Smooth curves

Even out the curvature along a path with a live preview, without letting it drift further than a distance you set.

What smooth curves does

Smooth curves relaxes the curve handles along a path so its curvature flows instead of kinking at every anchor. It works on the path you already have: it never adds or removes anchors, and no point of the result moves further from the original than the deviation you allow, so the shape you drew is still the shape you get.

It solves the opposite half of the problem from Simplify vector. Simplify removes anchors you don't need; smooth keeps every anchor and fixes the way the segments meet.

Smoothing a path

Select one or more vector layers on the canvas. To smooth only part of a path, enter vector edit mode first and select the anchors or segments you want to change.
In the contextual toolbar at the bottom of the canvas, open the Path editing menu and choose Smooth curves.
The toolbar becomes the Smooth curves settings bar and the canvas shows a live preview.
Adjust the settings — the preview follows every change.
Click ✓ or press Enter to commit. Click ✕ or press Esc to leave the path exactly as it was.

With anchors or segments selected in vector edit mode, only those segments change and the rest of the path is left alone. With nothing selected inside the path, the whole path is smoothed.

Settings

Setting	What it does
Keep anchors / Optimize contour	Keep anchors (the default) moves only the curve handles, so every anchor stays exactly where you put it. Optimize contour also lets anchors slide along, which smooths more but moves the points.
Strength	0 to 100 (default 50). How hard the smoothing pulls. At 0 nothing changes.
Max deviation	How far the path may move, in document pixels (default 0.25, up to 1000). No point of the result travels further than this from the original, and zooming does not change it. At 0 nothing changes.
Keep sharp corners	On by default. An anchor where the two segments genuinely meet at a corner keeps its point. Turn it off to pull those corners into the flow of the curve.

What smoothing never changes

Rounded corners. An anchor rounded with a corner radius or the Corner tool, and the segments on either side of it, are left alone, so smoothing can never eat a radius you set.
The path's topology. A preview that would make the path cross itself where it did not before is rejected, and the path stays as it was.
Paint. Fills, strokes, variable stroke widths and the anchor radii you set travel with the smoothed geometry.

Things to know

Applying a change to a shape (rectangle, ellipse, polygon, star) turns that layer into a vector path, so the parametric shape controls are gone afterwards. A shape the smoothing left alone stays a shape.
Applying the whole selection is one undo step. When nothing changed — strength or max deviation at 0, or every candidate rejected — nothing is committed and there is no undo entry.
While the session is open it owns the keyboard, the same as the other path tools: Enter applies and Esc cancels, and the vector edit shortcuts stand down until you leave.
Changing the selection, or an edit arriving from a collaborator, closes the session and leaves the path unchanged.
A corner setting is stored by position, so two anchors sitting exactly on top of each other share one: rounding either of them protects both.
The preview is recomputed as you drag a slider. On a very detailed path — thousands of curve segments — each change takes a moment (roughly 0.15 s at 1,000 segments, 0.8 s at 5,000). Selecting the segments you care about in vector edit mode keeps it responsive.

Tips

Start with Keep anchors. Reach for Optimize contour only when the anchors themselves are in awkward places, and expect the points to move.
Raise Max deviation rather than Strength when the result is still bumpy: strength is how hard it pulls, deviation is how far it is allowed to get.
Trace, then simplify, then smooth. Removing the redundant anchors first gives the smoothing far less to fight.