The browser for web developers
One browser for the whole job
of building the web.
Sizzy is a desktop browser made for web developers. Your projects, every device, every login state, the console, an API client, terminals and coding agents all live in one window, so you stop juggling tabs, windows and tools.
14-day free trial · No credit card · macOS, Windows and Linux
Scroll and clicks stay in sync across every device
- 12:04:01MacBook Aircheckout: hydrated in 212 ms
- 12:04:01iPhone 17 Procart → 2 items · SPRING20 applied
- 12:04:02iPad Pro 11"hero.png is 1.8 MB; larger than the 500 KB budget
- 12:04:02iPhone 17 ProTypeError: Cannot read properties of undefined (reading 'coupon')
Interactive sketch of the Sizzy window. Hover to pause, click the panel tabs to explore.
What's inside
Everything that used to be five apps and a pile of tabs.
Sizzy is built on Chromium, so the web looks the way it will for your users. Around the page it adds the things a developer actually needs while building.
Project workspaces
Each project keeps its URLs, devices, sessions, notes, snippets and terminals. Switch projects, not windows.
See how it works →Every device on one canvas
Real device sizes side by side. Scrolling, clicks, typing and navigation stay in sync while you work.
See how it works →Sessions for every user
Isolated cookies, cache and storage per session. Be the admin, the customer and a stranger at the same time.
See how it works →A debugging panel, not just DevTools
One console for all devices, docked Chromium DevTools, storage and CSS editors, request headers and an API client.
See how it works →Screenshots and Photo Studio
Capture one device, all of them, the full page or with a frame. Compose mockups and record video or GIF.
See how it works →Terminals and coding agents
Run your dev command, open terminals and hand tasks to Claude Code or Codex without leaving the page you are testing.
See how it works →
Projects
Open a project and the whole setup comes back.
A Sizzy project is more than a bookmark. It knows where the code lives, how to start it, which devices and sessions you test with, and what happened to it recently.
Knows the repo
Path on disk, dev command, package manager, Node version and your editor of choice. Open it in the editor or file manager from the switcher.
Remembers the workspace
Device presets, layout, per-project sessions and workspace tabs restore exactly as you left them.
Keeps the small stuff
Bookmarks, todos, notes and code snippets live in the debugging panel next to the page instead of in another app.
Shows what happened
A timeline of recent commits, deployments and process runs, with GitHub, Vercel and Coolify integrations for status.
- Node
- 22.11 · fnm
- Package manager
- pnpm
- Editor
- Cursor
- Device preset
- iPhone 17 Pro · iPad Pro · MacBook Air
- Deployed to Vercel · production2 min ago
- fix: coupon input overflow on phones9 min ago
- pnpm dev started1 h ago
Devices
Every screen size on one canvas, moving together.
Pick real devices with real viewports and user agents, arrange them the way you like, and interact once. Scroll, clicks, typing and navigation follow on every device until you turn sync off.
Simulations per device or for all
Flip conditions on one device or the whole canvas and see how the page copes.
- Network throttling
- Light / dark scheme
- Print stylesheet
- Locale
- Software keyboard
- JavaScript off
- Touch cursor
- Design mode
Modes for every kind of work
- Responsive shows all devices with horizontal, vertical, float and center align modes and per-device zoom.
- Focus gives one device the whole window. Full and Resizable turn Sizzy into a normal browser when that is what you need.
- Zen mode hides the chrome. Presets save a device set, layout and zoom so a whole setup is one click away.
- Device frames, minimal headers, custom devices and a QR code that opens the current URL on your real phone.
Sessions
Be the admin, the customer and a stranger at the same time.
A session is an isolated browser profile: its own cookies, cache and local storage. Assign one to each device and stop logging in and out to test what different users see.
Truly isolated
Each session is a separate storage partition, so an admin login on one device never leaks into the customer view on the next.
Per device, per project or global
Sessions can belong to a project or be shared across all of them. Pick a session from the device header or the URL bar.
Clean slate on demand
Clear one session's cache without touching the others when you need a first-visit experience again.
- AdminProject
- CustomerProject
- Fresh visitor
Debugging panel
Nineteen tabs of things you would otherwise open somewhere else.
The debugging panel docks under your devices, or floats in its own window. It starts with the Chromium DevTools you already know and keeps going.
- 12:04:01MacBook Aircheckout: hydrated in 212 ms
- 12:04:01iPhone 17 Procart → 2 items · SPRING20 applied
- 12:04:02iPad Pro 11"hero.png is 1.8 MB; larger than the 500 KB budget
- 12:04:02iPhone 17 ProTypeError: Cannot read properties of undefined (reading 'coupon')
- 12:04:03MacBook AirGET /api/cart 200 · 48 ms
Console. Logs from every device in one feed, filtered by device, level or text.
Universal inspect element
Point at anything on any device and jump straight to it in DevTools. Filter the console down to one device when it misbehaves.
Plugins that run inside the page
Grid overlay, debug styles, scroll to selector, page navigator, Google Fonts picker and a cache manager, all injected into every device.
Reference browser
Docs, issue trackers and design files open as normal tabs next to your devices, with search engines and pinned reference links per project.
Curious how the panel compares with plain DevTools device mode? Read the breakdown or browse the documentation.
Screenshots, video and Photo Studio
Proof that looks good enough to ship in the PR.
Screenshots that already know about device frames and scrolling pages. A studio for mockups. Video and GIF recording for the bug report or the launch tweet.
Drag the devices
From Butler or a shortcut
Screenshot all devices, all with frames, or all full-page from the command palette.
Video and GIF
Record one device from its menu or the whole studio, with pause, restart and a countdown so you can get into position.
Tuned full-page capture
Full-page screenshots are stitched from the scrolling page, with settings you can adjust when a layout trips up the capture.
Terminals and coding agents
Run the project and hand off the fix, right under the page.
Sizzy 74 added real terminals and coding agents to the debugging panel. You keep looking at the page on every device while the dev server, the tests and the agent work below it.
- dev
- test
- db
- new
~/code/storefront $ pnpm dev ▲ Next.js 16.2.9 - Local: http://localhost:3000 ✓ Ready in 812 ms ○ Compiling /checkout … ✓ Compiled /checkout in 212 ms GET /checkout 200 in 48 ms
iPhone 17 Pro screenshotThe coupon input overflows its card at 402px. Fix it without touching the desktop layout.
Found it. .coupon-row is a flex row and the input never got min-width: 0, so it keeps its intrinsic width. Plan: add min-w-0, let the row wrap under 420px, re-check on the iPhone and iPad.
Your CLI, your account
No separate AI subscription. Sizzy detects the installed Claude Code and Codex runtimes and shows whether each is ready.
Reusable agent roles
Define agents with a title, instructions, harness, default model and thinking level, then start sessions from any project.
Context from the page
Attach a device screenshot to a prompt, @-mention project files and hand over the project's own agent rules automatically.
MCP servers and skills
Toggle MCP servers and edit skills from inside Sizzy; queued prompts wait for the running turn to finish.
- Add SSO settings page
- Fix coupon overflow
- Dark mode contrast pass
- Migrate cart to server actions
Butler
A command palette that does the chores.
Press ⌘ ⇧ P and type. Butler runs every Sizzy action and a set of small tools you would otherwise open a terminal or a website for.
Workspace
- Add or remove devices
- Switch align mode, orientation and zoom
- Switch sessions and projects
- Open any debugging panel tab
- Jump to any settings tab
Utilities
- Kill a process on a port
- Local and public IP address
- Colour converter and calculator
- Encode, decode, bcrypt and UUID
- Search npm, caniuse and Font Awesome
Project
- Add a note or todo
- Search project files
- Navigate to a selector on the page
- Open the screenshots or videos folder
- Custom search engines with keywords
- Kill process on port 3000node · pid 48112↵
- Kill process on port 3001vite · pid 48210
Compared with your current browser
Chrome is for browsing. Sizzy is for building.
Sizzy runs the same Chromium engine, so nothing renders differently. It changes what surrounds the page.
| Capability | Sizzy | Chrome + DevTools |
|---|---|---|
| Chromium engine and DevTools | Yes | Yes |
| Several devices side by side in one window | Yes | No |
| Scroll, clicks, typing and navigation kept in sync | Yes | No |
| Isolated sessions per deviceChrome profiles are per window, not per viewport. | Yes | Partially |
| Project workspaces that restore devices, sessions and tabs | Yes | No |
| One console for every device | Yes | No |
| API client, storage editor, CSS overrides, request headersSpread across DevTools panels and extensions. | Yes | Partially |
| Screenshots of all devices, full-page and framedOne viewport at a time. | Yes | Partially |
| Terminals, processes and coding agents next to the page | Yes | No |
Weighing Sizzy against other developer browsers? Read the Polypane vs Sizzy vs Responsively comparison. It recommends trying both trials.
From developers
What people say after a week with it.
“If you aren't using @sizzyapp to test your web projects, you've goofed. This app saves me so much time manually resizing windows and toggling dev tool settings. Plus, synchronized scrolling is straight magic.”
Brian Lovin@brian_lovin “Just bought a lifetime license to @thekitze's sizzy.co because it seems like a MUCH better dev browser than Chrome/Brave/etc. for typical development. Especially looking forward to 'sessions' allowing me to easily be logged in as different users simultaneously.”
Kent C. Dodds@kentcdodds “Before @sizzyapp: damn, I forgot to test this on smaller screen sizes. *installed Sizzy* Now: wow, looks great on all screen sizes! Let's push this to production!”
Stefan Natter@natterstefan “I've been using @sizzyapp for the past couple of days and damn, it feels good. Writing CSS doesn't make my blood boil anymore and testing changes in Chrome feels like pounding nails with a screwdriver.”
Matt@veryspry
Pricing
One product. Pick how you want to pay for it.
Every plan unlocks all of Sizzy. Start with a 14-day free trial, no credit card required, and choose a plan only if it earned a place in your workflow.
Monthly
For a project, a contract or a busy month.
Billed monthly. Cancel any time.
Start free trialAnnual
Save 20% compared with monthly billing.
Billed $144 once a year.
Start free trialLifetime
For people who would rather never see another renewal.
One payment. Future updates included.
Get lifetime access- Every feature on every plan
- Projects, devices, sessions and the debugging panel
- Screenshots, Photo Studio and recording
- Terminals and coding agents
- macOS, Windows and Linux
- Updates through the built-in updater
Prices in USD; regional pricing is shown at checkout. Signup, billing and licenses are managed on portal.sizzy.co.
Questions
Straight answers, including about the alternatives.
No. Seeing every device at once is one part of it, and it is the part people notice first. Day to day Sizzy is the window you build in: a project switcher that restores your setup, isolated sessions for different users, a console and API client for all devices, screenshots and recording, and terminals and coding agents docked under the page.
Device mode emulates one viewport at a time inside a debugging panel. Sizzy shows several real device sizes side by side with scrolling, clicks, typing and navigation kept in sync, gives each device its own session, and adds a panel of tools DevTools does not have.
Read: where device mode falls shortIf side-by-side previews are all you need, Responsively may be enough. Sizzy goes further with isolated sessions, project workspaces, a unified console and API client, screenshots and Photo Studio, plus terminals and coding agents, and it is maintained as a paid product. The 14-day trial is the easiest way to feel the difference.
Read the comparisonBoth are paid browsers for developers and both are good. Polypane leans into accessibility audits and meta previews. Sizzy focuses on the full workflow around a project: devices, sessions, debugging, capture, terminals and agents in one window. Try both trials and keep the one that fits how you work.
Polypane vs Sizzy vs ResponsivelyThe agent panel is included in Sizzy. Sessions run through the Claude Code or Codex CLI installed on your machine, using your existing sign-in or API key. Model access and usage are billed by those providers under your plan. Sizzy adds project context, file mentions, plan mode, permission prompts and screenshots from your devices.
macOS (Apple silicon and Intel), Windows, and Linux. Updates arrive through the built-in updater, and the changelog for every release is public.
See the changelogCreate an account on portal.sizzy.co, download Sizzy for your platform and sign in. You get 14 days with every feature unlocked and no credit card on file, so nothing is charged automatically when the trial ends.
Yes. Alongside the monthly and annual plans there is a one-time lifetime license that includes future updates.
Start with the Sizzy Help Center for documentation. The changelog and feedback live on Sizzy's Glink page, and you can always email support directly.
Open the Help Center
Build the next thing in a browser that was built for it.
14-day free trial. No credit card. Every feature.
- 1Create your accountSign up on portal.sizzy.co. That is where your trial, license and billing live.
- 2Download for your platformGrab the macOS, Windows or Linux build from the portal.
- 3Sign in and buildOpen Sizzy, sign in, and every feature is unlocked for 14 days.
