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SafariHow they compare
CSSPeeper is a beautiful read-only inspector. Design Mode covers the read use case and adds editing, persistence, exports, and MCP.
Feature-by-feature
| Feature | Design Mode | CSSPeeper |
|---|---|---|
| Visual editing on a scriptable webpage | Yes — typography, colour, layout, spacing, motion and effects on localhost, staging or production pages the extension can script. Browser-protected pages are excluded. | Read-only |
| MCP (Model Context Protocol) handoff to AI agents | Yes — Cloud, Local, and Self-hosted modes; eight common session tools, plus Local feedback rounds | No |
| Persistent change history (Changes tab) | Yes — searchable, filterable, exportable | None |
| Open source | Yes (MIT) | Proprietary |
| Price | Free MIT-licensed extension | Free |
| Markdown / JSON export of the diff | Yes | Copy CSS |
| Best fit for | Designers, developers, QA, PMs, content, indie hackers, agencies, vibe coders | Learning, inspecting |
When to pick Design Mode
- You want to change values, not just read them.
- You want to ship structured edits to engineering or an AI agent.
When to pick CSSPeeper
- You purely want to learn how a page is built.
Honest take
Different tools for different tasks. CSSPeeper is a wonderful learning aid; Design Mode is a working surface.