Remove unused defs (`removeUselessDefs`)

Removes unreferenced items in <defs> (gradients, symbols, paths) after other cleanup passes.

What Remove unused defs does in SVGO

SVGO applies removeUselessDefs as part of its plugin pipeline. On SVGOMG.net the toggle is labeled Remove unused defs (enabled by default). Optimization runs entirely in your browser — files are not uploaded to a server.

Use SVGOMG.net with Show original to compare before and after. If output looks wrong, disable this plugin first, then re-enable related transforms one at a time.

When to enable

Default; defs bloat is common in design-tool exports.

When to disable

When defs are referenced dynamically at runtime in ways SVGO cannot see.

Watch out for

Run after path and ID cleanup for accurate reference tracking.

Try it

Open SVGOMG.net and load your SVG (file, paste, or demo).
Find Remove unused defs in the Features panel (removeUselessDefs).
Toggle the plugin and compare the preview; download when satisfied.

Part of: IDs, defs, and references

This plugin is covered in the IDs, defs, and references topic guide along with related transforms.

SVGO Plugin Guide

Browse the SVGO Plugin Guide or read the full SVG optimization walkthrough.