Make sure the extension is turned on (see Getting started above). On iPhone and iPad, Tessel lives in the page menu next to the address bar rather than on the toolbar. On Mac, if the button is missing from the toolbar, choose View › Customize Toolbar and drag it in.

Safari doesn't let extensions run on some pages, such as the Start Page, settings pages and certain Apple websites. On other pages, check that Tessel is allowed on all websites, then reload the page.

Automatic translation needs permission on all websites. It's off by default; turn it on in the app under Translation › Auto-Translate, and choose which page languages it applies to. You can also set a single website to always translate from the popup. Automatic translation uses Apple Translation, so you're never charged by an AI provider without tapping Translate.

Apple Translation runs on your device and needs the languages downloaded first. Open the app and go to Apple Translation Languages to download the packs you need. If Apple Translation doesn't support a language pair, translate that page with an AI model instead.

In the app, open AI Models under Translation Services, add a provider (such as an OpenAI-compatible service or Anthropic), enter your API key and verify it, then pick a default model. In the popup, choose the model next to Apple Translation and tap Translate. Your key is stored in iCloud Keychain and page text is sent directly to that provider.

Apple Translation is free. When you use an AI model, your provider bills you directly for the requests. To keep costs down, Tessel translates the part of the page around where you're reading, caches every translated paragraph so it's never billed twice, and never uses an AI model for automatic translation across all websites.

The popup shows the reason — for example an invalid API key, no remaining quota, a network problem, or the model refusing to answer. Fix the issue in the app or with your provider and tap Retry, or switch to Apple Translation for that page.

If a paragraph can't be translated, Tessel leaves the original text rather than showing something broken. When an AI model misses a paragraph and the Apple Translation language pack is installed, Tessel fills it in with Apple Translation. If you see this often on a site, please send feedback from the popup.

Tap the source language in the popup and choose the right one. Tessel remembers your choice for that website.

Open the popup and tap Show Original. Tap Translate again and the translation comes back instantly from the cache.

Settings, website rules and AI providers sync through iCloud, and API keys through iCloud Keychain. Make sure all devices are signed in to the same Apple Account with iCloud and iCloud Keychain turned on. Syncing can take a few minutes.

Open the app and choose Clear Translations under Translation Cache. Apple Translation language packs are managed by the system: on iPhone and iPad in Settings › Apps › Translate, on Mac in System Settings › General › Language & Region.