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On-Device AI Translator Review: Offline LLM Translation for iPhone

·6 min readBy Hans Kuepper · Founder of PromptQuorum · Discovery engine for open-weight & open-source AI

On-Device AI Translator (version 1.2) translates on the iPhone with downloadable Hy-MT2, TranslateGemma and Qwen models, and offers Apple's built-in translation as a free engine. The AI models sit behind in-app purchases whose prices the sources do not show, and the privacy policy predates the app, so read the plans and privacy sections before relying on it.

Key Takeaways

  • Developer: a single developer listed on the App Store as Changwen Li, with no company behind it and no public app source code.
  • Maintenance: the last App Store update came five days before this check, so no stale-project warning applies.
  • Reach: the App Store shows 3.0 out of 5 from two ratings, so the app has little public track record.
  • Platforms: iPhone and iPad with iOS 18.4 or later; there is no Android or desktop build.
  • Languages: 20 translation languages, while the app's own interface is listed in English and Chinese.

📍 In One Sentence

On-Device AI Translator is a closed-source iPhone translation app that runs its models on the device and can stand in for the system translate sheet.

💬 In Plain Terms

You install it, download a translation model once, and from then on select text in any app to translate it without the text going to a server, according to the developer.

📌Note: This review is based on the App Store listing, the developer's support page and its privacy policy, checked on 24 October 2026. PromptQuorum has not installed, tested or benchmarked the app.

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On-Device AI Translator is an iPhone translation app from an individual developer listed on the App Store as Changwen Li (昌文 李). It translates with Apple's built-in translation or with language models that run on the phone, and it was first released on 1 March 2026. This review reflects its App Store listing, the developer's support page and its privacy policy as checked on 24 October 2026.

On-Device AI Translator Review: Offline LLM Translation for iPhone

What Is On-Device AI Translator?

On-Device AI Translator is an iPhone app that translates text with models running locally instead of calling a cloud translation service. According to its App Store listing it has two engines: System Translation, which uses Apple's built-in translation with language packs that the system downloads on first use, and on-device AI models (Tencent Hy-MT2 in 1.8B and 7B sizes, Google TranslateGemma 4B, Qwen3 and Qwen2.5) that the app downloads once and then runs offline. The privacy policy names llama.cpp as the inference engine.

The name varies by place. The US App Store title is "On-Device AI Translator", the description calls it "AI Translator", the developer's support page and privacy policy say "Local AI Translate", and the Austrian, German, Japanese, Korean and Brazilian storefronts all title it "本地 AI 翻译". The App Store ID (6759458075) is the same on every storefront checked.

Get It

The app is installed from the App Store; no Android build, desktop build or source code is offered. The developer has no product website beyond the support page below.

Platform
Where to get it
iPhone / iPadApp Store (iOS 18.4 or later, 109 MB)
WebsiteDeveloper support page (English and Chinese)
Privacy policyPrivacy policy (English, Chinese version linked there; effective 1 January 2025)
Bug reportsGitHub issues (website repository only, no app source)

Version reviewed: 1.2, released on the App Store on 19 October 2026 (first release 1 March 2026; 1.1 followed on 18 September 2026).

Features Confirmed by the Sources

Every item below comes from the App Store description and release notes.

  • Default translation app. After you set it as the default, selecting text in any app and tapping Translate opens the app, which translates with the chosen local model and can replace the original text in place or copy the result.
  • 20 translation languages. Simplified and Traditional Chinese, English, Japanese, Korean, French, German, Spanish, Italian, Portuguese, Russian, Arabic, Thai, Vietnamese, Indonesian, Turkish, Dutch, Polish, Ukrainian and Hindi; starred favorites stay at the top of every menu.
  • Voice conversations. Version 1.2 adds two-way voice conversations and continuous listening, plus a split view of originals and translations.
  • Managed model downloads. Version 1.1 added background downloads with resume and integrity checks; 1.2 improved offline downloads and language switching.

Free Tier and Paid Plans

The description names System Translation as the free engine and describes two in-app purchases that unlock the on-device AI models.

  • Free. System Translation with no model download; the system fetches a language pack the first time a language is used.
  • Lifetime. A one-time purchase that unlocks Hy-MT2 1.8B and the Qwen models, including inside the system translate sheet.
  • Pro. Everything in Lifetime plus the large models, TranslateGemma 4B and Hy-MT2 7B, billed monthly or yearly with a free 3-day trial.

Privacy and Network Use

The listing and the privacy policy both say that text never leaves the device when an AI model translates it. The App Store privacy label reads "Data Not Collected", which Apple notes is declared by the developer and not verified. The policy adds that the app has no account, makes no calls to external AI services, collects no analytics and has no separate crash-reporting SDK; crash reports go only to Apple, and only if you opt in.

What does use the network, per the policy: downloading GGUF model files at setup or when you pick a new model, and an optional check for app or model updates. The policy does not name where the models are downloaded from.

Two details need care. The policy is effective 1 January 2025, before the app's first release, and it calls the app "Local AI Translate". It also says translation text is held in memory only and never written to persistent storage, while version 1.2 saves transcripts and recordings on the device; the policy text does not describe those, nor the in-app purchases.

📌Note: The app is closed source, so none of these claims can be checked in code, and PromptQuorum has not audited network traffic. Anyone translating confidential material should verify the behavior on their own device.

Who Should Use It

  • People who translate private text on an iPhone. A local model keeps the text off a cloud service, per the developer.
  • Travelers and others without reliable data. Translation works offline once a model is downloaded.
  • Users who want to replace the system translate sheet. The app can be set as the default translation app.
  • Readers who want to compare models. Hy-MT2, TranslateGemma and Qwen are offered side by side.

What We Could Not Verify

  • Hands-on quality. PromptQuorum did not run the app, so translation quality, speed, battery use and the voice features are not assessed, and no model benchmark is claimed.
  • Prices and free scope. The listing text shows no price for Lifetime or Pro and does not say whether any AI model works without a purchase.
  • Source code and license. The app is closed source; the developer's GitHub organization hosts only its website repositories.
  • Data flows. With no code to inspect, the privacy statements above are the account of the developer and its policy.
  • Track record. Two App Store ratings and an individual developer, with no company or support commitment named in the sources.

Competitors and Alternatives

Locally AI

Platforms:
iOS, Mac
Price / license:
Free / closed source
Key difference:
General chat with open models on iPhone, iPad and Mac via MLX
Articles about Locally AI (5)

Also mentioned in:

TranslateBooksWithLLMs

Platforms:
Windows, macOS, Linux
Price / license:
Free / AGPL-3.0
Key difference:
Translates whole books and documents with a local Ollama model or cloud LLMs
Articles about TranslateBooksWithLLMs (2)

No other app in this list is a dedicated phone translator, so these are the nearest reviewed options rather than like-for-like rivals. Competitor details change often; confirm each app's current price, license and platforms on its own listing.

Compare in directory

Frequently Asked Questions

Can I run it on a Mac with Apple silicon?

The App Store lists Macs with Apple M1 or later but marks the app "Designed for iPhone. Not verified for macOS", so the developer has not verified the Mac experience, and PromptQuorum has not tried it.

What happens to saved transcripts and recordings?

Version 1.2 saves them on the device, per its release notes. The sources do not say how long they are kept or whether they can be deleted inside the app.

Which model should I choose?

The description says to pick one to match the device's memory and the quality needed. It gives no memory figures, download sizes or quality comparisons for the models.

Verdict

On-Device AI Translator is an iPhone translation app that runs Hy-MT2, TranslateGemma or Qwen models on the device, covers 20 languages and can replace the system translate sheet, with Apple's built-in translation as a free fallback. It is also actively updated, with a release five days before this review was checked. Against that, it is closed source, new, rated by only two people, tied to purchases whose prices the sources do not show, and described by a privacy policy older than the app. It suits readers who want a local translation model on an iPhone and accept a young, closed app; readers who want auditable code can compare Private Mind or PocketPal AI.

Sources

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