- Firefox: ProtonMail (unofficial) on Firefox Addons
- Microsoft Edge: ProtonMail (unofficial) on Microsoft Edge Addons
- Chromium based browsers: ProtonMail (unofficial) on Chrome Web Store
- Opera: ProtonMail (unofficial) on Opera addons
run npm i && npm run build:firefox or npm i && npm run build:chromium. Extension will compile to ./build, run npm run deploy to create the packed extensions zip.