Does this rename duplicate IDs?

No. This tool reports duplicates. A rename ID tool is planned separately.

Does it check IDs across multiple files?

The first version checks the pasted SVG only.

Can duplicate IDs break gradients?

Yes. Gradients, masks, clips, and symbols can resolve to the wrong element when IDs collide.

Is Duplicate ID Checker free?

Yes. SVGKit tools are free to use with no account required.

Does Duplicate ID Checker upload my files?

No. The tool runs entirely in your browser, so your files never leave your device.

Which standards does it check against?

The SVG specification plus the specific rules this tool focuses on. Findings reference the rule so you can judge each one.

Does it fix problems automatically?

No. Validation reports findings; the edit and optimize tools apply the fixes.

Can it produce false positives?

Rarely. When a finding does not apply to your context, note it and move on — the tool cannot see how the SVG is consumed.

SVGKit

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Duplicate ID Checker

Validate

Find duplicate SVG id values that can break gradients, masks, clips, sprites, and inline embeds.

Duplicate ID Checker

Find duplicate SVG id values that can break gradients, masks, clips, sprites, and inline embeds.

Result

Choose an SVG file, paste SVG markup, or load the sample to begin.

Page context

Where Duplicate ID Checker fits

Duplicate ID Checker finds repeated SVG id values that can break gradients, masks, clips, symbols, and inline embeds.

Related guides

SVG security checklist for untrusted files

Why duplicate IDs matter

SVG references use id values for defs, masks, clipPaths, gradients, symbols, and use elements. Duplicate IDs make references ambiguous, especially when multiple SVGs are inlined on one page.

Report format

The checker lists unique ID counts, duplicate values, and a JSON report with counts for each detected ID.

Duplicate ID Checker reports findings with severity and context — fix hard failures first, then re-run for a clean report.

What gets checked

Duplicate ID Checker parses the document locally and validates it against structural rules and this tool's focus area, reporting each finding with enough context to locate it.

Common findings and fixes

Typical issues include missing viewBox attributes, duplicate IDs, unsafe active content, and deprecated structures. Most have a direct fix in the matching edit or optimize tools.

Severity and manual review

Parse errors and unsafe content are hard failures; style-level findings need judgment based on where the SVG ships. Automated checks complement, not replace, a visual review.

Privacy

Validation runs locally in your browser. Files are parsed in the page and never uploaded.

How to use

Paste SVG. Paste SVG markup with defs or reusable IDs.
Review duplicates. Check duplicate ID values and counts.
Fix source. Rename duplicate IDs in the SVG or run a future rename tool.

Frequently asked questions

Does this rename duplicate IDs?: No. This tool reports duplicates. A rename ID tool is planned separately.
Does it check IDs across multiple files?: The first version checks the pasted SVG only.
Can duplicate IDs break gradients?: Yes. Gradients, masks, clips, and symbols can resolve to the wrong element when IDs collide.
Is Duplicate ID Checker free?: Yes. SVGKit tools are free to use with no account required.
Does Duplicate ID Checker upload my files?: No. The tool runs entirely in your browser, so your files never leave your device.
Which standards does it check against?: The SVG specification plus the specific rules this tool focuses on. Findings reference the rule so you can judge each one.
Does it fix problems automatically?: No. Validation reports findings; the edit and optimize tools apply the fixes.
Can it produce false positives?: Rarely. When a finding does not apply to your context, note it and move on — the tool cannot see how the SVG is consumed.