Fontify

Your web, your type.

A Chrome & Firefox extension by XDan. Make the web feel like you, with Material 3 Expressive controls, your favourite typefaces, and a little attention to the details.

What you can do

• Pick from 1,950 Google Fonts families in a bundled searchable catalogue. Filter by category, save favourites, and preview fonts on hover or keyboard focus. No API key needed.
• Upload TTF/OTF fonts, including variable fonts. Files stay on your device. Static faces keep their original weight and italic descriptors; variable faces retain their weight range.
• Choose separate serif, sans-serif, regular, bold and italic families and weights. Serif/sans-serif settings follow the default when left unset. Explicit bold/italic families override category choices; otherwise their style follows the source text category. Bold italics use the italic profile. If a family has no italic face, the browser can synthesise it.
• Leave monospace text, code and icon fonts alone by default, or enable Code & monospace replacement with its own typeface and weight (JetBrains Mono is preselected). Detection uses known font families and fixed-pitch measurements.
• Highlight text, right-click Fontify, and override either its original font family or that text/code block. Choose a replacement font, weight, and scope. Rules persist across reloads; a block rule is scoped to its host.
• Add exceptions for a website, font family, or CSS selector. Exceptions win over overrides, including within restyled parent elements.
• Pause Fontify globally or on the current site, without reloading. The original inline values and priorities are restored.
• Switch between light, dark and system themes. The corner toggle switches light/dark. Reduced-motion preferences are respected.
• Export/import settings, exceptions, rules and custom fonts in a single backup. Pause remote downloads or clear the Google font cache.

Install a development build

Download the latest fontify-packages artifact from Actions, or build locally. Tag builds also attach packages to Releases.

Chrome / Chromium

1. Extract fontify-1.1.0-chrome.zip.
2. Open chrome://extensions and enable Developer mode.
3. Choose Load unpacked and select the folder containing manifest.json.
4. Refresh any already-open websites once after installation. Later settings changes apply live.

A CRX3 package is also built. A self-signed CRX is useful for compatible development/managed distribution, but is not a Chrome Web Store signature and cannot be installed on every standard Chrome platform by double-clicking. Load unpacked is the reliable development route. Chrome 120 or newer is required.

Firefox

1. Extract fontify-1.1.0-firefox.zip.
2. Open about:debugging#/runtime/this-firefox.
3. Choose Load Temporary Add-on and select manifest.json.
4. Refresh already-open websites once after installation.

Temporary add-ons are removed when Firefox restarts. The unsigned XPI is a development package; normal persistent Firefox installation requires Mozilla signing. The workflow can produce an unlisted signed XPI when AMO credentials are configured. Firefox 140 or newer is required.

Build & test

Use Node.js 22 or newer:

npm ci
npm test
npm run build
npm run lint:firefox
npx playwright install --with-deps chromium
npm run test:browser
npm run package

Output:

File / directory	Purpose
dist/chrome/	Unpacked Chromium MV3 build; service worker background
dist/firefox/	Firefox MV3 build; event-page background
artifacts/fontify-1.1.0-chrome.zip	Chrome development/store upload package
artifacts/fontify-1.1.0-firefox.zip	Firefox source package
artifacts/fontify-1.1.0.crx	Self-signed CRX3
artifacts/fontify-1.1.0-unsigned.xpi	Unsigned Firefox development package

npm run catalogue:update refreshes the Google Fonts metadata snapshot. Catalogue access is never needed during an ordinary build. Fonts themselves download on demand through the background extension context and are cached in IndexedDB. All executable code and UI assets are bundled locally.

Browser tests run the actual Chrome extension against a local fixture, with deterministic Google font responses. They cover page security restrictions, dynamic text, open shadow roots, code/icon protection, family selection, uploads, exceptions, persisted code-block overrides, restoration and light/dark UI. Unit tests cover settings, rule precedence, family safety and uploaded font metadata. Firefox is manifest/lint validated; the automated interactive integration suite uses Chromium.

Mozilla's linter currently reports one UNSAFE_VAR_ASSIGNMENT warning in the bundled Lit dependency's template parser. Application strings are passed through Lit's escaped bindings; Fontify does not use unsafeHTML or remote executable code. Review this known dependency warning during store submission rather than suppressing it.

Automated builds and signing

Every push to main and every pull request builds, tests, validates, packages, and uploads artifacts. Tags matching v* also create GitHub Releases.

Optional repository Actions secrets:

Secret	Purpose
CHROME_PRIVATE_KEY	PEM RSA private key for a stable CRX extension identity. Without it, CI generates a development key per build.
AMO_JWT_ISSUER	Mozilla Add-ons API key for signing tag builds
AMO_JWT_SECRET	Matching Mozilla Add-ons API secret

The Chrome private key is never included in published artifacts. A first local package build creates artifacts/development-key.pem; preserve it privately if you want the same local CRX identity. For local signing with another key, set CHROME_KEY_PATH to its path.

See release instructions for the exact steps. Store submission and credential creation are not automated.

Behaviour and boundaries

• Profiles apply to normal webpage text, form controls, dynamically inserted text, iframes where permitted, and open shadow roots. Enable Code & monospace to restyle fixed-width text everywhere, or use an explicit saved override for individual fonts/blocks. Icons remain protected.
• Serif/sans-serif classification uses the original CSS font stack, Google Fonts metadata, and known system serif families. Unknown custom fonts use their CSS generic fallback, or the sans-serif/default profile when no category can be inferred. Code elements and measured fixed-pitch fonts use the optional monospace profile.
• Site patterns use exact hostnames; *.example.com includes the parent and its subdomains. Path-specific exceptions are not supported. A most-recent matching override wins; exceptions take priority.
• Block selectors may stop matching if a website redesigns its DOM. Recreate that rule when needed. Persistent block overrides cannot target inside a shadow root; use a font-family rule there.
• A font is applied only once its data loads. Failed downloads leave the original page typography in place. If downloads are disabled, uncached Google fonts cannot load; cached/custom fonts remain usable.
• Static uploaded fonts cannot acquire true weights they do not contain. The browser uses the closest face and may synthesise bold or italic. Use variable fonts or separate uploaded faces for precise results.
• Browser settings pages, extension stores, built-in PDF viewers, canvas-rendered text and closed shadow roots are outside the extension's reach. Fonts inside inaccessible frames cannot be changed.
• Restyling may change line wrapping and layout. No extension can guarantee identical page layout with a different typeface.

Privacy & permissions

No analytics, accounts, history collection, or external settings sync. Custom files and backups stay local unless you choose to share an exported backup. Selected text is stored locally only while composing an override, and its short label is retained in a saved rule. See Privacy.

storage saves settings; contextMenus adds right-click actions; activeTab identifies the page used by the popup. Access to websites lets the content script replace typography and permits the background to download Google font assets. The extension does not use an external server.

Licence & credits

MIT, copyright 2026 XDan. Built with matraic/m3e, with the visual direction of XDan's site: Outfit, rounded tonal surfaces, expressive shapes, and restrained motion.

The UI's bundled Outfit font is SIL OFL licensed. See third-party notices and the packaged licenses/ directory. Uploaded fonts remain subject to their own licences.