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See the C100DEV examThe study partner who knows exactly where you're weak.
Winston · your AI study partner
Prep smarter, not harder. Blueprint-weighted readiness for every exam domain, an AI tutor who teaches instead of quizzing, and fresh questions in every format the exam uses. Sit the exam the day the numbers say you're ready.
Start free3 exams always free · no card needed
Microsoft · AWS · Google Cloud · CompTIA · Cisco · GitHub · MongoDB · HashiCorp · 33 certifications
- certifications
- 33
- vetted practice questions
- 52,695
- vendors
- 8
- exams always free
- 3
- hands-on lab
- 1
What's new
Meet Winston
Tell Winston what keeps tripping you up.
He teaches it, then drills it.
Tell Winston where you are struggling and he answers with a teaching card: plain language on what you are getting wrong and how to set it right, a real-world example, and a way to remember it. Then drill that exact topic in a three, five or ten question quiz, while it is still fresh.
Ask anything
Ask the way you would ask a tutor, in your own words. Winston already knows your exam, its blueprint and the questions you have missed on that topic, so the answer is written for you, not pulled from a generic article.
See it in the real world
Each card starts with a plain-language explanation, then sets out the distinctions the exam tests, side by side in a table when that makes them clearer. A real-world example follows, so the concept sticks as a story rather than a definition.
Remember it
Each card ends with a How to Remember aid: a mnemonic, a rule of thumb or a mental picture, whichever fits the concept. The exam trap is called out too: the wording that points to one answer, and the option that pairs two things that cannot go together, a favorite trick of the exam.
Then drill it
One click starts a short drill on exactly that topic, three, five or ten questions, so what you just reviewed is tested while it is fresh. Miss one and it joins your miss queue.
Keep every answer
Every question you ask is kept, with the card Winston wrote for it, so you can open any explanation again later: the week before the exam, or the moment that topic trips you up again.
Click to enlarge
The diagnosis
Winston's Study Brief:
your misses, explained, with the fix.
Ask Winston is where you bring a question. The Study Brief is where Winston brings one to you: a personalized analysis of your weak spots, built from your recent misses and the subdomains still under target. Need it from a different angle? Hit Regenerate and he takes another pass at the same weak spots.
The gap, named
One line that says what your misses have in common, so you know what you are actually weak on, not just which questions you got wrong.
What to nail down, per area
For each weak area, the specific facts and distinctions to lock in, written from the questions you missed.
The exam tip
How the exam tends to dress the concept up, and what to map it to when you see it. Regenerate the brief whenever your misses change.
The scoreboard
Know when you're ready.
Readiness is weighted by the exam blueprint, not by how many questions you clicked. Every domain sits in a band: Ready, Almost there, Needs work, and a domain clears to Ready at 80% accuracy, the same bar everywhere. Winston's Corner reads your whole history and tells you what to fix next, how your momentum is trending, and what needs the most work.
Ready, domain by domain
Every domain on the exam's home page shows its share of the exam, how many of its subdomains are ready, and your accuracy. Open one and each subdomain is read against the same target: 15 questions answered and 80% accuracy, Ready, Almost there or Needs work. One click drills the subdomains that are not there yet.
Winston's Corner
Up to 13 cards on your exam home, depending on how much history you have: what to drill next, where you stand by domain, how close you are to Ready, and what your last sessions showed. Three are shown here.
The miss queue: every wrong answer, until you clear it
Every miss waits
Every question you get wrong joins the queue, grouped by subdomain, with its miss count beside it and the repeat offenders counted.
Cleared by two in a row
Nothing leaves until you have answered it correctly twice in a row, so a lucky guess does not clear it.
Bookmarks are separate
My Queue holds the questions you save to come back to. Practising them never moves your readiness; it only updates each question’s own tally.
Try one
A real question, right here.
Pick an answer and submit. Winston's explanation shows exactly what the exam was testing.
From AZ-900 · Microsoft Azure Fundamentals
Sample 1 · Concept
Your company has multiple Azure subscriptions. You need to apply governance policies and role-based access control consistently across all of the subscriptions at once. Which Azure feature should you use?
Pick one, then submit.
One loop, every exam
Learn it. Drill it. Simulate it.
Know when you're ready.
Learn
Study brief, Ask Winston. Understand the domain before you are tested on it.
Drill
Smart Drill on your weak domains, Flash Recall for the facts that slip.
Simulate
A timed exam sim with the item types the exam uses, case studies where the exam has them.
Verify
Readiness bands per domain, and a pass badge when you report a pass.
Every format the exam uses, not just multiple choice.
Concept
Single-best-answer knowledge checks.
Scenario
Apply concepts to a real-world situation.
Ordering
Drag steps into the right sequence.
Multi-select
Pick every correct option — no partials.
Matching
Connect terms to definitions.
Flashcards
Quick-study term recall.
Case study
Multi-part scenarios, several linked questions.
Hands-on labs
Run real commands — e.g. live MongoDB.MongoDB
Not a fixed bank
Questions that are generated and checked,
then rotated and retired.
Generated fresh
Written to the exam's current blueprint, domain by domain.
Checked by a team of AI agents
Every question, its answer key and its explanation are reviewed by the agent team before it is served.
Rotated by exposure
The least-seen question in a topic is served first, so the same one does not come round twice in a row.
Retired when the exam changes
Replaced when the objectives change, and when a question has been served too many times.
A fixed bank goes stale the day it is written. Yours does not.
The library
Every exam, the same depth.
33 certifications across 8 vendors, each built to the same standard: the official domains and their weights, questions in every format the exam uses, Winston's teaching cards and Study Brief, and readiness per domain against the same 80% target.
- Access one exam, two at a time, or the whole library.
- AZ-900, CLF-C02 and CDL stay free on every plan.
- Each exam code below opens its page and tells you what it tests, who it is for and its domains, with a sample of every format.
- certifications
- 33
- vendors
- 8
- always free
- 3
- MongoDB1 exam
- HashiCorp1 exam
Teams
Bring the whole team up to ready.
Buy a block of seats, invite by email, and every teammate gets the same Preppio: fresh questions in every format, Winston, and readiness per domain. You get the view that shows who is ready.
Seats in blocks of 5, 10 or 20
Larger blocks cost less per seat. Billed per seat, monthly or annual.
Each seat is the two-exam plan
A teammate picks two exams and gets the free trio on top. Any seat can be upgraded to All Access.
A manager view
Readiness per member, per exam, in one grid, so you know who is ready to sit and who needs another week.
14-day free trial. No sales call.
Start the trial in the app, invite by email, and teammates are linked the moment they sign in.
Why we built this
We built Preppio for the gaps the prep services leave. How you prepare, and how deep the material goes, including the certs where credible prep barely exists.
Take MD-102. Beyond the official learning path there was almost nothing, so we built our own. One of our first testers studied 30 days on Preppio and walked in cold: a solid pass on the first attempt.
One tester's result, not a promise.
i.The method gap
Most prep is static: a bank to memorize or a video to watch. Preppio is a study partner who reads your misses and goes after them.
ii.The depth gap
Every domain of every exam, with explanations that teach, not just a key.
iii.The forgotten exams
We go deep where good practice is hard to find, and we keep going when the exam changes.
Pricing
Take one exam, two, or the whole library.
Start free, upgrade when you want more. Prices in USD.
Free
Always free
$0 /mo
no card
- AZ-900, CLF-C02 and GCP-CDL, free forever
- A starter allowance of generated questions and drills
- A taste of Winston reviews and Ask Winston
- No card
Single
One exam
$19 /mo
billed monthly
- One exam of your choice
- The free trio included on top
- A monthly AI allowance that renews with billing
- Every format the exam uses
Dual
Two exams at once
$36 /mo
billed monthly
- Two exams of your choice
- The free trio included on top
- A larger monthly AI allowance
- Every format the exam uses
All Access
Every exam
$55 /mo
billed monthly
- Every exam in the library
- The largest AI allowance
- Readiness tracked across every exam
- Every format the exam uses
Teams
Seats come in blocks of 5, 10 or 20, and larger blocks cost less per seat. Each seat is the two-exam plan: a teammate picks two exams and gets the free trio on top, and any seat can be upgraded to All Access. You get the manager view: readiness per member, per exam, so you know who is ready to sit and who needs another week. Billed per seat, monthly or annually, after a 14-day free trial.
Team 5
5 seats
$34 /seat/mo
per seat, billed monthly
$170 a month for all 5 seats
Team 10
10 seats
$31 /seat/mo
per seat, billed monthly
$310 a month for all 10 seats
Team 20
20 seats
$28 /seat/mo
per seat, billed monthly
$560 a month for all 20 seats
Cancel any time. Personal plans: first-payment refund within 14 days, see Terms.
FAQs
The things people ask before they start.
How are the questions made, and who checks them?
Every question is generated from the exam's published objectives, then passed through an agentic review team that checks the accuracy, the answer key and the explanation before it is served. Questions rotate by how often they have been seen, and they are retired when the exam's objectives change.
Is this an exam dump?
Absolutely not. Every question is original content, generated by our systems from the exam's published objectives and written in our best gauge of the vendor's voice, so the tone is familiar when you sit the exam. Nothing is copied from any exam, and questions are retired when the objectives change.
What does Winston do with my answers?
Winston reads your attempt history to teach the concept you missed and to pick what to drill next; that is the whole use. We do not sell customer information and we do not share it with advertisers, period. The AI providers we use and what they receive are listed in the Privacy Statement, and there are no advertising trackers on this site or in the app.
What is free, forever?
Three exams: AZ-900, CLF-C02 and GCP-CDL, with a starter allowance of generated questions, drills, Winston reviews and Ask Winston. There is no card to enter and no trial clock; the free exams stay free, and every paid plan includes them on top.
Can I cancel? What about refunds?
Cancel any time from your profile; access runs to the end of the paid period and nothing is deleted. If your first personal subscription is not for you, email support within 14 days of that first payment for a full refund, once per customer; renewals and Team plans are not covered. The Terms have the details.
Which exams do you cover?
33 certifications across 8 vendors: Microsoft, AWS, Google Cloud, CompTIA, Cisco, GitHub, MongoDB and HashiCorp. Each exam has its own page in the exam library, with the domains it tests and a sample of every question format. New exams ship as they are ready, and the library keeps growing.
Does it work on my phone?
Yes. Preppio is an installable web app: add it to your home screen and it opens full screen with its own icon, like any other app. There is nothing to download from an app store and nothing to update: every load gives you the current version, with the latest features, and your progress is the same on every device you sign in from.
Can my team use it?
Yes. Buy seats in blocks of 5, 10 or 20, invite teammates by email, and see readiness per member, per exam, in the manager view. Each seat is the two-exam plan, any seat can be upgraded to All Access, and every Team plan starts with a 14-day free trial. The Teams page has the prices and the trial terms.