Isabella

Isabella is a female British English AI voice rated C on the OfflineTTS quality scale. Speech synthesis runs in your browser with no signup or per-character fees.

Best for: General voice-over

Quality rating explained: C is a catalog discovery label, not a measured MOS score, a public leaderboard position, or a guarantee for your script. Audition names, numbers, pacing, and chunk joins before publishing.

The Isabella voice uses Kokoro's browser phonemizer and local WebGPU or WebAssembly synthesis. After the initial model download, English generation works completely offline.

Preview transcript: the sample player above reads: “I put the kettle on before opening my laptop this morning. While the tea was brewing, I stood by the window and watched the clouds move over the rooftops. It was a gentle way to begin a day that looked busy on paper.” Listen to that clip before generating your own text; it is the shortest way to judge pronunciation, pace, and whether the British English phonemization path fits your script.

Reviewing British English text with this preset: British English differs from the American presets in vowel quality and in non-rhotic word endings. Check place names, "schedule", "route", and any word where your audience expects one accent over the other before you export narration for a British audience.

Grade context: A C grade describes a preset that needs real review. Listen for metallic edges, breath noise, or uneven energy before using it in published audio.

What the browser downloads: English Kokoro ships two model files here: a 305 MB 4-bit build and a 326 MB full-precision build. The browser downloads one of them on first use and keeps it in cache; the phonemizer for English also runs locally.

Asset identity: this preset maps to the cached asset fingerprint cdd4c370, so it can be told apart from a same-named voice on another engine even when the label in the picker looks identical.

Other British English voices: Emma (female, grade B-), Alice (female, grade D), Lily (female, grade D). Switching between them on the same sentence is the fastest way to hear whether one suits the script better.

Explore other British English voices or browse the complete voice library for your project.