SumizAI vs Capacities

What Capacities is

What Capacities is

Capacities is a German note-taking app built around the idea of objects instead of folders — every note, idea, or question becomes its own object with properties and relations to other objects. The company was founded in 2021, is headquartered in Berlin, and stores data on encrypted servers within the EU.

Key features

Bidirectional linking connects related objects in both directions, and a graph view visualizes the entire network of connections between them. A built-in AI assistant helps summarize and query gathered content, and a rich text editor supports the formatting typical of other notebooks. Sync works across every device — Mac, Windows, Online, Android, iPhone, Android Tablet, Linux, iPad — so notes stay available regardless of the platform a user is on.

Who it's for

Capacities appeals to people who feel constrained by traditional folder structures and want to think in terms of connected objects — ideas, questions, projects — combining the flexibility of a note network with database-like structure. Teams and researchers building an extensive, interconnected knowledge base get a tool matched to that style of work.

Use cases

In practice, Capacities works well for building a personal knowledge base with clearly defined object types, managing tasks tied to specific projects or source notes, and visually exploring the connection network through the graph view when you need to rediscover forgotten links between ideas.

Pricing and business model

The free plan offers unlimited notes and objects with 5GB of media storage. The first paid plan, with task management, an AI assistant, and calendar integrations, costs €10.99 a month (€8.99 a month billed yearly) and adds unlimited storage plus priority support.

Limitations and what to watch for

The object-and-type-based model requires a different mindset than a simple text notebook, so setting up your own object types initially can be time-consuming. Advanced features like task management and the AI assistant are reserved for the paid plan.

AI notes as a distinct object type

Capacities doesn't integrate directly with an external AI model for holding a conversation, but pasting an assistant's answer as an ai notes entry and giving it its own object type with relations to other notes is a natural part of the system. Such an ai notes entry automatically shows up in the graph view next to thematically related objects, making it easier to find later.

European data storage as a deliberate choice

The decision to keep data exclusively on servers within the EU, rather than defaulting to US infrastructure, answers growing demand from European users and companies for solutions aligned with local data-privacy regulations.

What's worth checking before choosing

Before deciding, check whether the free plan's 5GB storage limit is enough for your needs, and whether an object-and-relations model actually fits how you organize knowledge.

Bottom line

Capacities is a solid choice for people who think in terms of connected objects rather than flat folders, with European data storage as an added advantage. Anyone who wants ai notes from AI conversations to land in the system automatically, without manually assigning an object type, will find a better-fitting tool elsewhere.

Comparison with SumizAI

Capacities and SumizAI differ in how they organize content. Capacities builds a network of connected objects with relations defined by the user, with an optional AI assistant for summaries. SumizAI generates these notes directly from a conversation with an AI model — question, answer, Markdown file in the user's vault, with a title and place in the table of contents assigned automatically, on your own API key to one of seven providers. Anyone who wants to build a knowledge base of manually defined objects and relations will pick Capacities; anyone who wants these notes from AI conversations to be created automatically will find SumizAI the better-fitting tool.

That is our reading of the record. For AlternativeTo's own wording, see its page for Capacities — the facts above were read on 2026-08-16.

Capacities in depth

Objects instead of folders

Capacities is a note application built on a single structural decision that reaches into everything else it does: the unit of storage is not a document in a directory but a typed object. A person, a book, a meeting, a project or an idea each becomes an entity with its own properties, and those entities link to one another. The result is a network rather than a tree. The vendor's argument is that hierarchical filing was designed for machines in the 1980s and forces a decision — which folder does this belong in — that costs more attention than it saves, especially when the same note is legitimately about three things at once.

Object types are user-defined and created as needed, so the schema grows with use rather than being designed in advance. Backlinks show every incoming connection, and a Related Content feature scans the vault for places where a topic was written about but never explicitly linked, surfacing associations the writer made without noticing. The daily note serves as the inbox: capture first, structure later or never. The company is emphatic that no configuration, no memorised Markdown syntax and no plugin ecosystem is required to get value, which is a deliberate contrast with the more tinker-friendly tools it competes against.

Who makes it, and how they fund it

The developer is Capacities Labs GmbH, based in Germany and supported by Media Lab Bayern. The team describes itself as small and bootstrapped — no investors, no board — funded entirely by subscriptions, and treats that independence as a product feature rather than a footnote: the argument is that answering to users instead of shareholders keeps the roadmap aligned with the people who actually use the thing. The company also states plainly that it builds for individuals, not teams, and explicitly rejects collaboration features and enterprise scope as things that would distort the product.

That positioning is unusual enough to be a genuine differentiator, and it is reflected in the pricing structure, where one of the three tiers exists primarily so that users who want to fund the project can pay more than the product costs.

The free tier is a real product

Capacities Basic costs nothing and is not a trial. It includes unlimited spaces, objects and blocks, unlimited custom object types, synchronisation across every device, full-text search over all content, offline support, complete import and export, view-only sharing of notes with others, and capture from WhatsApp, Telegram, Twitter or email. The one meaningful cap is media: five gigabytes of uploads in total, then a hundred megabytes per month afterwards. The company has published a written promise that the core product will remain free, framing access to knowledge tools as a principle rather than a marketing stage.

What Pro adds

The paid tier is organised around four capabilities. The AI assistant is scoped to the vault rather than the open web: you can hold a conversation about an individual note, ask it to summarise, translate, critique your writing or continue a thought, and it answers from what is actually in the note. Its most distinctive trick is auto-fill — create a book object and the assistant populates author, genre, publication year, summary and themes; create a film and it fills in director, cast, runtime and synopsis. It also proposes tags, collections and properties for approval rather than applying them silently.

Queries are saved, dynamic views built from combinable conditions across dates, tags, properties and collections: all books rated four stars or higher, tasks due this week, articles tagged with a topic from the last three months that remain unread. Results can be embedded into any page to build dashboards, and variable queries change with context — opening a person shows every note involving them, opening a project shows its related tasks.

Calendar integration pulls scheduled events next to daily notes and tasks, turns events into objects with attendees, agendas and follow-ups attached, and surfaces prior meetings and open items before a meeting starts. Task management keeps tasks inside the notes they belong to, creatable from a note, the command palette or mobile, and linked to projects or people rather than living in a separate application. Pro further adds Related Content, Smart Search, unlimited media uploads under a fair-use policy, table formulas, a curated icon set, API access, and extensions including Raycast and Web Highlights.

The third tier, Believer, contains everything in Pro plus early beta access to major features, and is sold openly as a way to fund the team's independence. AlternativeTo records the price band as ten to thirteen US dollars per month; the vendor's own pricing page renders its figures dynamically and shows a sixteen percent reduction for annual billing, with Believer quoted as a starting-from price. A free Pro trial is available in the app without a credit card.

Platforms, formats and getting your data out

Coverage is broad: macOS, Windows, Linux, the web, iOS, iPad, Android and Android tablets. Alongside the object model the editor supports Markdown and WYSIWYG editing, LaTeX, code formatting, live preview, mentions and file tagging, spell checking, a graph view, calendar and kanban views with subtasks and recurring tasks, and dark mode. The interface is localised into English, German, Dutch, Portuguese, Hungarian, Italian, French and Spanish. Two-factor authentication is available on the account.

The company makes an explicit anti-lock-in commitment: full export to standard formats at any time, on the stated principle that leaving should take your knowledge with you. Data sits in certified European data centres under GDPR with industry-standard encryption. This does not amount to end-to-end encryption — the AI features operate server-side on note content — but the jurisdiction and export guarantees are concrete.

Reception, and the recurring criticism

Capacities has the strongest community signal of any product in its bracket examined here. AlternativeTo shows forty-six likes, three comments and a rating of 4.9 out of five from eight ratings, with a hundred and thirty-one alternatives listed against it — a crowded category. The App Store rating stands at 4.26 as of July 2026, Product Hunt shows 4.8 across 198 reviews with a Product of the Day award, and the vendor reports more than fifty thousand users and a Discord community above ten thousand.

Users on AlternativeTo praise the handling of images inside notes and gallery sharing, its suitability as a personal wiki and journal, and its orientation toward personal rather than business use; one commenter calls it the best Notion alternative they have found. The consistent criticisms are two. The mobile application is noticeably weaker than the desktop one, and several users say so directly. And the product is described as a power user's app — the object model rewards people willing to think about how they think, and is likely to feel like overhead to someone who wants a place to jot a list.

Two further limits deserve naming. There are no team or organisational plans, by design, so a group cannot adopt it collectively. And the AI, queries, calendar and task features — the parts that make it competitive with Notion — all sit behind the subscription, so the free tier, generous as it is, is a different product from the one the marketing describes. Someone comparing this against SumizAI is comparing a complete personal knowledge system with a narrower tool; the overlap is limited to the fact that both process text you supply.

Product page: capacities.io

What SumizAI is

A note-taking application built around a conversation with an AI model. You ask a question, the answer streams back, and the answers worth keeping become Markdown notes — filed into a vault that is a folder on your own disk.

A vault is a directory holding base.md, a generated table of contents up to six levels deep, and a notes/ folder with one .md file per note. Before a note is written it is checked against the ones already there, so the fourth note about the same idea gets merged instead of added. Links between notes are ordinary Markdown links to files that exist.

The model is never ours: you bring your own API key to one of seven providers — Anthropic, OpenAI, Gemini, Groq, OpenRouter, a local Ollama or your own server — and pay that provider directly. A question sends the table of contents plus at most five relevant notes within a 24,000-character budget, and the app shows you which five it used.

Every answer kept this way becomes one of these ai notes, ready to search again months later without hunting back through old chats.

Side by side

Where they differ

• AlternativeTo's description of Capacities does not mention an AI model. That is the whole starting point in SumizAI: you have a conversation with a model on your own API key, and the answers worth keeping become notes without you filing them.
• Capacities is freemium: there is a free tier and a paid one, and the line between them is the thing to read before committing. SumizAI has one plan at a dollar a month, so there is no feature held back for a higher tier — and an unpaid account still opens and exports every vault it already has.
• AlternativeTo's description of Capacities does not mention Markdown, so check what format your notes end up in before you fill it up. SumizAI writes standard .md files to a folder you picked, and an unpaid account can still export all of them.
• Capacities is described in terms of linking notes together. SumizAI links them too, but deliberately without a syntax of its own: a link is an ordinary Markdown link, [Title](file-name.md), and the model may only point at a file that actually exists. There are no wiki-style [[…]] links to lose on export.
• Both are run from the EU: SumizAI's operator is registered in Poland and the servers are in Germany.

Which one to pick