Seamly2D and Valentina are free, open source programs for drafting sewing patterns yourself on a computer: you build each pattern from points, lines and formulas, and it recalculates for any set of measurements. Sewly drafts the pattern for you from a photo or a description. If you want to learn and control the drafting, use Seamly2D or Valentina; if you want a pattern ready to sew tonight, use Sewly.

What are Seamly2D and Valentina?

Valentina was started in 2013 as open source pattern-making software. In 2017 the project split: one of its founders continued it as Seamly2D, while the original developer kept developing Valentina. Both are released under the GPLv3 license and run on Windows, macOS and Linux. At the time of writing (October 2026), both are actively developed. Seamly2D is free to download. Valentina's source code is free too, but its newest ready-to-install builds are offered to paying subscribers on its website, while older releases are free to download.

Both work the same way. You draft a pattern as you would on paper, following a drafting system, but every point is defined by a formula that refers to body measurements, such as a quarter of the bust plus a little ease. The result is a parametric pattern: load another person's measurement file and the whole pattern recalculates. You can also load multi-size tables to produce graded sizes. Finished pieces are laid out and exported as PDF, SVG, DXF or plotter files.

How is Sewly different?

Sewly also drafts from measurements, but you never see the formulas. You show it a garment (a photo, a screenshot, a Pinterest or Instagram link, or a description). The AI identifies the garment type and its details and sets the options; Sewly's drafting engine then draws every piece from flat-pattern blocks with your measurements and the right ease. Same inputs, same pattern, every time, and changing a measurement or an option redraws the pattern instantly, without the AI.

What you get is a sewable pattern rather than a drafting file: seam allowances included (1.5 cm or 5/8 in on wovens, 1 cm or 3/8 in on knits by default), a 3D preview on a mannequin built from your measurements, and a sewing guide with the steps for your version, the pieces list, notions, cutting layouts and fabric quantities. On paid plans you print it on A4, US Letter, A3, Tabloid, A0, 36 × 48 in or as a projector file.

Who should choose Seamly2D or Valentina?

  • People who want to learn drafting. Building a bodice block step by step in software teaches you why a pattern has the shape it has, and the formulas make the logic explicit.
  • Anyone who needs garments outside a library. Historical costume, tailored coats, corsetry, men's shirts with collar stands: if you can draft it, you can build it once and reuse it for every measurement set.
  • Small brands and pattern designers. Multi-size tables and DXF export suit grading and production work, and Seamly2D states that you can use, share and sell the patterns you make with it.
  • People who prefer open source desktop software and want their files on their own computer.

Who should choose Sewly?

  • People who want to sew, not draft. There is no drafting system to learn; you choose options such as length, neckline and sleeves instead of writing formulas.
  • People starting from a picture. Sewly reads the garment's silhouette and details from a photo or link and drafts the closest pattern.
  • Beginners. The sewing guide explains each step for your version, and you can ask it questions while you sew. Our sewing for beginners page shows where to start.
  • People who want to see before they cut. The 3D preview shows proportions on a body with your measurements.

What are the limits of each?

Seamly2D and Valentina have a real learning curve. You need to know a drafting method (from a book or a course), the interface is that of a CAD program, and there is no garment library, no 3D view and no sewing instructions: each pattern is as good as your drafting. Community forums and documentation help, but expect to invest real time before your first complete pattern.

Sewly is the opposite trade-off. It is fast and needs no drafting knowledge, but you are limited to the garment types it knows (20 at launch: skirts, dresses, tops, sweatshirts, pull-on trousers and shorts, a kimono jacket, bags, a hat and home pieces) and their options. You cannot open the formulas and redesign a block, it exports print-ready PDFs rather than CAD files, and it does not yet draft tailored jackets, coats, fly-front jeans, shirts with collar stands, lingerie or swimwear. Printing needs a paid plan, from $7.99 a month or $59 a year.

Can you use both?

Yes. You can use Sewly for everyday garments and Seamly2D or Valentina for the projects Sewly does not cover. If you are learning to draft, a Sewly pattern drafted to your measurements is also a useful reference to compare with your own block: if your bodice and Sewly's differ a lot at the bust or the shoulder, it is worth checking your measurements and your formulas. Our article on how Sewly drafts a pattern explains the blocks and ease it uses.