DET Practice Review: AI-Powered Duolingo English Test Prep, Examined

If you have applied to a university abroad in the last couple of years, you have probably run into the Duolingo English Test (DET): cheaper than IELTS or TOEFL, taken at home, scored fast. The catch is that its question types are oddly specific — "Read Aloud," "Write About the Photo," "Speak About the Photo" — and you cannot really wing them. That gap is what tools like DET Practice are built to fill.

DET Practice is a web platform dedicated entirely to DET prep: a large question bank, full-length mock exams, AI scoring for the speaking and writing tasks, and a set of courses. It is run by a UK company, AITOGETHER LTD, registered in Covent Garden, London. Below is what holds up under a closer look, and where I'd tell a prospective buyer to slow down and verify for themselves.

What you actually get

The core is volume. DET Practice advertises 18,000+ practice questions spanning every DET task type, updated, it says, daily, with model high-scoring answers and explanations attached. For a test where familiarity with the format is half the battle, a deep, well-tagged bank is the single most useful thing a prep tool can offer, and this is the part of the pitch that is easiest to take at face value.

On top of the bank sit full-length mock tests. These are framed as adaptive and close to the real exam, with AI-generated scores and a detailed evaluation report delivered within a few minutes of finishing. Mock-test access, worth noting, expires 90 days after purchase, so this is something to buy when you are actually in your study window, not months ahead.

The other headline feature is AI correction for the productive skills. For writing tasks ("Write About the Photo," "Interactive Writing," "Writing Sample") and speaking tasks ("Listen, Then Speak," "Read, Then Speak," and so on), the platform returns an AI score plus written feedback, with what it calls teacher guidance layered on. There is also a general-purpose "AI tutor" for grammar fixes, translation, and on-demand explanations, and a library of free courses on the speaking and writing sections built by ESL instructors.

The partnership claim, examined

DET Practice leans heavily on its relationship with Duolingo. It describes itself as part of the Duolingo English Test Global Partner Network, and that network is real — Duolingo does run an official partner program. Worth flagging, though: the site is not consistent about its own tier. The partner page is titled "DET Official Platinum Partner" and the comparison table lists "Platinum Tier," but a few paragraphs down on that same page, the FAQ calls it a "Gold-tier Partner." Both claims sit on one page. It does not undermine that a partnership exists, but if the exact tier matters to you, treat it as something to confirm against Duolingo's own partner directory rather than the marketing copy.

To the company's credit, it is more careful elsewhere. The homepage displays a wall of university logos — MIT, Harvard, Stanford and the like — but attaches an explicit disclaimer that these represent schools its users have applied to, "not endorsement by institutions." That is the honest way to use that kind of social proof, and it is good to see.

Pricing

At the time of writing, DET Practice runs a free tier (roughly 300 sample questions with limited feedback) and three subscription levels, all billed monthly but discounted if you commit to three months:

• Basic — $7.9/month (billed $23.7 per 3 months): 18,000+ questions and 10 AI corrections per month, but no mock tests.
• Plus — $15.9/month ($47.7 per 3 months): adds 3 mock tests per month and 60 AI corrections.
• Pro — $29.9/month ($89.7 per 3 months): unlimited AI correction and 10 mock tests per month.

Mock exams are also sold à la carte in packs (1, 3, 5 or 10 attempts), starting around $17.99, for people who only want a few realistic dry runs rather than a full subscription. There is also a member coupon for 10% off the actual DET exam fee, which you claim by contacting support.

The structure is sensible: the cheapest paid plan unlocks the bank, and you pay up as you need more AI feedback and mock attempts. Prices and quotas change, so check the live page before buying.

Where I'd be cautious

Two things keep this from being an unqualified recommendation.

First, the numbers are self-reported and not always consistent. DET Practice claims 400,000+ users and a 4.8/5 rating from "over 1,850 reviews" on its homepage, while the structured data behind its partner page lists 4.9/5 from 880 reviews. The success stats wobble too — one page says 95% of students who finish the full course hit their target, another says 99% of premium students do. None of this comes with a methodology, and all of the testimonials live on the company's own site.

Second, independent coverage is genuinely thin. Searching beyond the company's own domain turned up very little — no substantial discussion on Hacker News, and no body of third-party reviews on the usual software-review sites. That is not evidence of anything bad; plenty of useful niche tools fly under the radar. But it does mean you cannot easily triangulate the marketing against outside voices, so the prudent move is to lean on the free tier first and judge the question quality and AI feedback yourself before paying.

And on AI scoring specifically: the platform says its scores are "highly accurate" and "aligned with the DET scoring framework." That is plausible — DET prep tools generally model the rubric — but there is no way to independently verify how closely an AI estimate tracks your eventual official score. Use the predicted scores as a relative gauge of progress, not a promise of your test-day result.

Who it's for

DET Practice fits the test-taker who has a deadline, wants a large bank of realistic questions in one place, and values fast AI feedback on speaking and writing over a human tutor's slower, pricier attention. The free tier and à-la-carte mock packs make it low-commitment to try, and the genuinely multilingual interface (it ships in more than a dozen languages, including Indonesian, Japanese, Korean and Spanish) suits its largely international audience.

It is less suited to someone who wants certified, human-graded feedback, or who is uncomfortable acting on AI score estimates without an outside benchmark. For those, a tutor or an official Duolingo practice resource alongside it makes sense.

Bottom line

DET Practice is a real, actively maintained, fairly comprehensive prep platform from a registered UK company, and its core offering — a big question bank plus AI-scored mocks and corrections — is exactly what most DET candidates are looking for. Start on the free tier, verify the question quality and the AI feedback against your own sense of the exam, and treat the louder marketing claims (the partnership tier, the rating counts, the success percentages) as things to confirm rather than take as given. Used that way, it is a sensible addition to a DET study plan.

Sources consulted

• DET Practice homepage — features, the 400,000+/18,000+/40,000+ stats, the 4.8/1,850 rating, and the task-type lists for AI correction.
• DET Practice pricing page — plan structure, AI-correction and mock quotas, the 90-day mock expiry, and (rendered) the Basic/Plus/Pro and à-la-carte mock prices.
• Duolingo English Test Partner page — the AITOGETHER LTD company details, the Platinum-vs-Gold tier wording, the university-logo disclaimer, and the 4.9/880 / 95% figures.
• Hacker News (Algolia search) — confirmed there is essentially no independent discussion of this specific tool.
• Wayback Machine — confirmed the site is established and archived (closest snapshot April 2026).