SVG Optimizer — Free SVG Minifier (In-Browser)

An exported SVG is mostly editor bookkeeping

Export from a design tool and the file contains far more than the shapes. Layer and group names, generator comments, an XML declaration, unused definitions, hidden elements, and coordinates carried to more decimal places than any screen can resolve.

None of it renders. And it is not carelessness on the design tool's part — it is preserving editability, which is exactly what you want right up until the file ships and never again after.

What this does

It runs SVGO in your browser. Paste markup or drop a .svg, and three options are available, all on by default: multipass, which repeats the optimisation until it stops improving; remove comments; and remove metadata. It reports the original size, the optimised size and the saving, with a preview so you can see the result before copying or downloading.

The three things that look like bloat and are not

This is the section worth reading before you optimise anything important, because each of these breaks a file that will still look fine in a preview thumbnail.

• The viewBox attribute. It declares the coordinate space the drawing occupies — viewBox="0 0 1200 800" means the artwork fits a 1200 by 800 area — and it is what lets the browser scale the graphic to any container. Remove it and the SVG falls back to fixed dimensions, losing the one property that made it worth choosing over a PNG. This is the classic destructive optimisation.
• IDs that something else references. An optimiser sees only this file. It cannot know that an element's ID is targeted by a CSS rule in your stylesheet, by a line of JavaScript, or by a use element elsewhere. Unreferenced within the file and unreferenced anywhere look identical to it. Worth knowing that this tool does not expose an ID toggle, so if your graphic is animated or scripted, check the output against its real context rather than assuming.
• Coordinate rounding. Most of the saving comes from here, and pushed far enough it visibly distorts curves and opens hairline gaps between shapes that were meant to meet.

Hence the rule: look at the optimised file rendered at the size you will actually use it, next to the original, before shipping. A logo that has lost its viewBox looks perfectly correct in a preview pane and wrong everywhere else.

Where SVG belongs

Logos, icons, diagrams, charts — anything built from shapes that must stay sharp at any size, because it stores instructions rather than pixels and simply redraws larger.

Not photographs. Auto-tracing a photo produces thousands of stacked shapes, giving a file far heavier than the JPEG it came from and a picture that looks worse. If the source is a photograph, it stays a raster format.

One security note

SVG is markup, so a file can legitimately contain a script element. That is a reason to be careful about SVGs other people upload to your site and you render inline — not a reason to avoid the format for your own artwork, where you control what is in the file.

Everything runs in your browser; nothing is uploaded. For raster formats, where the file stores pixels rather than drawing instructions, use the image optimizer instead.