We built 4 Chrome extensions for our SaaS clients. Here is the exact stack, costs, and common pitfalls.
By David Friedman, Founder of AppBrewers
A Chrome extension is the cheapest distribution channel for a SaaS. It puts your product inside the user’s browser, one click away from daily use. We built 4 Chrome extensions for SaaS clients in 2025. Here is what we learned.
Why Build a Chrome Extension?
| Benefit | Impact |
|---|---|
| Distribution | 3.5 billion Chrome users, zero ad spend. |
| Retention | Users see your icon every day. |
| Onboarding | Extract data from the current page automatically. |
| Virality | Share features via screenshots and links. |
| SEO | Chrome Web Store pages rank in Google. |
What You Can Build
| Extension Type | Complexity | Example | Timeline |
|---|---|---|---|
| Content script | Low | Highlight text, inject buttons | 1-2 weeks |
| Sidebar / panel | Medium | AI assistant on every page | 2-4 weeks |
| Full-page override | Medium | Replace new tab page | 2-3 weeks |
| Background + API | High | Sync data, webhooks, auth | 3-6 weeks |
| Manifest V3 service worker | Medium | Event-driven background tasks | 2-4 weeks |
Tech Stack
| Layer | Technology | Why |
|---|---|---|
| Framework | Plasmo | Modern React-based framework for extensions. |
| UI | React + Tailwind | Reuse your web app components. |
| State | Zustand | Lightweight, works in isolated contexts. |
| Storage | Chrome Storage API | Syncs across devices. |
| Auth | Firebase Auth | Same auth as your web app. |
| API | REST / GraphQL | Reuse your existing backend. |
| Packaging | Plasmo CLI | One command to build and zip. |
Cost by Extension Type
| Type | Cost Range | Includes |
|---|---|---|
| Simple content script | 1,500-3,000 Euro | UI injection, basic API calls |
| Sidebar assistant | 3,000-6,000 Euro | React UI, auth, settings |
| Background-heavy | 5,000-10,000 Euro | Sync, webhooks, advanced APIs |
| Full new-tab replacement | 4,000-8,000 Euro | Custom dashboard, widgets |
Common Pitfalls
Ignoring Manifest V3
Manifest V2 is deprecated. Chrome rejects V2 extensions. Use V3 from day one.
No Onboarding Flow
Users install, see a blank icon, and forget about it. Show a welcome page on first install.
Storing Secrets in the Extension
Chrome extensions are client-side code. API keys can be extracted. Use a backend proxy.
Not Updating Regularly
Chrome Web Store reviews take 1-3 days. Plan releases ahead. Automated CI/CD helps.
Chrome Web Store SEO
| Element | Best Practice |
|---|---|
| Title | Include your main keyword + benefit |
| Description | First 2 sentences matter most. Use keywords. |
| Screenshots | 5 screenshots, 1280x800, showing real use cases |
| Promo video | 30-60 seconds, no sound needed |
| Reviews | Ask users after 7 days of use |
| Category | Pick the most specific one |
Need an Extension Built?
We have built 4 Chrome extensions for SaaS companies. Fixed pricing. 2-6 weeks.
Originally published on the AppBrewers Blog.
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