True-to-device viewports
Pages render at each device's exact width, so layouts wrap, break and reflow exactly as they do in real life — with live pixel readouts.
Responsive viewport tester · iPhone & iPadResponsive viewport tester for iPhone & iPad
Every device size.
Every device size.
On the go.
Open any URL at true iPhone, iPad and Mac viewports — straight from your iPhone or iPad, wherever you are. Real layouts at real widths, not a scaled screenshot.
More info
Coming soon
A paid, one-time purchase. No accounts, no subscriptions, no tracking.
Tap a device — the page reflows at that exact width, just like in the app. ← → to switch.
Built for developers
Type a URL. Pick a device. Done.
Everything you need to check a layout across every screen — without a laptop in reach.
Every device, one tap
iPhone SE through 17 Pro Max, iPad mini to Pro 13", and six Macs from MacBook to iMac 24" — presets ready to go.
Side-by-side multi-view
On iPad in landscape, place phone, tablet and desktop next to each other. Every pane loads the same URL — configure each independently.
Pinch, zoom & rotate
Crisp pinch-to-zoom, exactly like a real browser. Flip any device between portrait and landscape to test both ways.
Localhost, LAN & Tailscale
Point ViewPortal at localhost or a 192.168.x.x dev server — or reach your always-on home Mac from anywhere over Tailscale. Catch breakpoint bugs before you ship, wherever you are.
Private by design
No accounts, no analytics, no tracking. URLs, favourites and preferences stay on your device and are never transmitted.
iPad multi-view
Phone, tablet and desktop — at once.
The hero feature. On iPad in landscape, line up every screen size side by side and watch the same page render at three true widths simultaneously.
- One URL, three viewports. Compare breakpoints in a single glance.
- Configure each pane independently. Different devices, your choice.
- Focus or go fullscreen on any pane for a closer look.
On your iPhone
The whole web, at desktop size — in your pocket.
Coding from your iPhone? Confirm a desktop layout, reproduce a bug report, or check an AI agent's change at true device widths — no laptop required.
- Live pixel-size readouts show exactly what you're testing.
- Realistic device framing keeps the focus on your layout at its true width.
- Favourites & recents keep the sites you test most a tap away.
How it works
Real viewports, not screenshots.
ViewPortal loads any URL in a real browser engine and forces the page's layout viewport to each device's exact width — so media queries and breakpoints fire correctly. What you see is what your visitors get.
1 · Type a URL
Any public site, or your own localhost / LAN dev server.
2 · Pick a device
Choose from iPhone, iPad and Mac presets — and rotate to taste.
3 · See it for real
The page reflows at the true width, with the exact pixel size shown.
Why I built it
I'm increasingly coding from my phone — prompting AI agents to make changes while I'm on the go.
I kept wanting to check how a desktop-sized layout looked, confirm an agent's change was right, or reproduce a bug report across every device size — without a laptop in reach.
ViewPortal is the tool I wanted: open any URL and see it at true iPhone, iPad and Mac viewports, straight from your iPhone.
Reece · maker of ViewPortal
Questions
Good to know
Is ViewPortal a web browser?
No — it's a responsive-design testing tool for developers. It uses the same web engine as Safari (WKWebView), but its whole job is to render pages at true device viewport sizes, with device chrome, pixel readouts and multi-view, rather than to browse.
Does it really render at true device sizes?
Yes. It forces the page's layout viewport to each preset's exact width, so the page renders at its real
innerWidth and media queries fire correctly — not a scaled-down screenshot. The live readout shows the precise pixel dimensions you're testing.Can I preview localhost or a LAN dev server?
Yes. Point ViewPortal at
localhost or a 192.168.x.x address to preview work in progress and catch breakpoint bugs before you ship. Local network access is requested only for previewing your own dev servers.Do you collect any data?
No. There are no accounts, no analytics and no tracking. The web addresses you enter, your favourites and your preferences are stored only on your device and are never transmitted. See the privacy policy for details.
Does it work on both iPhone and iPad?
Yes — it's a universal app for iPhone and iPad. Side-by-side multi-view (phone + tablet + desktop at once) appears on iPad, or on iPhone in landscape, where there's room to show every screen together.
Responsive testing, wherever you are.
ViewPortal is coming soon to the App Store for iPhone and iPad. A paid, one-time purchase — no accounts, no subscriptions, no tracking.
Coming soon to the App Store