PromGee vs Duolingo: Which Fits Your English Grammar Practice?

Duolingo and PromGee are both used by English learners, but they are built around different ideas. Duolingo teaches a whole language through short, game-like lessons across speaking, reading, listening and writing. PromGee assumes you already study English and want to work on specific grammar areas, such as articles, tenses or prepositions, and understand why each answer is correct. The comparison below uses Duolingo's App Store listing and official blog as sources.

PromGee and Duolingo at a glance

Which is better for learning grammar rules?

For targeted grammar work, PromGee is the more focused tool. You choose one of 14 learning categories (Prepositions, Grammar, Vowels, Tenses, Articles, Punctuation, Spellings, Collocations, Verb Forms, Phrasal Verbs, Core Skill Building, Idioms, Vocabulary, Pronunciation), answer questions, and read an AI explanation of why each answer is right or wrong. Explanations are available in 40+ languages, so you can read the rule in your first language while practicing English.

Duolingo's strength is breadth. Its App Store description says its game-like lessons build speaking, reading, listening and writing skills, which makes it a good way to keep regular contact with a language. If your problem is one specific pattern, such as since vs for or when to use the, a category you can repeat on demand is usually more direct.

Is Duolingo free, and is PromGee free?

Duolingo's App Store listing shows the app as free with in-app purchases and states that every course is free. Super Duolingo is an optional subscription, paid monthly or annually, that removes ads and adds perks such as Unlimited Energy and Monthly Streak Repair. The US App Store listed several Super Duolingo in-app purchase prices, from $9.99 to $119.99, when we checked; the price you see depends on plan and region.

PromGee's desktop app is a one-time $25 USD purchase with a lifetime license and no PromGee subscription. The license does not include an unlimited AI quota; provider limits apply, and bring-your-own-key usage follows the provider's pricing. The free web tools, including a prepositions quiz and a vocabulary quiz, cost nothing; their AI explanations are in English. See the pricing page for the license details.

Can PromGee replace Duolingo?

Not for most people. PromGee teaches only English, runs only on Windows, and needs an internet connection. It does not offer mobile apps, offline lessons or a streak system. If you want to learn Spanish or French, study on your phone during a commute, or rely on game mechanics to keep a daily habit, Duolingo covers that and PromGee does not.

What does Duolingo do better?

• Many languages, with every course free according to its App Store listing.
• Mobile-first, game-like lessons that make short daily practice easy.
• Practice across speaking, reading, listening and writing, not only grammar.
• A family plan for Super that covers up to five other people.

Where does PromGee fit better?

• Grammar-specific practice: choose the exact category you need to work on.
• An AI explanation for every answer, in 40+ languages.
• A one-time payment rather than a subscription.
• Learning progress and settings stored locally on your PC, with no account required.

Who should choose which?

Choose Duolingo if you are starting a language from the beginning, learn mostly on your phone, want a free option, or are motivated by streaks and game elements.

Choose PromGee if you already study English, keep making the same grammar mistakes, want to know why an answer is right, and practice on a Windows PC.

Use both if you like Duolingo for daily habit and want deeper grammar practice on the side. Start with the free English grammar checker to find the mistakes you make most often.