Last updated: October 2025
This evaluation set out to answer a simple question: which AI language app actually builds speaking ability? Over nine months, three AI-powered language apps were tested head-to-head — Duolingo, Speak, and Lingvist — three months each, 30 minutes daily, learning Spanish from roughly the same intermediate starting point.
The results were not quite what the initial expectation was.
Duolingo: The One Everyone Knows
Duolingo has over 100 million monthly users, and there’s a reason for that. The gamification is addictive. Streaks, hearts, leaderboards, XP. It turns language learning into a mobile game. I maintained a 90-day streak without much willpower, which says something about the design.
The AI Features in 2026
Duolingo has added significant AI features since the early days. The big ones:
Duolingo Max: This adds two features: “Explain My Answer” and “Roleplay.” Explain My Answer gives you a conversational breakdown of why you got something wrong, in plain language instead of a grammar rule dump. Roleplay puts you in simulated conversations: ordering at a café, asking for directions, making small talk at a party, even negotiating prices at a market.
The Roleplay feature is the standout. During testing, a 10-minute conversation with an AI barista about coffee preferences showed it correcting grammar in context without breaking the flow. “You said ‘Yo quiero un café con leche grande’ — that works, but a more natural way would be ‘Un café con leche grande, por favor.’” That kind of contextual correction is exactly what you get from a human tutor. (See also: No-Code AI Tools That Actually Work: Build Apps)
What Duolingo does well:
- Consistency. The gamification genuinely keeps you coming back. No other tool has ever stuck with a language app this long
- Breadth of content. The course covers vocabulary, grammar, listening, reading, and (with Max) speaking and conversation
- The progression system is well-designed. It introduces new concepts gradually and reviews old ones at smart intervals
- Available in 40+ languages. If you’re learning something less common like Welsh or Hawaiian, Duolingo might be your only app option
Where Duolingo falls short:
- The free version is frustrating by design. Limited hearts mean you can’t make mistakes without waiting or paying. It feels punitive
- Most exercises are translation-based. You spend a lot of time translating sentences you’d never actually say (“The bear drinks beer” is a real Duolingo sentence)
- Speaking practice is limited even in the Max tier. You’re mostly tapping and typing, not talking
- After three months, I could read Spanish much better but still froze up in real conversations. The app trains recognition more than production
Pricing: Free with ads and heart limits. Super Duolingo is $12.99/month or $83.99/year (removes ads, unlimited hearts, progress tracking). Duolingo Max is $29.99/month or $167.99/year (adds AI features). Family plans available. They frequently run promotions (I got Max for 50% off on Black Friday).
Speak: The Conversation-First App
Speak takes the opposite approach from Duolingo. There are no translation exercises, no matching games, no typing. Everything is voice-based. You talk, the AI listens, and it responds. It’s designed to get you speaking from day one.
How Speak Actually Works
Each lesson starts with a short video introducing a phrase or concept. Then you practice saying it, first in isolation, then in increasingly complex sentences, then in a free-form conversation with the AI tutor.
The AI speech recognition is impressive. It caught pronunciation errors that Duolingo’s speech recognition missed entirely. When the tester kept saying “pero” (but) when meaning “perro” (dog), Speak specifically drilled on the rolled R until it was right. It was annoying and effective.
The conversation mode is where Speak shines. Unlike Duolingo’s scripted roleplays, Speak’s conversations are genuinely open-ended. The AI responds to what you actually say, asks follow-up questions, and gently corrects errors without derailing the conversation. After a 5-minute conversation about weekend plans, it delivered a detailed breakdown: pronunciation score, grammar errors, vocabulary suggestions, and fluency rating.
What Speak does well:
- Speaking confidence. After three months, I could actually hold a basic conversation in Spanish. This is the one thing the other apps didn’t achieve
- Pronunciation feedback is the best in this review set. It uses visual waveforms to show you exactly where your pronunciation differs from native speakers
- The curriculum is practical. Lessons focus on real situations: ordering food, making appointments, having small talk, expressing opinions
- No gamification pressure. No streaks, no leaderboards. Just learning. Some people will miss the motivation; the evaluation found it refreshing.
Where Speak falls short:
- Limited language selection. As of early 2026, Speak offers English, Spanish, French, Italian, Japanese, and Korean. If you want Mandarin or Arabic, look elsewhere
- No reading or writing practice. It’s purely oral/aural. If you need to read or write in your target language, you’ll need a supplementary tool
- The free content is very limited — basically a demo. You need the paid plan to get real value
- Grammar explanations are minimal. Speak teaches through pattern recognition and repetition rather than explicit grammar instruction. This works for some learners but frustrates others
Pricing: Free trial with limited lessons. Premium is $13.99/month or $99.99/year. There’s no family plan. Compared to a conversation tutor on iTalki ($10-25/hour), it’s a bargain if you use it daily.
Lingvist: The Data-Driven Approach
Lingvist is the least known of the three, and that’s a shame. It was built by a physicist from CERN who applied machine learning to vocabulary acquisition. The core idea: learn the words you’re most likely to encounter, in the order that maximizes retention.
The Lingvist Method
Lingvist’s AI builds a model of your vocabulary knowledge and serves you exactly the words you need to learn next. It uses spaced repetition (like Anki) but with adaptive algorithms that adjust to your personal forgetting curve.
The main exercise is fill-in-the-blank within real sentences. You see a sentence with a missing word, hear the audio, and type the answer. It sounds simple — and it is — but the algorithm behind which sentences you see and when is sophisticated.
What Lingvist does well:
- Vocabulary acquisition speed. Vocabulary gains were higher in three months with Lingvist than with either of the other apps. The adaptive algorithm is genuinely effective
- The sentences are pulled from real-world sources (news articles, literature, podcasts, everyday speech), so you’re learning words in natural context
- Course customization. You can create custom word lists for specific needs like travel vocabulary, business Spanish, medical terminology, or exam prep
- The statistics dashboard shows your learning curve, estimated vocabulary size, predicted retention, and daily progress trends. As a data nerd, I loved this
- It’s fast. A 15-minute session covers 30-50 words. No fluff, no animations, no celebrations. Just learning
Where Lingvist falls short:
- It’s essentially a vocabulary trainer. Grammar, speaking, listening comprehension, and conversation are not covered in any meaningful way
- The interface is utilitarian. If you need gamification to stay motivated, Lingvist will bore you
- Limited to English, Spanish, French, German, and Russian. The course depth varies: Spanish and French are full; Russian is thinner
- No speaking practice at all. You’re reading and typing, never talking
- The free tier limits you to a small subset of words. The full experience requires a subscription
Pricing: Free tier with limited vocabulary. Premium is $9.99/month or $79.99/year. Cheapest of the three paid options.
Three Months Later: Real Results
Here’s what actually happened to Spanish proficiency after nine months of testing:
After Duolingo (months 1-3): Reading simple Spanish texts, understanding slow spoken Spanish, translating basic sentences, and picking up common phrases in context all improved. But holding a conversation remained difficult. Vocabulary was decent but passive; words were recognized but couldn’t be produced on demand.
After Speak (months 4-6): Conversational ability jumped dramatically. A 15-minute conversation with a Spanish-speaking colleague drew the comment that pronunciation was “surprisingly good.” But vocabulary was limited to conversational topics, and reading ability didn’t improve.
After Lingvist (months 7-9): Vocabulary expanded significantly. Reading Spanish news articles and understanding 80-90% of the words became possible. But without speaking practice, conversational fluency actually declined from where Speak had gotten it.
The takeaway is obvious: no single app does everything well.
Our Recommendations
If you’re a complete beginner: Start with Duolingo (even the free version). It builds foundational vocabulary and grammar in a structured, low-pressure way. Use it for 2-3 months to build a base, then switch.
If you want to actually speak: Speak is the clear winner. No other app builds conversational confidence this effectively. If your goal is to travel and communicate, this is your app. Pair it with Lingvist for vocabulary building.
If you’re intermediate and want to expand vocabulary: Lingvist. The adaptive algorithm is the most efficient way to grow your word bank. But use it alongside a speaking tool. Vocabulary without practice is just trivia.
The ideal combo: Lingvist for daily vocabulary (15 min) + Speak for conversation practice (15 min), three to four times per week. Total cost: about $24/month. That’s less than a single hour with a human tutor, and the result is daily practice instead of weekly.
If budget is tight: Duolingo free + Language Reactor (a free Chrome extension that adds subtitles and vocabulary tools to Netflix and YouTube in your target language). Not as effective as the paid options, but genuinely useful and completely free.
The honest truth: apps alone won’t make you fluent. They’ll get you to a solid intermediate level. After that, you need real human conversation, whether that’s iTalki tutors or language exchange partners or actual immersion. But these apps make the journey to intermediate faster and more enjoyable than most traditional self-study methods in this comparison set.
Related guide: AI tools for teachers and classrooms. Related guide: AI tutoring platforms compared.