CNC G-code Senders

The sender is the program on your laptop / Pi / mini-PC that talks to the controller, shows you DROs and a toolpath preview, runs probing macros, and streams G-code line-by-line. LinuxCNC and Mach are senders + firmware in one box; the GRBL/FluidNC world splits the two cleanly. For laser-specific senders see Laser Design & Sender Software. For CAM that produces the G-code in the first place, see also CAM & Toolpathing.

Open-source GRBL senders

• ★ Universal Gcode Sender (UGS) — open source (GPLv3); cross-platform (Java) GRBL / TinyG / Smoothie / grblHAL sender. The FOSS default. Platform edition has a workspace with toolpath visualizer and pendant; Classic is the lighter UI. Active community, plugin ecosystem.
• ★ gSender (Sienci Labs) — open source (GPLv3); the friendliest GRBL UI for newcomers. Polished Electron app, opinionated workflow, excellent probing wizards, surfacing routine, and rotary support. Defaults shipped with Sienci LongMills but works on any GRBL/grblHAL/FluidNC machine. The "give this to a friend who just bought a Shapeoko" answer.
• ★ CNCjs — open source (MIT); Node-based browser UI; runs nicely on a Pi attached to the machine and accessed from any device. Widget-based dashboard, macro panel, probing widget. Strong for headless setups.
• ★ bCNC — open source (GPLv2); Python/Tk; ugly but powerful. Best-in-class auto-leveling probe grid for surfacing PCBs and warped stock; CAM-ish features built in. The pick when you actually need that probe-grid heightmap.
• Candle — open source (GPLv3); Windows-focused Qt sender; lean, fast, GRBL-only. Default on cheap Genmitsu / SainSmart / FoxAlien routers. Limited probing; fine for "send this file."
• OpenBuilds CONTROL — open source (MIT); designed for OpenBuilds machines (LEAD, Workbee, Sphinx) but works generically with GRBL / grblHAL / Smoothie. Pairs with the OpenBuilds CAM browser tool.
• Grbl-Plotter — open source (GPLv3); Windows-only; specializes in plotter / drag-knife / engraving from SVG/DXF directly. Doubles as a sender.

Vendor-bundled senders (free with the machine)

• Carbide Motion (Carbide 3D) — closed source, free for Carbide 3D Shapeoko / Nomad / Pro owners. GRBL-based machines only; very polished probing for the BitSetter / BitZero accessories.
• Easel (Inventables) — closed source / SaaS, free; browser CAM + sender for X-Carve and clones. The only sender on this page that's also the CAM tool.
• OneFinity Masso / Buildbotics UI — bundled with OneFinity machines; web-based on Buildbotics, touchscreen on Masso.
• Carveco Motion — paired with Carveco Maker subscriptions; works with most GRBL/grblHAL/Mach3/Mach4 setups.

FluidNC / grblHAL web UIs

• ★ WebUI 3 (FluidNC built-in) — open source; runs on the ESP32 itself. Browse the SD card, jog, run jobs, no host PC needed. The most "appliance-like" GRBL-class experience.
• ESP3D-WebUI — open source; the upstream of FluidNC's web UI; also works with grblHAL builds that include the ESP32 plugin.
• grblHAL Plugin Web Builder — drop-in browser UI for grblHAL boards with Ethernet/WiFi.

Pendants & physical jog controllers

• XHC HB04 / WHB04B — paid, cheap (~$80); USB wireless pendants; works with Mach3/4 (native), LinuxCNC (driver), UGS Platform (plugin), and CNCjs (plugin). The dominant hobby pendant.
• Ruida HC03 / CSLabs pendants — vendor-specific; Mach / Centroid land.
• OpenPendant — open source; DIY ESP32 pendant projects; mostly for FluidNC.

Senders for non-GRBL controllers

• PathPilot (Tormach), Centroid CNC12, Mach3/4 — these are senders too, but they're tightly bound to their firmware. See Controllers & Firmware.
• LinuxCNC's Axis / Touchy / GMOCCAPY — UIs are part of LinuxCNC itself; no separate sender.
• CNCjs + smoothie-grbl bridge — historical fix for running CNCjs against Smoothie; FluidNC obviated it.

Headless / remote / monitoring

• OctoPrint with OctoPrint-CNC plugin — open source (AGPLv3); the 3D-printer host adapted for CNC. Niche; CNCjs is the better dedicated tool.
• Octo4a / cncjs-pendant-tinyweb — small UIs for phones / minimal screens.
• Streamline (Carbide 3D) — closed-source remote-monitoring app for Shapeokos.

Pick this if…

• Default FOSS, cross-platform, plugins: UGS Platform.
• Newcomer / least-friction GRBL UI: gSender.
• Run on a Pi, browse from any device: CNCjs.
• Need a real probe-grid auto-leveler: bCNC.
• Cheap GRBL router on Windows: Candle (it shipped with the machine).
• Carbide 3D / Inventables / OneFinity owner: the bundled tool — they're tuned for the machine's probe and toolsetter.
• No host PC at all, FluidNC machine: the built-in WebUI is genuinely sufficient.