Comparison

Systematic FYI vs SD Primer

Price, ratings, monetisation and update history for both apps, side by side β€” with what reviewers say about each.

Head to head
About

Systematic FYI

Features
Read full description

Review key concepts with a simple system design flashcard app for your system design interview. This app includes three sets of flashcards focused on common interview questions, patterns, and tradeoffs. It’s designed to help you build intuition for system design interviews at FAANG companies like Google, Meta, Amazon, and other top tech firms. Ideal for software engineers preparing for interviews or brushing up on architecture fundamentals. No extra features or distractionsβ€”just system design flashcard practice. Privacy Policy: https://www.systematic.fyi/privacy Terms of Service: https://www.systematic.fyi/terms

About

SD Primer

Features
Read full description

Think like a staff engineer β€” five minutes a day. SD Primer turns system design mastery into a daily habit. Answer today's questions, debug a broken architecture with your hands, and build the instincts that tech interviews (and real jobs) demand. YOUR DAILY RITUAL β€’ Daily Quiz β€” five sharp multiple-choice questions on scalability, databases, caching, queues, and trade-offs, with clear explanations for every answer β€’ Focus Practice β€” we detect your weakest topics and serve extra reps exactly where you need them β€’ Streaks, XP, and levels that make consistency effortless HANDS-ON ARCHITECTURE LABS Don't just read about system design β€” fix it. Each lab drops you into a live incident: drag components onto the canvas, wire the fix, defend your reasoning, and get scored with strengths and trade-offs. LEARN AI & ML FROM FIRST PRINCIPLES A structured 64-lesson course, one daily read at a time: from the origins of AI through neural networks, transformers, and how to actually use LLMs well β€” written for software engineers, no math degree required. AND EVERY DAY β€’ Coding pattern drills β€” name the algorithm behind the problem β€’ Workplace mastery lessons β€” the soft skills that get engineers promoted β€’ Curated engineering news and daily tips β€’ Your progress, visualized: topic strength, consistency calendar, achievements SD PRIMER PRO Unlock custom quizzes, labs, and pattern sessions tuned to your goals, plus higher daily limits. Subscriptions auto-renew unless cancelled at least 24 hours before the end of the period; manage anytime in your App Store account settings. Privacy Policy: https://sdprimer.com/privacy Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Start today. Your future self at the whiteboard will thank you.

Screenshots

Systematic FYI3 screens
SD Primer4 screens

Verdict

The call

The clearest difference is iOS requirement: Systematic FYI at 15.1 against SD Primer's 17.0. On price, update cadence, ads and in-app purchases there is nothing between them.

Scored on Price Β· Rating Β· Positive reviews Β· Number of ratings Β· Update frequency Β· Ads Β· In-app purchases Β· Monetization Β· Best chart rank Β· Devices Β· Requires iOS

CostPrice Β· In-app purchases Β· Ads Β· Monetization

Both are free to download. Systematic FYI sells 1 in-app purchase, starting at $3.99 per month and SD Primer sells 2 in-app purchases, starting at $9.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly every 5 days. The most recent releases landed on September 20, 2026 and August 4, 2026 respectively.

Scorecard1 real difference Β· 5 level
Systematic FYI versus SD Primer: the parameters behind the verdict, then further details
ParameterSystematic FYISD Primer
PriceFreeFree
Update frequencyEvery 5 daysEvery 5 days
AdsNoNo
In-app purchasesYesYes
DevicesiPhone, iPad, iPod β€” betteriPhone, iPad
Requires iOS15.1 β€” better17.0
Further details β€” not scored
Size30 MB20 MB
Age rating4+4+
DeveloperWilliam PrinErnesto Hilvano

In-app purchases

1 purchases

Systematic FYI

Subscriptions1
  • Systematic Premium$3.991 Month
2 purchases

SD Primer

Subscriptions2
  • SDPrimer Pro$9.991 Month
  • SDPrimer Pro$99.991 Year

Questions

Is Systematic FYI free?
Systematic FYI is free to download, with in-app purchases available.
Is SD Primer free?
SD Primer is free to download, with in-app purchases available.
Do Systematic FYI or SD Primer have ads?
Neither Systematic FYI nor SD Primer shows ads.
Which is updated more often, Systematic FYI or SD Primer?
Systematic FYI ships an update every 5 days, and SD Primer every 5 days. Most recently, Systematic FYI was updated on September 20, 2026 and SD Primer on August 4, 2026.

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