LEGAL

Licences & Attributions

Last updated July 2026

Why this page exists

Zella is built on other people’s work as well as ours. Some of those licences require attribution, and all of them deserve it. This page lists everything third-party that ships inside the app, and what governs it.

Copies of the full licence texts are included in the app bundle alongside the components they cover.

Speech recognition

WhisperKit (iPhone & iPad) - © 2024 Argmax, Inc. - MIT Licence - project

WhisperKit runs OpenAI’s Whisper model on Apple silicon through Core ML. Zella uses it on iPhone and iPad for verbatim transcription, which is what lets filler-word removal find an “um” at all. The model itself (openai_whisper-base, roughly 145 MB) is downloaded once from Hugging Face on first use rather than bundled, under its own upstream licence.

SwiftWhisper by exPHAT - MIT Licence whisper.cpp by Georgi Gerganov - MIT Licence Whisper model weights by OpenAI - MIT Licence

Used by the Mac app for the same purpose.

Voice noise removal

DeepFilterNet3 - Apache Licence 2.0

  • Core ML conversion: aufklarer/DeepFilterNet3-CoreML (Hugging Face), Apache 2.0
  • Original model and research: Rikorose/DeepFilterNet, dual-licensed MIT / Apache 2.0
  • Swift DSP reference: soniqo/speech-swift, Apache 2.0

Licensed under the Apache Licence, Version 2.0; a copy is available at apache.org/licenses/LICENSE-2.0. Distributed on an “AS IS” basis, without warranties or conditions of any kind, express or implied.

RNNoise - BSD 3-Clause Licence © 2017 Mozilla; © 2007-2017 Jean-Marc Valin; © 2005-2017 Xiph.Org Foundation; © 2003-2004 Mark Borgerding. Redistribution and use in source and binary forms, with or without modification, are permitted provided the conditions of that licence are met. This software is provided by the copyright holders and contributors “AS IS”, and any express or implied warranties are disclaimed.

A component that is deliberately not in the App Store build

Robust Video Matting by Shanchuan Lin et al. is licensed under the GNU General Public Licence v3.0, whose terms are incompatible with App Store distribution. App Store builds of Zella do not include it and use Apple’s Vision framework for person matting instead. It may appear only in direct-download builds of the Mac app. The GPL-3.0 text is at gnu.org/licenses/gpl-3.0.html.

Fonts

All bundled caption and title fonts are used under the SIL Open Font Licence 1.1. The full licence text ships with the app.

  • Montserrat - © The Montserrat Project Authors - project
  • Poppins - © The Poppins Project Authors - project
  • Anton - © The Anton Project Authors - project
  • Bebas Neue - © The Bebas Neue Project Authors - project

Sound effects and music: original, not licensed

Zella’s 30 sound effects and its music beds are not stock audio. They are synthesised on your device by Zella’s own procedural audio engine the first time each one is used, then cached locally. They are original works, they add nothing to the app’s download size, and they are royalty-free for anything you make with them - commercial work included. There is no third-party rights holder to credit, and nothing to clear before you publish.

Apple frameworks

Zella is built on Apple’s own on-device frameworks, used under the Apple Developer Program Licence Agreement: ScreenCaptureKit and ReplayKit for capture, AVFoundation and Core Media for editing and export, Vision for subject segmentation and face-aware reframing, the Speech framework for transcription fallback, the Translation framework for on-device caption translation, Core ML and the Neural Engine for model inference, and StoreKit for purchases.

Optional third-party services

These are not bundled and are not used unless you switch them on. When you do, their terms govern what you download, not ours.

  • Pexels - licence - optional stock b-roll, with your own free key.
  • Pixabay - licence - optional stock b-roll, with your own free key.
  • AI providers - OpenAI, Google, Groq, OpenRouter, or a local model via Ollama - used by the AI Assistant with a key you supply, under that provider’s own terms.

Zella’s default Auto B-Roll needs none of these: it generates cutaway cards on your device, with no key and no network.

Background images

The ten backdrop images bundled for background replacement were made for Zella, not licensed from a stock library. There is no third-party rights holder, nothing to clear, and no attribution requirement for you: use them in anything you make, commercial work included.

Your exports

To be explicit, because creative tools are often vague about it: you own what you make. Nothing in Zella’s licensing places any claim, watermark, royalty or attribution requirement on your finished video, on any tier including the free one. The synthesised sound effects and music you use inside it are yours to publish and monetise.

Corrections

If you believe something here is incomplete or wrongly attributed, tell us at legal@zellahq.com and we will correct it.