AtomCut is a motion design and video studio that runs in a browser tab: an infinite canvas, a multi-track timeline, no account, no watermark. Version 4 adds the two things people kept asking where to find, a physics engine and real 3D worlds. This is the tour for someone who has never opened it.
Everything you see below is a frame rendered by AtomCut. They come from the launch film for version 4, which Claude built scene by scene through AtomCut's agent link. We'll get to that.
The editor: canvas, the Physics tab for the selected title (body, bounce, friction, forces, gravity) and the timeline. A real capture.
What does physics do to a title?
It drops it on the floor. Right-click any layer, choose Physics › Falls, and it falls from where it is, lands on the bottom edge of the comp and settles. Text, a logo, a sticker, a 3D mesh: any layer.
The part worth knowing is what it lands on. A rectangle is a box, but a star lands on its points, a word on its letters, a sticker on the edge of its picture. The collider is drawn dashed on the canvas so you can see what it will hit before it hits.
A 3D 4 and a pile of shapes, under two seconds, rendered in AtomCut. (On the blog version you can drag across this to scrub it.)
Scrubbing works because a physics frame in AtomCut is a function of time. You can ask for any frame in any order: scrub, loop, jump to the end, export. Nothing is baked, and there is no "bake" button hiding in a menu. Edit anything and it re-runs from the start; the rest of the time every frame reads a stored result.
Around the falling there is a small kit:
- Fixed layers are shelves and ramps. Pushes layers move by their own keyframes and shove whatever is in the way.
- Force fields live on their own layer: wind, vortex, attract, turbulence, drag. Aim one by turning it, key its strength, and a gust is two keyframes.
- Joints hold a body to the comp or to another body: pin, weld, rope, spring. A hanging sign is a pin and a swing.
- A layer that is keyed moving when physics starts keeps moving. Key a throw, start physics at its end, and it flies on.
Each comp has its own simulation settings. Gravity 981 is Earth; set it to 0 and everything floats, which is how the planets below stay up.
What is a 3D world, and why is it a comp?
A world is a composition like any other, except it contains meshes, a camera and lights instead of flat layers, and every one of them is keyed on the same timeline as everything else. Drop a world into a flat comp and it renders through its live camera, so a 3D title can sit under 2D captions without leaving the page.
Any flat layer can stand in a world: text, shapes, images, video, other comps. Text gets real thickness with bevels. Meshes get materials (gold, chrome, glass, neon, toon), modifiers (subdivision, mirror, array, bend, twist, wave, displace), and an edit mode with extrude, inset, loop cut and knife. The default keymap is Blender's, so the shortcuts you already know work.
A solar system in orbit. A point force at the sun, a starting velocity per planet, no position keyframes. (On the blog version you can drag across this to scrub it.)
Those orbits are physics, not animation. A point force sits at the sun, gravity is switched off, and each planet starts with a velocity that bends into a circle. It is the same Physics tab as the falling 4, one dimension up.
Worlds export as glTF/GLB with their motion, plus USDZ, OBJ, STL and PLY, so a scene you build here can leave for a game engine, a viewer, or a 3D printer.
Can a drawing have bones?
Yes, and they obey physics too. A rig is bones that bend your art, with IK, controls that have limits, and weight painting. Switches handle eyes, mouths and hands, and blinks run on their own.
Five moments of one hop. The antenna is a bone with Follow at 0.6, so it trails and settles by itself.
Physics reaches through the bones. Give a piece a body and it swings from its joint: a clock hand let go, a hanging lamp, a tail. Make the whole rig fall and the character tumbles with its limbs flopping. A joint's rotation limits are its stops, so a head can nod and never spin.
What else is in there?
Most of it predates version 4, so here is the short version for anyone who arrives at 4.
- Draw. A Bézier pen, 43 pressure-sensitive brushes, and a watercolour that bleeds, granulates and dries on its own.
- Morph. One shape becomes another, keyframed like anything else.
- Type. Kinetic text looks previewed as the real animation, a sound per glyph, text on a path, and right-to-left and Arabic shaping that actually shapes.
- Edit. A multi-track timeline with trims, ripples, transitions, speed ramps and nested comps. Groups behave like clips.
- Effects. 36 stackable, keyframeable effects: glow, lightning, glitch, liquid glass, halftone, film grain, and a colour page with node graphs.
- Libraries. 337,000 open-source icons from 208 licence-checked sets, each of which can draw itself on, and 4,555 CC0 sound effects.
- Ship. MP4, WebM, GIF, PNG sequences, PDF, SVG, and Lottie with a fidelity report.
Morph: pentagon, heart, flower. Same layer, keyframed geometry.
One logo, five effects from the stack: glow, boil, lightning, pixelate, glitch.
If you are wondering whether it does a specific thing, ask the list. It is the same capability index as the landing page, so it can't promise anything the page doesn't.
Does it do the thing you need? The whole list, searchable, is on the blog version and on atomcut.net.
Who drew the film?
Claude did, through MCP. AtomCut exposes every command in the app to agents, so a chat model, or Claude Code in a terminal, can create layers, key them, run physics, render a frame and look at it. The launch film for version 4 was built that way, one generator script per scene. The small orange tool-call lines in the film's captions are the real calls that made the scene beneath them.
That leaves three ways to make something in it:
- By hand. Draw it, key it, scrub it.
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By script. Version 4.2 added a Scripts panel where
await ac.layer.create({…})runs against your project and saves with it. A button copies a briefing for a chatbot (your comps, your media, every command, the real property names), so you can ask any model for a script, paste its answer, run it, and paste the error back. Run a file again and it replaces what it made last time. This part is in the free editor. - By agent. The built-in agent, or Claude Code and other MCP clients, can run the commands directly, render a frame, look at it and fix it. That is the Pro part.
AtomCut's 3D is a space for motion graphics: titles with depth, objects with physics, camera moves, a scene that composes with your 2D. It is not a Blender replacement: there is no sculpting and no path-traced rendering, and if you need those, Blender is the right tool.
It also runs in a browser, so it has a browser's limits. A heavy 4K timeline will be slower than it would be in a native editor, and a world with particles and motion blur gets a time budget per frame instead of unlimited samples. A browser can also switch off 3D for a tab; AtomCut says so once and puts a Reload button where the world was, instead of flooding the console.
Particles are the gap that stung us while making the film. The 3D
particlesandexplodemodifiers exist and carry a Big Bang well, but there is no 2D emitter in a flat comp, no confetti or sparks preset, and particles don't collide with bodies yet. It's on the roadmap, with no date.
What does it cost?
Free: every tool, effect and panel, unlimited projects saved on your machine, no watermark, video export up to 720p. Pro is $29 a year with a seven-day trial, or $59 once for the first 300 buyers, and adds full HD and 4K export, transparent and per-layer export, and the AI agent.
Open the studio: app.atomcut.net
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