Sizzy
Sizzy is a bootstrapped, Chromium-based development browser that lets web developers, designers, and freelancers test responsive web layouts across multiple device viewports simultaneously with synchronized interactions. Founded by Kitze in 2018.
- Company typePrivate
- Founded2018
- HeadquartersDelaware, United States
- Headcount1–10
- GTM typeB2C
- OfferingSoftware
What Sizzy does
Sizzy is a privately held, bootstrapped software product operated by founder Kitze, functioning as a specialized Chromium-based development browser for testing responsive web designs. Built on Electron with Chromium under the hood, it allows Chrome extension compatibility and renders multiple device viewports (iPhone, iPad, Android, desktop) side-by-side in a single window with synchronized scrolling, clicking, and form inputs. The product includes 100+ developer-specific features such as Universal DevTools, isolated multi-session testing for different user roles, project-scoped workspaces, Photo Studio for device-framed mockups, QR code sharing for mobile testing, and theme/i18n switching. Since its 2018 launch, the product has shipped 738 releases and 11,519 GitHub commits and is used by 10,000+ developers, including individual advocates at NVIDIA and recognized figures in the frontend ecosystem (Brian Lovin, Kent C. Dodds, Stefan Natter).
The company monetizes through three pricing tiers sold directly via a self-serve portal at portal.sizzy.co with a 14-day free trial: a $15/month subscription, a $12/month annual plan ($144/year), and a $499 lifetime license with transferable rights and priority support. All payments are Stripe-processed. Go-to-market is product-led growth with content marketing as the primary acquisition channel — over 100 educational blog posts, public free tools (Viewport Checker, CSS Breakpoint Checker, Responsive QA Checklist), and an active Twitter/X presence under the founder's handle. Sizzy's primary customers are web developers (frontend and full-stack), with secondary segments in UX/UI designers and freelancer/agency users who need to deliver responsive client work. The company holds Product Hunt #1 Product of the Day, #1 Product of the Week, and #3 Product of the Month recognitions.
Sizzy firmographics
Firmographics- Name
- Sizzy
- Legal name
- Sizzy (operated by Kitze)
- Website
- https://sizzy.co
- Company type
- Private
- Founded year
- 2018
- Operating status
- Operating
- Headcount range
- 1–10 employees
- Short description
- Sizzy is a bootstrapped, Chromium-based development browser that lets web developers, designers, and freelancers test responsive web layouts across multiple device viewports simultaneously with synchronized interactions. Founded by Kitze in 2018.
- Ownership category
- akta.pro rank
Where Sizzy is headquartered
LocationHeadquarters
- HQ city
- Delaware
- HQ country
- United States
- HQ region
- North America
Markets served
Sizzy business model
Business model- GTM type
- B2C
- Offering type
- Software
- Cost components
- Technology or R&D, Personnel, Marketing or Sales, Infrastructure, Operations
Revenue model
- Subscription - Monthly: Flexible monthly billing at $15/month for short-term projects. All features unlocked with standard email support.
- Subscription - Annual: Annual subscription at $12/month (billed $144 yearly). Best value plan with priority email support and locked-in pricing on renewal.
- Lifetime License: One-time payment of $499 for lifetime access. Includes all future updates, transferable license, priority email support, and direct line. Immune to future price changes.
Pricing tiers
| Model | Billing | Price |
|---|---|---|
| Subscription | Monthly | Monthly subscription - flexible billing for short-term work |
| Subscription | Annual | Annual subscription - best value for working developers |
| One time/ perpetual license | Multi-year contract | Lifetime license - pay once, own it indefinitely |
Go-to-market motion1 record
Distribution channels1 record
Marketing channels5 records
Sizzy product offering
Product offeringCore offering
Sizzy is a specialized browser built on Chromium and Electron that displays multiple device viewports side-by-side with synchronized scrolling, clicking, and form inputs for testing responsive web designs. It enables developers to debug CSS visually via a universal DevTools panel, test multiple user accounts simultaneously through isolated sessions, save per-project configurations, and capture device-framed screenshots and videos. The product is sold as a subscription or lifetime license with a 14-day free trial, no credit card required.
Product overview
Sizzy is a single focused product — a development browser built on Chromium that serves as an alternative to Chrome DevTools device mode for responsive UI testing. The product centers on synchronized multi-device viewport previews, universal DevTools, session management for multi-account testing, Photo Studio for device-framed screenshots, and a suite of public web tools (Viewport Checker, Responsive Screenshot Generator, Responsive QA Checklist, Website Breakpoint Finder, Screenshot Comparison Checklist, Browser Size Cheat Sheet, CSS Breakpoint Checker). All of these are integrated capabilities within the same Sizzy application rather than separate standalone modules.
Differentiator
Problem solved
Functional benefit
Products and services
- Sizzy Sizzy is a Chromium/Electron-based developer browser that displays multiple device viewports side-by-side with synchronized scrolling, clicking, and form inputs. It is designed for individual web developers, frontend/full-stack engineers, UX/UI designers, freelancers, and small agencies that need to test and debug responsive UI across iPhone, iPad, Android, and desktop dimensions, simulate multiple user accounts via isolated sessions, use a universal DevTools panel, manage per-project workspaces, and capture device-framed screenshots and recordings. Sold as a monthly subscription ($15/month), annual subscription ($12/month billed yearly), or lifetime license ($499 one-time), with a 14-day free trial and no credit card required.
Quantifiable outcome
- Test every breakpoint at once, reducing responsive QA time significantly
- +2 more outcomes
Companies that use Sizzy
Customer profileNamed customers5 records
Segments3 records
Ideal customer profiles2 records
Sizzy technology and API
TechnologyTechnology focussed Yes
API detail
- Has API
- No
- API docs
- API detail
Core technology
AI maturity
App detail
Feature12 records
Sizzy partnerships and signals
Strategic signalScale indicators5 records
Recent moves5 records
Expansion highlights5 records
Sizzy competitors and assessment
Company assessmentBroad incumbents
- BrowserStack: Large-scale cross-browser and real-device cloud testing platform used by enterprises. Overlaps with Sizzy's responsive-testing use case but serves a much broader cross-browser and QA audience.
- Sauce Labs: Enterprise cross-browser and automated testing cloud. Adjacent to Sizzy's responsive testing focus but oriented to QA automation at scale rather than developer-led responsive QA.
- LambdaTest: Cloud-based cross-browser and cross-device testing platform with enterprise features. Offers LT Browser as a free multi-viewport tool that competes directly with Sizzy's core workflow.
- Chrome DevTools: Built-in browser developer tools from Google. Provides device emulation and responsive inspection natively in Chrome, the baseline alternative Sizzy is built to improve upon.
Others
- Applitools: Visual AI testing and visual regression platform for web and mobile UIs. Adjacent to Sizzy's responsive-testing use case, focused on automated visual QA rather than synchronous manual testing.
- Percy: Visual review and visual regression testing tool from BrowserStack. Adjacent category to Sizzy, serving frontend teams that need screenshot-based visual diffing across breakpoints.
Direct peers
- Blisk: Multi-device browser aimed at developers for simultaneous responsive testing across phones, tablets, and desktops. Direct overlap with Sizzy's synchronized multi-device testing proposition.
- Responsively: Free, open-source browser for testing responsive designs across multiple device viewports. Targets the same workflow as Sizzy and is named directly in Sizzy's competitive comparison content.
- Polypane: Paid developer browser for responsive and multi-viewport testing with synchronized interactions. Polypane is the closest commercial alternative to Sizzy and is explicitly named as a competitor in Sizzy's own comparison content.
- LT Browser: LambdaTest's free multi-viewport responsive testing browser. Provides side-by-side device previews targeting the same developer use case as Sizzy, but free and backed by a larger testing platform.
Market position
Strengths4 records
Weaknesses5 records
Competitive moat4 records
Key risks6 records
Key highlights6 records
Customer concentration
Sizzy social profiles
Digital presenceSizzy financial estimates
Financial estimateRevenue estimate
Valuation estimate
Sizzy leadership team
Management profileNumber of profiles
Profiles1 record
Sizzy funding detail
Funding detailFunding overview
Funding rounds
Investors
Funding detail is available on the Subscription and Enterprise plan.Contact sales →
Sizzy M&A and investment
M&A and investmentM&A
Investments
M&A and investment is available on the Subscription and Enterprise plan.Contact sales →
Frequently asked questions about Sizzy
What does Sizzy do?
Sizzy is a specialized browser built on Chromium and Electron that displays multiple device viewports side-by-side with synchronized scrolling, clicking, and form inputs for testing responsive web designs. It enables developers to debug CSS visually via a universal DevTools panel, test multiple user accounts simultaneously through isolated sessions, save per-project configurations, and capture device-framed screenshots and videos. The product is sold as a subscription or lifetime license with a 14-day free trial, no credit card required.
Is Sizzy a public or private company?
Sizzy is a private company. It is classified as founder individual operated bootstrapped and is currently operating.
When was Sizzy founded?
Sizzy was founded in 2018. It employs 1 to 10 people.
Where is Sizzy based?
Sizzy is headquartered in Delaware, United States, in the North America region.
How does Sizzy make money?
Three revenue lines are on record. Subscription - Monthly is the primary driver. The others are subscription - Annual and lifetime License.
Who are Sizzy's main competitors?
Broad incumbents on record are BrowserStack, Sauce Labs, LambdaTest and Chrome DevTools. Others are Applitools and Percy. Direct peers are Blisk, Responsively, Polypane and LT Browser.
Does Sizzy have an API?
No public API is recorded for Sizzy.