Why did the water in my photo get replaced too?

Because the automatic step guesses from colour and position. Lakes and sea reflect the sky, so the colour is near-identical, and «higher up is more likely sky» is a weighting rather than a hard cut-off — water in the middle of the frame can still cross the line. That's not a fault, it's the price of a simple rule. The fix: Alt-click a few times on the water — the wand removes the connected region, and two or three clicks usually clears it.

Does this count as AI?

No, and we won't call it that. A real segmentation model downloads tens of megabytes and then runs inference; this is a few dozen lines of colour-and-position rules that produce a result the moment the page opens, entirely offline. It genuinely is less accurate than a model, and our answer to that is to make manual correction quick (four selection tools, Alt-subtract, click-to-delete on the result) rather than to rename it into something grander.

The ground light doesn't match the new sky and it looks fake. What now?

That's the real ceiling of sky replacement: we swap the pixels of the sky region only and don't relight the foreground to match. Flat overcast light under a golden sunset reads wrong at a glance. The practical answers are to pick a sky of similar tone (pale blue for overcast, dusk for early morning), or to hit «Pro» afterwards and nudge the ground towards the sky's colour temperature with curves or colour balance.

Is my photo uploaded?

No. Decoding, selection and compositing all happen in your browser — you can check it yourself: open the Network panel in developer tools, and from drop to result no request carries the image's contents. The sky image you supply isn't uploaded either.

Sky replacement: swap a flat grey sky for blue or sunset, and fix the edges yourself

Shot on an overcast day, the sky comes out a flat white. Swap it — and keep the say over the edges.

or start a blank document

The usual disappointment with holiday photos is the sky not playing along: good scene, good people, and a dead white slab overhead that drains the whole picture. Swapping the sky isn't the hard part — the boundary is. Treetops, eaves and distant ridges have ragged outlines, and one clean cut through them looks fake. This page splits the job into «which area» and «what to put there», and lets you change both.

About that automatic step: it judges by colour plus position — bluish, or bright and unsaturated — weighted by «the higher up, the more likely it's sky». That's a few dozen lines of ordinary code, not an AI model. The upside is it works the instant the page opens, downloads nothing and runs offline. The cost is that it gets things wrong: lakes, blue glass façades, white walls, snow and pale clothing can all read as sky. Which is why the manual tools here aren't a fallback — they're part of the normal flow.

Key features

Four preset skies, one click each

Blue, sunset, dusk, night — each a vertical gradient, darker at the zenith and lighter towards the horizon, the way real skies fall. Click one and the right pane changes immediately.

Or use a sky photo of your own

Hit «Use my image» and pick one. It's centred and cropped to cover rather than stretched — drop a 16:9 sunset into a portrait shot and the clouds won't be pulled into noodles.

Wrong area? Fix it there and then, four ways

Magic wand adds a patch per click, quick select paints continuously, the rectangle grabs a block, and Alt-click subtracts. You can also click straight on the result to delete a piece. Ctrl+Z undoes that one action, not the whole session.

Feather up to 40 controls how soft the seam is

A cutout edge only needs 1–2px to stop looking jagged, but the line where sky meets land — treetops, roof ridges, far hills — is a gradient to begin with. Too little feather leaves a hard outline. The range here goes to 40, matching the editor's own dialog.

How to use

1
Drop a photo in

Drag, click to pick, or paste with Ctrl+V. The sky is outlined automatically and the right pane already shows it replaced.
2
Check what got selected

The header tells you what percentage is selected. If water or a white wall came along, Alt-click there to subtract it.
3
Pick a sky, or supply your own

Click through the four presets to compare; if none fits, use your own image. Every click recomputes the result — there is no second «apply» button.
4
Set the feather, then download

Hard seam? Raise the feather. The export is JPG — after a sky swap the whole frame is opaque, so PNG would just double the size for nothing. To keep working on it, «Pro» carries the current result into the editor.

FAQ

Why did the water in my photo get replaced too?: Because the automatic step guesses from colour and position. Lakes and sea reflect the sky, so the colour is near-identical, and «higher up is more likely sky» is a weighting rather than a hard cut-off — water in the middle of the frame can still cross the line. That's not a fault, it's the price of a simple rule. The fix: Alt-click a few times on the water — the wand removes the connected region, and two or three clicks usually clears it.
Does this count as AI?: No, and we won't call it that. A real segmentation model downloads tens of megabytes and then runs inference; this is a few dozen lines of colour-and-position rules that produce a result the moment the page opens, entirely offline. It genuinely is less accurate than a model, and our answer to that is to make manual correction quick (four selection tools, Alt-subtract, click-to-delete on the result) rather than to rename it into something grander.
The ground light doesn't match the new sky and it looks fake. What now?: That's the real ceiling of sky replacement: we swap the pixels of the sky region only and don't relight the foreground to match. Flat overcast light under a golden sunset reads wrong at a glance. The practical answers are to pick a sky of similar tone (pale blue for overcast, dusk for early morning), or to hit «Pro» afterwards and nudge the ground towards the sky's colour temperature with curves or colour balance.
Is my photo uploaded?: No. Decoding, selection and compositing all happen in your browser — you can check it yourself: open the Network panel in developer tools, and from drop to result no request carries the image's contents. The sky image you supply isn't uploaded either.

Try Sky replacement: swap a flat grey sky for blue or sunset, and fix the edges yourself now

Runs fully in your browser · no install · no signup · images never uploaded