cli    # go install ./cmd/kinrec to $GOBIN

Layout

kinrec/
├── kinrec.go           # Load + Recorder + Record convenience
├── options.go          # functional options
├── cmd/kinrec/
│   ├── main.go         # subcommand dispatch
│   ├── record.go       # `kinrec record`
│   ├── list.go         # `kinrec list displays`
│   └── version.go
├── objc/
│   └── kinrec_writer.m # SCStream → AVAssetWriter pipeline
└── internal/dylib/
    ├── dylib.go        # //go:embed
    └── libkinrec_writer.dylib

License

MIT — see LICENSE.

Built by LocalKin AI on top of sckit-go. Dogfood of the primitive capture library — proves that sckit-go is strong enough to build full products on.

Name		Name	Last commit message	Last commit date
Latest commit History 4 Commits
cmd/kinrec		cmd/kinrec
internal/dylib		internal/dylib
objc		objc
.gitignore		.gitignore
.golangci.yml		.golangci.yml
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
Makefile		Makefile
README.md		README.md
ROADMAP.md		ROADMAP.md
go.mod		go.mod
go.sum		go.sum
integration_test.go		integration_test.go
kinrec.go		kinrec.go
kinrec_test.go		kinrec_test.go
options.go		options.go
options_test.go		options_test.go

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kinrec

Why

Install

Usage

Record until Ctrl+C

Timed recording

With system audio (what apps on screen play)

With microphone (your voice — for tutorials)

Short-video preset (--shorts)

Cursor highlight + click ripple (--click-highlight)

Pick a specific mic

Mix: system audio + mic together (the Loom default)

Custom framerate + resolution

HEVC for ~30% smaller files

Pick a specific display

Full flag reference

Use as a library

Output

Roadmap

v0.1.0 — Recorder foundation (shipped 2026-04-23)

v0.2.0 — Quality of life

v0.3.0 — The magic features

v0.4.0 — Share + edit

v0.5.0 — UI (optional, if demand exists)

Architecture

Requirements

Development

Layout

License

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Short-video preset (`--shorts`)

Cursor highlight + click ripple (`--click-highlight`)

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