How to Build an App Like Notion

The blocks-based editor is the content model that makes everything else possible. Every piece of content is a block: paragraph, heading, bulleted list, numbered list, to-do item, toggle, code block, image, video embed, divider, callout, quote. Blocks can be nested -- a toggle block contains child blocks, a column block contains side-by-side child blocks. Users reorder blocks by dragging the handle to the left of each block.

The slash command is the primary creation mechanism. Typing "/" opens a menu of block types filtered as the user types. Creating a new block type, embedding content from an external tool, or inserting a database all happen through slash commands. This reduces the need for a complex toolbar and keeps the interface clean.

Markdown shortcuts accelerate the writing experience: typing "## " at the start of a line converts it to a Heading 2 block, "- " creates a bullet point, "```" opens a code block. These are standard expectations from users who have used Markdown-aware editors.

The open-source editor frameworks (Tiptap, Prosemirror, Slate.js) provide a solid foundation for the blocks model and handle the hard parts of rich-text editing: selection behavior, undo/redo, keyboard shortcuts, and browser compatibility. Using one of these as a base saves 3-4 weeks compared to building from scratch.

Notion's database feature -- its "killer feature" -- is a flexible schema system where properties are defined per database and can be changed without a migration. Each database is a collection of pages. Each page has properties: text, number, date, select, multi-select, checkbox, URL, email, phone, relation, rollup, and formula. Property types can be changed and new properties added at any time.

The same database can be viewed as a table (spreadsheet-like), a kanban board (pages as cards grouped by a select property), a gallery (pages as cards with a cover image), a calendar (pages positioned by a date property), and a list (compact vertical list). Each view is a different rendering of the same underlying data.

Relations link pages across databases: a task relates to a project, a project relates to a client account. Rollups aggregate properties from related records: count of open tasks per project, total budget across linked projects. Formula fields compute values from other properties using an expression evaluator that supports arithmetic, text functions, and date math.

Building the full database system -- all property types, all view types, relations, rollups, and formulas -- is the most time-intensive part of the platform. Plan 8-10 weeks of backend engineering for the full system. An MVP might launch with table and kanban views only, adding gallery, calendar, and formula fields in a second cycle.

Real-time collaboration lets multiple users edit the same page simultaneously. Presence indicators show who is currently viewing or editing a page -- a colored avatar or cursor positioned at their location in the document. Changes appear on all connected clients within milliseconds without a manual refresh.

The technical foundation is WebSockets: persistent connections between each client and the server that deliver updates instantly. The conflict resolution layer handles the case where two users edit the same block at the same time. The two dominant approaches are Operational Transforms (OT) and Conflict-free Replicated Data Types (CRDTs). CRDTs are generally preferred for new builds because they handle offline editing and late-joining clients more gracefully, but they require more upfront architecture work.

Comments and mentions are closely related: a user can select text in a block and add a comment thread. Mentioning another user with @name sends them a notification and creates a link to the comment. Resolved comments are archived but remain accessible in the comment history.

Real-time collaboration is the most complex component on this list. It adds 4-6 weeks to the engineering timeline and requires careful testing across concurrent editing scenarios, network interruptions, and reconnection behavior. If your MVP timeline is tight, single-user editing with page-level locking (one editor at a time) is a viable simplification that can be upgraded to real-time collaboration in a later cycle.

Permissions determine who can view, comment on, or edit each page and workspace. Notion's permission model has three levels: workspace-level (applies to all content in the workspace), page-level (overrides workspace defaults for a specific page), and inherited (child pages inherit the parent page's permissions unless overridden).

Access roles typically include: full access (create, edit, delete, share), edit (create and edit content but not manage permissions), comment (add comments but not edit content), and view (read-only). Guest access allows users outside the organization to be invited to specific pages without becoming full workspace members.

For multi-tenant SaaS products, workspace isolation is a hard requirement: users in one workspace must not be able to see or access content in another workspace, even if they share the same underlying database. Row-level security or strict schema separation enforces this isolation at the data layer, not just the application layer.

SSO integration (SAML 2.0 or OIDC) with providers like Okta, Azure Active Directory, and Google Workspace is standard for enterprise deployments. SSO integration also enables automatic user provisioning and deprovisioning: when a user is added or removed from the identity provider, their access to the workspace is updated automatically.

Workspace platforms are most useful when they connect to the other tools a team uses. Embed support lets users paste a URL from an external tool -- a Figma design, a Google Doc, a GitHub pull request, a Loom video -- and have it render as an interactive embed inside a page block rather than a plain link.

A public API lets external tools read and write workspace content. Other products in the team's stack can push data into the workspace (a new task created in Jira appears as a page in a Notion database) or pull data out (a weekly report exports workspace data to a Google Sheet). The API follows REST conventions with authentication via API keys or OAuth.

Webhook support lets external tools be notified when workspace content changes: a page is created, a database row is updated, a comment is posted. Webhooks enable automation without polling -- the workspace pushes events to the destination rather than the destination checking for changes.

For vertical platforms, the most valuable integrations are the two or three tools that define the user's existing workflow. A legal workspace integrates with the firm's matter management system. An engineering workspace integrates with the team's code repository and deployment pipeline. Depth in the right integrations beats breadth in generic ones.

Full-text search across all pages and databases the user has access to is the feature that makes a workspace platform reliable as a system of record. Without good search, users lose confidence that the content they stored is findable. With good search, the workspace becomes the default starting point for any question -- the team's institutional memory.

Search needs to be fast (results within 200 milliseconds) and accurate (the most relevant results ranked at the top). A search index (Elasticsearch or similar) updated as pages are created and edited provides the necessary performance. For multi-tenant platforms, the search index must enforce permissions so users cannot discover content they do not have access to through search.

The quick switcher -- a keyboard shortcut (Cmd+K or Ctrl+K) that opens a search-as-you-type modal for jumping to any page or database -- is the primary navigation mechanism for power users. Building a workspace without a fast quick switcher is a significant friction point for users who move between pages frequently.

Sidebar navigation with nested pages and a breadcrumb trail at the top of each page completes the navigation system. Users need to be able to browse by structure (hierarchical sidebar) and by keyword (search). Both modes are necessary; neither alone is sufficient.

We build the blocks-based editor using Tiptap or Prosemirror as the foundation, extended with the specific block types your platform needs. Standard block types (paragraph, heading, list, code, image, table, divider, callout) are included. Vertical-specific block types -- a legal matter reference block, a clinical protocol block, a deployment runbook block -- are added on top.

The slash command menu, markdown shortcuts, drag-and-drop reordering, and keyboard navigation are built and tested across the browsers and devices your users will use. The editor is designed to feel fast and responsive even on pages with hundreds of blocks.

We build the flexible database engine with the property types and view types your platform requires. For an MVP, we typically start with table and kanban views plus the core property types (text, number, date, select, relation). Gallery and calendar views, formula fields, and rollups are added in a second cycle once the data model is proven.

The schema is user-defined and stored flexibly so new property types can be added without a database migration. Multi-tenant data isolation ensures each workspace's data is stored and queried independently. The database engine is designed to support filtering, sorting, and grouping at the view level without requiring a full-table scan for large datasets.

We build the WebSocket server, the conflict resolution layer (CRDT-based for most projects), and the presence indicator system that shows who is viewing and editing each page. The collaboration infrastructure handles offline editing, reconnection behavior, and large documents with many concurrent editors.

Comments and mentions are built on top of the real-time layer: users can comment on specific blocks, mention teammates, and receive notifications when they are mentioned or when a thread they are watching receives a new reply. Comment history is retained and accessible even after threads are resolved.

We build the permission system with workspace-level, page-level, and inherited permissions. Role definitions (owner, editor, commenter, viewer, guest) are configurable to match your organization's access model. Invite links with configurable permission levels let users share specific pages with people outside the workspace.

SSO integration with your target identity provider (Okta, Azure AD, Google Workspace, or a custom SAML 2.0 provider) is built for enterprise deployments. Automatic user provisioning via SCIM is added when your customers require centralized lifecycle management. Audit logs record who accessed or modified what content and when.

We build full-text search with an Elasticsearch-backed index, filtered by the user's current access permissions. The quick switcher (Cmd+K) is built for speed -- results appear within 150 milliseconds of the first keystroke.

The public API follows REST conventions with API key and OAuth authentication. Webhooks deliver real-time event notifications to external tools. For your highest-value integrations -- the one or two external tools your users depend on most -- we build direct integrations as part of the initial platform. The API and webhook infrastructure supports adding further integrations without platform changes.

We build the admin dashboard covering member management, role assignment, workspace settings, SSO configuration, billing integration, and usage analytics. For regulated-industry platforms, we add the compliance tooling: audit log viewer, content export for legal hold, and data retention policy configuration.

The admin dashboard is built as a first-class interface. Workspace administrators need clear controls over membership, permissions, and data -- not a settings page that was designed last.