How to Green-Screen a Video Free (Chroma Key in Your Browser)

You can key out a green screen in a browser tab, free, with nothing installed. ClipCraft's VideoCraft is a free green screen video editor in the plain sense: put a background clip on track V1, your green-screen footage on V2, drop the Ultra Key effect on it, and the Player shows the composite live while you tune the matte. The keyer runs on your GPU through WebGL, so the frame updates live as you drag a slider. Here's the whole workflow, including the two steps most tutorials skip: checking your matte in the Alpha view and getting rid of green spill.

Keying is a stacking trick, so stack first

A chroma keyer doesn't replace your background. It punches transparency into the clip wherever it sees the key color, and whatever sits on the track below shows through the hole. That means the setup comes before the effect:

1. Create a free account and open VideoCraft. The editor is free for everyone, no watermark.
2. Drag your background clip (or a still image) straight onto the V1 lane of the timeline. Files dropped on a lane import and land as clips in one move.
3. Drag the green-screen clip onto V2, directly above it.

The editor opens with two video tracks ready, so there's nothing to add for a basic key. If you park the playhead over both clips now, you'll see only the green-screen footage, because V2 sits on top and is still fully opaque. Good. That's what we're about to fix.

Apply Ultra Key and eyedrop the green

Open the Effects panel and type "green screen" into the search box. The keyword search knows what you mean and surfaces the Keying category. VideoCraft ships three keyers: Ultra Key (the full-featured one, modeled on Premiere's), Color Key (a simpler pick-a-color keyer), and Luma Key (keys by brightness). Use Ultra Key. Drag its tile onto the green clip in the timeline, or select the clip and double-click the tile.

Now the important part. In Clip Settings, the Ultra Key section starts with a Key Color swatch, and it defaults to pure green (#00ff00). Real footage is almost never that exact shade; my test clip's screen is #00b140, the standard chroma green, and studio screens drift further with lighting. So before touching any slider, click the little eyedropper next to the swatch and click the green right on the Player. One click and most of the background vanishes. (The eyedropper uses Chrome's EyeDropper API, so you'll see it in Chromium browsers; elsewhere you can still set the color with the swatch.)

Check the matte in the Alpha view

A key that looks fine on one frame can be quietly chewing holes in your subject. The composite view hides this, which is why Ultra Key has an Output dropdown at the top with three modes: Composite, Alpha Channel, and Color Channel. Switch to Alpha Channel and you get the matte itself. White is solid, black is transparent, and gray is trouble.

Scrub the whole clip in this view rather than judging a single frame. If the background isn't solid black, or your subject shows gray speckle, work the Matte Generation sliders: Transparency (defaults to 45%), Highlight, Shadow, Tolerance, and Pedestal. Raising Pedestal from its 10% default is my usual first move against a noisy background. Then move down to Matte Cleanup: Choke shrinks the matte edge inward to swallow green fringe, and Soften blurs the edge slightly so the cutout doesn't look like a sticker. Both start at 0, and a little goes a long way. Under the hood Choke is a matte-curve erode and Soften a small matte blur, lighter than Premiere's implementations, but on decent footage the result reads the same.

Kill the green spill

Once the matte is clean you'll often notice your subject still looks a bit radioactive around the hair and shoulders. That's spill: green light bouncing off the screen onto the subject. The matte can't fix it because the pixels are opaque; they're just tinted. Ultra Key's Spill Suppression group handles it with Desaturate (defaults to 25%), Range, Spill, and Luma controls. Push Desaturate and Spill up until the green rim dies, and stop before skin tones go gray.

There's also a Color Correction group at the bottom (saturation, hue, luminance) for nudging the foreground toward the background's color mood, so the composite feels lit by the same scene. And because every numeric parameter has a stopwatch, you can keyframe the key itself. A screen that darkens over the shot can get a Tolerance ramp instead of one compromise setting.

When Luma Key is the right tool

Not every background is green. A lot of AI-generated elements (smoke, fire, light leaks, particle loops) come on plain black, and plenty of stock overlays come on white. Chroma keying those fails badly because the subject usually contains the same neutral tones. Luma Key keys by brightness instead: a Threshold slider decides how dark counts as transparent, Softness feathers the cut, and Invert flips it for white backgrounds. For a fire clip on black, Luma Key plus the Screen blend mode in the Opacity section is usually all you need. I covered the layer side of this in the guide to editing AI-generated video.

Shooting tips that beat any slider

• Light the screen evenly. Two soft lights on the screen itself, separate from the subject's light, remove the shadows and hot spots that force Tolerance up.
• Move the subject away from the screen. Six feet or more, if the room allows. Distance is the cheapest spill suppression there is.
• Skip green and reflective clothing. Glasses and glossy jackets pick up spill.
• Feed the keyer your best-quality file. Compression smears the color detail along edges, and the keyer works exactly where compression hurts most. Key the original camera file, never a re-upload.

What a free green screen video editor covers today

Everything above happens in the free editor. There's no keying paywall and no watermark; paid planssell storage and server compute, not features. If you're weighing options first, I compared the browser editors honestly in the best free online video editors roundup, and the full VideoCraft walkthrough covers the rest of the editor beyond keying.

Green screen has a reputation as the fiddly part of video editing, and it earns it when you skip the matte check. Eyedrop the actual green, confirm the Alpha view is clean across the whole clip, then handle the spill. In that order, most footage keys in a couple of minutes.