Announcing Extension.js 3.0.0#

February 18, 2026

Extension.js 3.0.0 is now available.

This release is focused on one thing: helping teams ship production browser extensions with less setup, clearer workflows, and better defaults across Chrome, Edge, and Firefox.

What ships in v3#

Version 3.0.0

• Stronger cross-browser workflows across Chrome, Edge, and Firefox with one command surface.
• Expanded template experience for modern stacks including TypeScript, React, Vue, Svelte, and Preact.
• Improved development update behavior with clearer HMR, hard-reload, and restart-required boundaries.
• Better production confidence workflows across troubleshooting, security checks, performance checks, CI templates, and Playwright E2E.
• More predictable project configuration through extension.config.js and browser-aware build output.
• A cleaner documentation and homepage experience designed for faster onboarding and lower cognitive load.

The day-one flow is simpler#

Use one path from project creation to production output:

1. create to scaffold.
2. dev to iterate quickly.
3. build to generate production artifacts.
4. start or preview to validate production behavior.

npx extension@latest create my-extension --template=new-typescript
cd my-extension
pnpm dev
pnpm build

Better for teams, not just demos#

v3 is designed for real teams maintaining real extension codebases:

• Typed templates and framework-first baselines reduce setup drift.
• Browser-targeted builds and flags make compatibility checks explicit.
• Workflow docs now map directly to release confidence tasks.
• Security and performance guidance is integrated into standard delivery flow.

Who this release is for#

• Teams migrating from custom extension build scripts.
• Web developers moving from app development to extension development.
• Teams standardizing extension DX across multiple repos and contributors.

Upgrade notes#

If you are already using Extension.js:

• update the package to latest,
• prefer canonical template slugs (new-react, new-typescript, new-vue, etc.),
• keep your command flow aligned with create -> dev -> build.

Thanks#

Thanks to everyone building with Extension.js, reporting issues, and improving docs and templates with feedback.

v3 is a major step forward, and we are just getting started.

Cezar Augusto
Creator and Lead Developer, Extension.js