For two tools, yes: Image → Splat and Remove People need one. It's recommended for Video → Splat but not required — a CPU build of the camera solver installs automatically and the trainer runs on any modern GPU, just slower. Importing, relighting and editing don't need anything special.

You do. The addon is GPL-3.0 like every Blender addon; splats you import, train or generate — and anything you render with them — are yours, for commercial work included.

Both, including the gaussian self-shadows. EEVEE for speed with hashed transparent shadows, Cycles with shadow rays that absorb through the gaussians. Cycles is not recommended though as it is quite intense performance wise.

Almost nothing. Video → Splat (360° footage and Remove People included), Mesh → Splat and Image → Splat run entirely on your machine — no account, nothing uploaded. The one exception is Prompt → World, which is a bridge to World Labs Marble, a separate paid service: you bring your own API key and pay-as-you-go credits (about $1.20 a world, $5 minimum, no subscription). Marble is not included with Splatlight, and the other generators don't need it.

Yes (PRO). One click builds a watertight proxy mesh, you bind the splats to it, and then it behaves like any mesh — armatures with automatic weights, lattices, shape keys, cloth, softbody.

.ply (standard and compressed), .sog including tiled LOD scenes, and 4D clips — a .ply per frame or a single SpacetimeGaussians .ply — with timeline playback, several clips at once, each at its own speed (playback is PRO). Export is standard .ply; PRO adds per-frame .ply sequence export.

Yes, if you bake it (PRO). Baking writes your lighting into a per-splat attribute, and the exported standard .ply keeps the relit look in SuperSplat, PlayCanvas, or any viewer that reads .ply.

Yes (PRO). Tick 360° Video in Video → Splat and point it at equirectangular footage. Every frame is split into cube-face views that the camera solver treats as one rigid rig, so one walk through a room covers every wall. Remove People masks whoever is holding the camera out of every view first, so they never end up in the splat (needs an NVIDIA GPU; one-time ~4 GB setup).

Yes (PRO, experimental). With Track Selection you select the object's splats on one frame and a crop cage follows it through the clip; Delete Inside then removes it from every frame, or Keep Inside keeps only it. It follows the object as one rigid piece, so it suits a phone, a cup or a prop better than something that changes shape — and if it slips on a frame, you move the cage and key it there.