Comparison

PDF AI vs Sigmy

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

Head to head
About

PDF AI

Features
Read full description

PDF AI transforms any PDF into powerful study materials using advanced AI. Whether you're a student, researcher, or professional, PDF AI helps you understand documents faster and study smarter. CHAT WITH YOUR PDFs Ask any question about your PDF and get instant, accurate answers with page references. The AI understands context across your entire document, so you can have natural conversations about complex topics. AI STUDY TOOLS Generate comprehensive study materials from any PDF with a single tap: - Summary: Concise overview with key points and page citations - Detailed Summary: In-depth analysis with headings, data, and conclusions - Study Notes: Organized bullet-point notes with key concepts - Flashcards: Interactive Q&A cards for active recall practice - Quiz: Multiple-choice questions with explanations to test your knowledge - Glossary: Key terms and definitions extracted from the document - Key Insights: The most important findings and takeaways MULTI-LANGUAGE SUPPORT Generate all AI content in 10 languages: English, Turkish, Spanish, French, German, Arabic, Chinese, Japanese, Korean, and Portuguese. OCR TEXT EXTRACTION Extract text from scanned PDFs and image-based documents using Apple Vision framework. Works offline with high accuracy. MULTI-DOCUMENT WORKSPACE Create workspaces to chat across multiple PDFs simultaneously. Perfect for research projects, exam prep, or comparing documents. PDF & IMAGE TOOLS A complete toolkit for document management: - PDF to JPG, Merge PDFs, Split PDF, Compress PDF, Rotate PDF - Image conversion: HEIC, PNG, JPG, WebP - Image resize, Images to PDF, TXT to PDF PRIVACY FIRST Your PDF files stay on your device. When you use AI features, only the text needed for your request is sent securely for processing, and we don't store your documents. SUBSCRIPTION INFORMATION PDF AI Premium unlocks AI chat with your PDFs, all AI study tools, PDF editing and signing. Subscription auto-renews unless cancelled at least 24 hours before the end of the current period. Payment will be charged to your iTunes Account at confirmation of purchase. Privacy Policy: https://pdfaiapp.github.io/privacy Terms of Use: https://pdfaiapp.github.io/terms

About

Sigmy

Features
Read full description

Sigmy is a fully on-device AI assistant. The language model, document search, and every piece of private text stay on your iPhone or iPad. No cloud. No account. No tracking. No training on your data. Ever. WHY SIGMY IS DIFFERENT • Runs a Google Gemma model locally on your device — no API keys, no subscriptions to external AI services, and no network round-trips that can leak your content. • Works offline, on a plane, in a tunnel, or in a sensitive workplace where cloud AI is banned. • Your documents, chats, and questions never leave your device. We cannot read them and neither can anyone else. WHAT YOU CAN DO • Ask questions about your PDFs, Word docs, text files, Markdown, and scanned images — every answer cites a tappable source passage. • Import documents by tapping +, scanning with the camera, capturing text from photos, pasting images, or sharing from any other app. • Compare two or more documents side-by-side — "what's different between these contracts?", "which proposal has better terms?". • See comparison answers as clean tables when the model formats them that way. • Tap suggested follow-up questions after each answer to dig deeper with one tap. • Extract events from any document straight to your Calendar — meeting dates, deadlines, travel itineraries. • Hands-free mode: have Sigmy read answers aloud in your choice of voice — fully on-device. • Dictate questions by voice and export chats as PDF, Markdown, plain text, RTF, or email. • Search your chat history to find past conversations instantly. • Full-text search across every document you've imported, with semantic ranking that understands what you meant. • Quick-prompt templates for executive summaries, action items, study outlines, and timelines. PRIVACY BY DESIGN • Optional Face ID / Touch ID unlock for the whole app. • Optional AES-GCM encryption of the document index at rest, sealed whenever you background the app. • Privacy manifest declares every iOS API we touch and why. • PII detection warns you before indexing credit card numbers or other sensitive identifiers. FREE TRIAL — 7 DAYS OF EVERYTHING Every new install gets a 7-day free trial with full Pro features: unlimited documents, extended memory window, and all advanced tools. No credit card required. SIGMY PRO After the trial, Sigmy Pro unlocks: • Unlimited document imports and queries • Extended memory window for long files • All advanced tools and future Pro features at no extra cost THREE WAYS TO SUBSCRIBE • Pro Monthly — $5.99/month after a 7-day free trial • Pro Yearly — $39.99/year after a 14-day free trial (saves ~50% vs monthly) • Lifetime Pro — one-time $79.99, permanent access, no renewals SUPPORTED DOCUMENT TYPES PDF, Word (.docx), plain text (.txt), Markdown (.md), Rich Text (.rtf), HTML, CSV, and images containing text (via on-device OCR). DEVICE REQUIREMENTS iPhone or iPad with sufficient RAM for on-device AI. Sigmy adapts memory settings automatically to your device. The language model (~3.4 GB) is included in the app — no separate download after install. Works fully offline once installed. — SUBSCRIPTION TERMS Sigmy Pro is an auto-renewable subscription. • Pro Monthly: $5.99 per month after a 7-day free trial. • Pro Yearly: $39.99 per year after a 14-day free trial. • Lifetime Pro: one-time $79.99 non-renewing purchase. Payment will be charged to your Apple Account at confirmation of purchase. Subscriptions renew automatically unless auto-renew is turned off at least 24 hours before the end of the current period. Your account will be charged for renewal within 24 hours prior to the end of the current period. You can manage and cancel your subscription in Settings → Apple Account → Subscriptions. Privacy Policy: https://www.sigmygroup.com/privacy Terms of Use: https://www.sigmygroup.com/terms

Screenshots

PDF AI4 screens
Sigmy4 screens

Verdict

The call

The clearest difference is update cadence: PDF AI at every 3 days against Sigmy's every 2 weeks. On price, ads, in-app purchases and device support there is nothing between them.

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

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

Both are free to download. PDF AI sells 2 in-app purchases, starting at $4.99 per month and Sigmy sells 3 in-app purchases, starting at $5.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

PDF AI ships an update every 3 days, Sigmy every 2 weeks. Both last shipped on October 31, 2026.

Scorecard1 real difference Ā· 5 level
PDF AI versus Sigmy: the parameters behind the verdict, then further details
ParameterPDF AISigmy
PriceFreeFree
Update frequencyEvery 3 days — betterEvery 2 weeks
AdsNoNo
In-app purchasesYesYes
DevicesiPhone, iPad — betteriPhone
Requires iOS17.017.0
Further details — not scored
Size34 MB3.2 GB
Age rating4+4+
DeveloperYusuf Omer EremSIGMY GROUP PTY LTD

In-app purchases

2 purchases

PDF AI

Subscriptions2
  • Premium Monthly$4.991 Month
  • Premium Yearly$29.991 Year
3 purchases

Sigmy

Subscriptions2
  • Pro Monthly7 Days trial$5.991 Month
  • Pro Yearly14 Days trial$39.991 Year
One-time1
  • Lifetime Pro$79.99

Questions

Is PDF AI free?
PDF AI is free to download, with in-app purchases available.
Is Sigmy free?
Sigmy is free to download, with in-app purchases available.
Do PDF AI or Sigmy have ads?
Neither PDF AI nor Sigmy shows ads.
Which is updated more often, PDF AI or Sigmy?
PDF AI ships an update every 3 days, and Sigmy every 2 weeks. Most recently, PDF AI was updated on October 31, 2026 and Sigmy on October 31, 2026.

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