Which is the best Duolingo English Test prep platform for you?
Choose PrepEx if you want to connect individual task feedback, full mocks and your next study session. Try Arno if you want unlimited free questions and a first free mock. Consider DETPractice if a large question bank is your priority. Start with Duolingo’s own free practice test to establish a baseline before buying a preparation plan.
The useful question is what you need after your next attempt. More questions help you practise different topics. A full mock helps you rehearse pacing. Detailed feedback should help you change a particular answer. A subscription is useful when it gives you something you will actually use between now and test day.
In this article, DETPractice means the service at detpractice.com. The phrase “DET practice test” can also mean a mock from any provider, including Duolingo’s own practice test.
PrepEx vs Arno vs DETPractice: free practice, feedback and mocks
Free questions, free grading and free full tests are separate offers. Check all three before deciding that a platform covers your study plan.
| What you need | PrepEx | Arno | DETPractice |
|---|---|---|---|
| Free task practice | One free Practice Hub item in each of 13 task families. A free account can grade two tasks per UTC day. | Unlimited questions across task types. | 300+ questions across task types. |
| Full mock tests | Ten full-length mocks, all requiring DET Pro. | First mock free; further unlimited mocks with a premium subscription. | Mock access and allowances depend on the selected plan. |
| Writing and speaking feedback | Free account: rubric scores and a concise focus plan. Pro adds detailed evidence from your response, history and recommendations. | Advertises AI feedback and detailed mock reports. | Advertises AI correction; check the plan’s correction allowance. |
| Study support | A rolling seven-day plan, saved attempts and dashboard review; Pro adds deeper analysis. | Personalized plans, a course and vocabulary tools. | Question bank and study tools; 18,000+ questions advertised for premium practice. |
| Before paying | Choose 7, 30 or 90 days. All are recurring DET subscriptions; Petra voice credits have a separate allowance. | Check the account’s current subscription offer and feedback access. | Check the current price, duration, mock allowance and correction limit together. |
Sources: PrepEx plans and mock catalog; Arno’s platform description and mock offer; DETPractice’s free/premium comparison and plan table. Question counts are provider claims, not our audit of every question.
Arno’s free question allowance is broader than PrepEx’s free Practice Hub allowance. PrepEx’s reason to make your shortlist is the practice-and-review workflow. Try the feedback before deciding whether you need Pro.
Which DET practice test should you take first?
Start with the official Duolingo practice test. Duolingo says it is free to repeat after creating an account, takes about 45 minutes and returns an estimated score range. It also uses adaptive difficulty. That makes it a useful starting point when you want experience with the test provider’s own practice. See Duolingo’s practice-test explanation.
For a third-party mock, inspect the report as well as the test player. Can you return to the answer you gave? Can you distinguish a missed listening detail from a writing problem? Does the report point you toward a task you can practise next?
PrepEx’s ten mocks use different private question sets, with 35 timed tasks across all 13 task families. Allow about an hour. Selected tasks use PrepEx’s internal difficulty routing, and the saved report includes feedback and a practice estimate. All ten require DET Pro.
PrepEx estimates are not official DET scores. PrepEx does not reproduce Duolingo’s scoring model, adaptive engine or proctoring. Its Speaking Sample records audio, while the official sample includes video; learning-mode practice may use AI-generated images. Review the real-test setup requirements separately.
We have not established which commercial platform predicts official scores most accurately. A fair accuracy comparison would need results from the same learners, comparable preparation conditions and a published method. Use the score guide to understand what an estimate can and cannot tell you.
How do you compare AI writing and speaking feedback?
Look for feedback that identifies something in your response and gives you a usable correction. A score and a longer rewritten answer are not enough to show you what to practise next.
- Check the evidence. Does the feedback quote the sentence, missed detail or part of your spoken answer it is discussing?
- Check the reason. Can you understand why a change improves relevance, grammar, clarity or development?
- Make one revision. Apply the advice yourself. A useful explanation should transfer to a new response.
- Return to the attempt. Check whether your plan saves the answer and feedback you need to review later.
What would useful feedback change here?
Illustrative learner sentence: “I prefer studying in a library because it is good and helps me more.”
“Use better vocabulary” leaves most of the work unexplained. A more useful comment identifies the vague words good and helps me more, then asks what specifically makes studying easier.
Possible revision: “I prefer studying in a library because the quiet helps me finish a reading assignment without checking my phone.”
The revision supplies a reason and a concrete effect. Your next step is to add a relevant example in your own words. This is an illustration written for this article, not a competitor’s output, a live grading result or a response to memorize.
For speaking, listen to your recording alongside the comments. Separate language feedback from recording problems. A transcript can help you notice repetition, but it does not show how clearly you pronounced a word or where you paused. A pronunciation claim needs evidence from the audio.
Start with the public PrepEx Writing Sample to inspect writing feedback, then use the speaking task guide to choose an appropriate spoken task. Review the actual feedback you receive against the checklist before upgrading.
On September 12, 2026, we submitted an original 194-word demonstration response through the public Writing Sample without signing in. The report showed separate Content, Coherence, Grammar and Vocabulary sections, each with evidence from the response and a next step. Its coherence comments identified our transition into a counterargument; its grammar comments pointed to a conditional sentence. This checks the feedback workflow on one example, not scoring accuracy or a typical learner result.
The public preview displayed a limit of two AI grades per IP in a 24-hour window. That allowance is separate from the signed-in free Practice Hub limit.
How much do PrepEx, Arno and DETPractice cost?
PrepEx’s public DET prices are US$9.99 for 7 days, US$19.99 for 30 days and US$29.99 for 90 days. Each renews automatically for the same billing period until canceled. These are preparation subscriptions; an official DET booking is separate. See the current PrepEx pricing page for the offer before checkout.
All three PrepEx durations unlock the same DET Pro library, ten mocks, unlimited standard grading and detailed feedback. Petra voice practice uses a separate allowance: 1,400 credits per 7 days, 6,000 per 30 days or 18,000 per 90 days. “Unlimited grading” does not mean unlimited voice tutoring.
We could not verify a numeric public subscription price for Arno in the pages reviewed. DETPractice’s public pricing page listed plan features, but its amounts did not display in our check. For those services, follow Arno’s account link or DETPractice’s pricing page and check the offer shown to you. We have not declared a cheapest platform from incomplete price data.
Compare the amount payable before your test date, the renewal date and the number of feedback sessions you expect to use. A short subscription can suit a near-term test; longer access only has value if you will use it. Check cancellation terms before starting any recurring plan.
How to use a DET prep platform in your first week
Choose one platform for your daily practice and keep the official practice test as a separate reference point. Repeating the same preparation response can improve that answer without proving that you can handle an unfamiliar prompt.
- Start: take the official practice test and write down the tasks that felt difficult, alongside its estimated range.
- Practise: pick one weak task family. Complete an attempt, review it and write down one change to make.
- Transfer: try a new prompt with the same focus. Check whether you made the change without copying a model answer.
- Rehearse: when you are familiar with the tasks, complete an uninterrupted mock and review where time pressure affected your work.
In PrepEx, use the task library to find the relevant practice, then the rolling seven-day study plan to organize your next sessions. If you only need free familiarization, stay with free resources until you can name the extra help you need.
Questions about PrepEx, Arno and DETPractice
Can I take a full PrepEx DET mock for free?
No. All ten PrepEx full mocks require DET Pro. Free individual-task practice is available separately, including one free Practice Hub item in each task family. See the mock catalog.
Is Arno free for Duolingo English Test preparation?
Arno advertises unlimited free task questions and a first free full mock. Further mocks and advanced features are part of its paid offering. Check the access included in your account. Sources: Arno platform and mock page.
Is DETPractice free?
DETPractice advertises 300+ free questions. Its larger question bank and AI correction are advertised as premium practice features; plan allowances vary. See its free/premium comparison and pricing table.
What is a good Arno alternative?
Shortlist PrepEx if you want to test its task-feedback and study-plan workflow, or DETPractice if you want to explore its advertised question bank. Compare a sample attempt and the current plan limits against your needs; neither is automatically a better fit for every learner.
Which DET mock test has the most accurate score?
This comparison does not establish an accuracy winner. Start with Duolingo’s own practice test for the provider’s estimated range. Third-party scores, including PrepEx practice estimates, are not certified DET results and should not be treated as a guarantee.
Do these platforms cover Interactive Speaking?
All three list Interactive Speaking among their practice task types. Check how the version you try handles prompt playback, response timing and follow-up questions. The PrepEx Interactive Speaking guide explains the task and opens matching practice.
Will buying a DET preparation plan guarantee 120 or 130?
No platform in this comparison can be recommended as a guaranteed route to a particular official result. Use feedback to improve your responses and check the exact score requirement set by your institution or program.
Should I buy several DET prep subscriptions?
Start with one. Add another only when you can identify a missing resource you will use. Spending your study time comparing scores across several platforms can leave less time for reviewing and improving your answers.
How this comparison was prepared
The PrepEx DET team compared public offers for free access, mock tests, feedback, study support and price on September 12, 2026. PrepEx descriptions were checked against its current practice, pricing and guide pages, with one anonymous Writing Sample submission to verify the public feedback workflow. The feedback checklist and teaching example are original editorial material. We did not purchase every competitor plan or run a controlled scoring benchmark, so this is a feature-and-fit comparison, not a ranking based on paid product trials.
Sources are linked beside the claims they support. Public offers can change; check the provider’s current plan before paying. PrepEx is the publisher and has a commercial interest in its own subscription. Recommendations here are based on the needs described, without star ratings or claims that a paid tool can guarantee an official score.
Complete the free public Writing Sample, read the feedback and decide whether it helps you make a specific improvement. If it does, compare PrepEx’s access options.