The Seamless Pattern Maker is 100% client-side. Your design is represented as a small typed spec — a motif kind, a repeat mode, a cell size, colours, scale, rotation and scatter values plus a seed — that a pure, framework-free engine turns into a resolved repeat unit. That unit drives the live preview, is rasterised to PNG on an in-memory <canvas>, and is serialised to a standalone SVG string; none of these steps contact a network. There is no upload endpoint, no server-side rendering, no external stock-imagery library and no AI generator in the loop — the motifs are drawn from code, not fetched. The tool works offline once cached, keeps no accounts, sets no tracking, and discards everything the moment you close the tab.

Seamlessness is guaranteed by construction, following the standard rule from SVG-pattern and textile practice: a repeat is seamless only if every mark crossing a tile edge also appears, clipped identically, on the opposite edge — and every corner-crossing mark appears at all four corners. Rather than clipping shapes at draw time (which is error-prone), the engine emits up to nine copies of each motif — the tile plus its eight neighbours, offset by (±width, ±height). Because the paint that overflows one edge is drawn again on the other side, the tile lines up perfectly with a copy of itself. You can verify this yourself: the “Tiled surface” preview paints the repeat unit edge-to-edge, so any seam would be obvious — and there is none. The “Repeat unit” view outlines a single tile so you can see the minimal building block.

SVG is a vector format, so it stays razor-sharp from a small thumbnail to a large-format print and re-tiles infinitely — it is the best master to keep. PNG is a fixed-resolution raster: convenient because it drops straight into apps that don’t accept SVG, but it looks crisp only at and below its export size and softens if scaled far beyond it, so choose a larger box (1024–2048px) for print or high-DPI screens. The PNG (surface) export is deliberately rounded to a whole number of tiles so the exported image itself re-tiles seamlessly, and PNG (1 tile) gives you the single repeat unit for a CSS background-image. As for the tile size: a straight grid repeats every one cell, but a brick (running-bond) repeat offsets alternate rows by half, a half-drop drops alternate columns by half, and a hexagonal repeat uses a √3-based offset — each needs a 2× tile in one axis before the offset pattern lines back up, which is why the repeat unit can be twice as tall or wide as a single cell.

By design this is a geometric pattern editor: it composes tiles from a fixed set of code-drawn motifs (dots, rings, polygons, stars, hearts, leaves, waves and lines) rather than tracing, cutting out or “making seamless” an uploaded photo or texture — deliberately, so no image needs to leave your browser and no external service is involved. It is also not an AI generator: there is no model inventing a motif for you. The honest trade-off is that originality comes from how you combine motif, repeat mode, colours, scale, rotation and scatter, plus the deterministic Shuffle that re-randomises the layout while keeping it seamless. If you specifically need to convert a scanned fabric or photograph into a repeat, that is a different (image-based) workflow this tool intentionally does not perform.