Kerf vs. Polypane.
Both tools bridge design and development. They solve different problems. The right pick depends on where you spend your day — shipping a codebase, or testing a design across every device size.
At a glance
Both Kerf and Polypane offer:
- Live style tweaking — change CSS and see it immediately as you work.
- Accessibility checks — catch contrast and hierarchy issues as you work (Pro in Kerf).
- Live preview — see changes as you make them.
Kerf is better for
- Working on your source files. Kerf is a file-aware editor, not a browser.
It opens your local folder and writes directly to your
.cssand.htmlfiles. - Shipping. Kerf Pro includes one-click Vercel deploy. You go from local folder to live URL without touching a CLI or Git.
- System maintenance. Kerf scans your CSS for repeated values and consolidates them into design tokens.
- Lower price. Kerf's core editor is free; Pro is $96/year or $10/mo. If you'd rather not pay browser-tool prices for an editor, Kerf is the clearer choice.
Polypane is better for
- Responsive testing. Polypane sets the bar here. It shows your site across many synchronized viewports at once. If your primary task is ensuring a design works across every device size, Polypane is the category leader.
- Browser-first workflows. Polypane is a specialized browser. It shows how your site behaves in the wild — social previews, interaction testing, layout-shift debugging.
- Depth of audit. Polypane's debug toolkit — color-blindness simulators, layout-shift overlay, structured data preview — covers more ground than Kerf's focused five-check audit.
Feature comparison
| Feature | Kerf | Polypane |
|---|---|---|
| Works on your source files | Yes — HTML, CSS, new files | No — edits the live DOM, not your files |
| Multi-viewport sync | Single focus | Extensive, simultaneous |
| One-click Vercel deploy | Yes (Pro) | No |
| Design token consolidation | Yes (Pro) | No |
| Accessibility audit | Five-category audit (Pro) | Extensive |
| Platforms | macOS, Linux (Windows coming soon) | macOS, Windows, Linux |
Pricing
Kerf
- Free tier: full visual editor.
- Pro: $96/year or $10/mo.
- Pro adds Vercel deploy, design token consolidation, accessibility audit, and snippet library.
Polypane
- Individual: ~$13/mo annual, ~$19/mo monthly.
- No free tier — subscription only.
- Verify current pricing at polypane.app/pricing.
The honest answer
The choice is about your focus.
Pick Polypane if your day is dominated by responsive testing across devices. If you need an iPhone SE, an iPad, and a 4K monitor side by side, Polypane is worth the subscription.
Pick Kerf if you're a solo builder or design engineer moving from a messy first draft to a polished, tokenized, shipped product. If you want a tool that understands your files and deploys them to Vercel in one click, Kerf is built for you.