The Ghostwriter in the Curriculum: LingFit's AI Packs Put to the Test

Every great writer has at some point feared a ghostwriter, and every busy politician has employed one. The ghostwriter is the most ambivalent figure in the literary world: invisible, useful, a little suspect. LingFit has written such a ghostwriter into its curriculum. You give it a topic, and it delivers a lesson. The question is whether you should trust it.

How the commission works

In the app the feature is called ‘custom packs’ (on the website, ‘Extra Packs’), and according to the maker it is what most clearly sets LingFit apart from other apps. There are two routes.

By topic: You type in any topic and choose a word type: Basic Words, Advanced Vocabulary, Ultra Advanced or Specialist Words. LingFit then suggests a vocabulary list, which you can review and edit before the chapter is created.

By word list: You bring 1 to 20 words of your own. Either you type them in, choose them from your saved words, or photograph them: a vocabulary list from school, a worksheet, a book page, a menu, a sign. The app reads the text and extracts the vocabulary.

In both cases the result is a complete chapter in the ‘Yours’ tab, with its own emoji, the same exercise formats, audio files and images as the main course. You can rename it, change the description, and make it public after an automatic safety check. Public packs from other learners can be searched, saved and liked.

Two idiosyncratic commissions

To test the idea, we mentally set it two very British topics that no textbook would ever cover.

The first: the rules of cricket in German. A topic that hardly anyone can explain fully even in English. Here the point of the word-type choice becomes clear. Basic Words would probably stick to ball, bat and pitch; Specialist Words would have to venture into terms for which German sometimes has no established equivalents at all. This is precisely where the intermediate step matters: because LingFit shows the suggested list before building, the learner can strike out coinages before they become exercises.

The second: a canal-boat holiday in the Netherlands. Here the task is more rewarding. Locks, bridges, mooring, provisions, the friendly small talk with the bridge keeper: everyday, concrete words that a guidebook only skims. Dutch is part of the offer for English speakers, and such a pack combines specialist vocabulary with exactly the kind of conversational scraps you need on the ground.

An honest note: how good the word choice turns out in any individual case depends on the generated result, and we cannot guarantee it for every conceivable topic. What we can judge is the construction, and that is remarkably well thought out.

The ghostwriter is only as good as its editor, and here the editor is the learner.

Why the design convinces

Three decisions make the packs more than a gimmick.

First: the list comes before the chapter. Many AI tools present a finished result and leave it to the user to find the mistakes. LingFit inserts an editorial step in between. That is the principle of editing, and with generated content it is the only sensible one.

Second: the chapter is fully fledged. A pack does not generate a list of flashcards but the same twelve exercise formats as the course: swiping, picture-to-word, listening exercises, sentence building, fill-in-the-blank, dialogue building, speaking. A word you have chosen yourself is thus put through the same mill as a word from the curriculum.

Third: errors are provided for. If creation fails, the credit is automatically refunded. And in every lesson a problem can be reported, such as a poor translation or a strange image. An AI-powered app that builds in these exits has understood that generation includes error.

The credit model

The ghostwriter does not work for nothing. Each pack costs one credit. Every new account gets one credit free, and more are available in bundles (Starter, Most Popular, Best Value), which according to the maker do not expire. In the US App Store on 10 October 2026, five credits cost $5.99, twelve credits $9.99 and twenty credits $14.99; in the German store, €6.99, €9.99 and €17.99. On top of that comes the subscription, which covers the rest of the content.

You can read this model from two directions. Positively: if you only occasionally need a pack, you pay only for that. Critically: the app’s best idea is also its additional checkout. We consider that defensible, because every generation incurs real computing costs, but we would like interested parties to know this before signing up. A monthly credit allowance in the subscription is not confirmed.

Limits of the commission

A ghostwriter writes what you tell it to, and no more. The packs deliver vocabulary and exercises; they do not deliver conversation partners, human correction, or a guarantee that every specialist translation is correct. Anyone building a pack for a professional purpose, such as care vocabulary, should understand it as preparation, not as a substitute for professional training. And the packs operate in the same 42 language directions as the course; for Japanese or Arabic, even the best commission will not help.

The public reading room

One aside still deserves mention: the ability to make packs public. After an automatic safety check, other learners can find, save and like them. This turns the private ghostwriter into a small lending library: whoever has built a pack on canal boats need not be the last to use it. How large and well organised this reading room is, we cannot judge.

Our verdict

The custom packs are the reason we take LingFit more seriously than its cheerful façade suggests. They solve an old problem of language teaching — the problem of vocabulary chosen by others — with a clean, easily edited process. 4.6 stars for a ghostwriter that is diligent, honest about its mistakes, and takes its client pleasingly seriously. We withhold the full five only because every manuscript must be paid for separately, and because in the end the learner still has to proofread.