The short answer
On a Mac you have three realistic routes: LightBurn's paid macOS build, a generic G-code sender such as Universal Gcode Sender, or Vextrify. A generic sender moves the machine but knows nothing about engraving: no material profiles, no dithering, no camera alignment. For cutting simple vectors that is fine. For photo engraving it is not, because the result is decided before the file is sent.
LaserGRBL: Windows only, not an option on macOS
Generic senders: move the machine, no engraving knowledge
LightBurn: paid macOS build, basic image preparation
Vextrify: macOS app, GRBL and Ruida, preparation included
Why a sender alone is not enough for photos
A sender passes on what it is given. If the image still has near-white areas that burn, compressed mid tones or a dot pattern that merges on your material, the machine faithfully engraves that. Preparation is where the result is decided — material profile, tonal range, dot structure — and it has to happen before anything is sent.
Near-white that still burns leaves a grey haze
Dot pattern has to match how the material spreads the burn
A sender cannot repair any of this
Getting the Mac to see the laser
Most GRBL boards talk over a USB-to-serial chip, usually CH340 or FTDI. macOS needs the matching driver for the port to appear at all, and only one program may hold the connection at a time — if a sender is still running in the background, the next one will not connect. Check the driver first, then make sure nothing else is holding the port.
CH340 or FTDI driver has to be installed on macOS
Only one program may hold the serial port
A sender left running in the background blocks the next one
What Vextrify does on a Mac
A signed and notarised macOS app for Apple Silicon that speaks GRBL for diode lasers and Ruida for CO2 machines, aligns the job with a camera on the real workpiece, runs a dry run before anything burns, and prepares the image in the same project. If you prefer to keep another sender, it exports clean files instead.
Signed and notarised macOS build
GRBL and Ruida from the same app
Camera alignment, dry run, live job control