DoCube vs SecondBrain Pro
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
DoCube
This app transforms reading into knowledge retention with features like multi-tab browsing, precise document navigation, and versatile annotation tools. It supports various formats and converts highlights into flashcards for effective memorization and review.
- Multi-tab reading for multiple documents
- Precise document positioning and history navigation
- Support for PDF, EPUB, Markdown, and web pages
- Six annotation tools including highlights and notes
- Cross-document linking for knowledge networks
- Automatic flashcard creation from highlights
- AI-enhanced card generation
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DoCube is a multi-format reader and personal knowledge base built for deep reading. Bring PDFs, EPUBs, local videos, web snapshots, Markdown, and organized scanned documents into one library. Annotate, link, search, translate, export, and review while you read or watch. Your materials are not merely stored—they gradually become knowledge you can retrieve, connect, and remember. 【Deep Reading Across Formats】 DoCube supports PDFs, EPUBs, local videos, offline webpages, Markdown, and parsed documents. Whether you work with research papers, ebooks, web articles, course videos, lectures, interviews, or your own Markdown notes, you can read, watch, and manage them together in DoCube. 【Deep Study for Video】 Import local videos and study courses, lectures, and interviews as deeply as documents. DoCube can read embedded subtitles and, on supported devices, generate subtitles for videos that do not have them. Search subtitles; switch between original, translated, and bilingual views; annotate subtitles; use chapter outlines, playback speeds, and A/B looping. Open a search result, annotation, or chapter to return to the exact moment, turning video into knowledge you can retrieve, connect, and review. 【Multi-Tab Reading】 Open multiple documents and videos in tabs, just like a browser, and switch quickly between materials. Read a paper, compare references, watch a course, or return to where you left off without losing context. 【Annotations and Notes in Context】 Use highlights, underlines, strikethroughs, quotations, links, and Markdown notes directly on source text or at a precise location in video subtitles. Your thinking stays connected to its context. 【Link Materials Together】 DoCube can link an annotation in a document or video to a precise location in another resource. Connect scattered chapters, paragraphs, webpages, video clips, and notes into your own paths through knowledge. 【Search What You Have Read and Watched】 Search not only titles and body text, but also video subtitles, highlights, quotations, links, notes, and cards. Anything you have read, watched, marked, or written can help you find the right material again. 【Keep Reading in Other Languages】 Translate selected text while reading. Some document types support full-document translation and translated exports, while videos support subtitle translation and original, translated, or bilingual display. Read foreign papers, webpages, ebooks, and course videos without constantly switching tools. 【From Annotation to Review】 Turn important content from documents and videos into review cards. Flip cards, mask cards, and review plans bring what you have read and watched back at the right time, instead of letting it disappear after you finish. 【Export and Sync】 Export document content and translations to common formats, including bilingual versions. DoCube is available on iPhone, iPad, and Mac, with iCloud sync and local Wi-Fi transfer. Ideal for: - People who read research papers and professional materials - Learners organizing PDFs, EPUBs, webpages, Markdown, and videos - People who study long-term with course, lecture, and interview videos - Deep readers who want annotations, notes, and review in one loop - Anyone building a personal knowledge base instead of merely collecting files The free version manages up to 5 documents and lets you experience the core reading and knowledge-management workflow. Upgrade to Pro to remove the document limit and build an unrestricted personal library.
SecondBrain Pro
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Save a thought while you walk. Find a decision after a meeting. SecondBrain Pro is a voice-first memory app for iPhone and iPad, with an Apple Watch companion for capture from your wrist. Choose local storage or free iCloud sync. Optional Standard and Premium upgrades are one-time purchases. CAPTURE AND RECALL Record a thought or type a note. Organize ideas, learnings, tasks and decisions with tags. Search saved memories by text and dates, or ask AI Chat about your memories when a supported AI provider is available. START FREE Voice and text capture, ordinary search, local storage and iCloud sync are included in Free. On-device AI chat is available on supported Apple Intelligence devices. No SecondBrain account is required. iCloud needs your Apple account and available iCloud storage. STANDARD: OPTIONAL ONE-TIME UPGRADE Add premium speech playback voices, expanded memory context, JSON/Markdown export, and backup and restore tools. iCloud sync is already included in Free. PREMIUM: YOUR OWN BACKEND AND MCP Includes Standard capabilities and adds a connection to your own Cloudflare Worker backend, backend semantic search, API access and MCP integration for compatible tools such as Claude Code and Cursor. This option requires your own Cloudflare account, deployed backend URL and API key. MCP also requires a bridge and compatible client. Cloudflare usage may incur separate charges. Local-only memories are not automatically available to external assistants. WHERE YOUR DATA GOES Local Only stores memories on this device. iCloud sync transfers them through your personal Apple iCloud account. The optional Cloudflare mode sends memories to your configured backend for storage and selected AI processing. Connected MCP clients handle data according to their own configuration and provider policies. Voice capture uses Apple's speech recognition and may use Apple servers. Microphone and speech recognition permission are required. Location context is optional. The app requests in-app consent for AI processing. AI REQUIREMENTS On-device AI chat uses Apple Foundation Models and requires iOS 26 or later, compatible Apple Intelligence hardware, Apple Intelligence enabled and an available model. Voice capture and ordinary search do not depend on Foundation Models. Premium users can configure cloud AI through their own backend. Check the App Store compatibility section before installing. PRICING Free download. Standard and Premium are optional one-time in-app purchases, with no SecondBrain subscription. See the purchase sheet for your regional price and currency. External backend services are separate. Developed in Switzerland by Heinrich Krupp. Product facts: https://secondbrain-pro.netlify.app/facts Support: https://secondbrain-pro.netlify.app/support
Screenshots
Verdict
The clearest difference is update cadence: DoCube at every 3 weeks against SecondBrain Pro's every 2 months. On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. DoCube sells 1 one-off in-app purchase and SecondBrain Pro sells 2 one-off in-app purchases. Whichever you choose, the download price is not the number that matters.
DoCube ships an update every 3 weeks, SecondBrain Pro every 2 months. Both last shipped on October 24, 2026.
| Parameter | DoCube | SecondBrain Pro |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (11 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 11 — better | — |
| Update frequency | Every 3 weeks — better | Every 2 months |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad, Mac — better | iPhone, iPad |
| Requires iOS | 17.0 | 17.0 |
| Further details — not scored | ||
| Size | 104 MB | 10 MB |
| Age rating | 17+ | 4+ |
| Developer | Hangzhou Wenxu Interactive Technology Co., Ltd | Heinrich Krupp |
In-app purchases
DoCube
- Full-platform Professional Edition$34.99
SecondBrain Pro
- Standard$7.99
- SecondBrain PREMIUM$17.99









