SideBrain is a browser-based personal knowledge assistant and second brain. It lets you capture notes, organize them with collections and tags, import PDFs and YouTube transcripts, and query your knowledge base with AI for summaries, study guides, flashcards, and audio overviews.

Is SideBrain private?

Yes. SideBrain is local-first: your notes are stored in your browser's localStorage by default. AI features send only the relevant note context to the model to answer a question. No analytics on note content, no tracking of what you write.

Do I need an account?

No. SideBrain works without any sign-in. Optional Auth0 authentication is available for users who want to sync their vault across devices.

What file formats can I import?

SideBrain imports PDF, DOCX, and XLSX via drag-and-drop or file picker. It also imports YouTube video transcripts by pasting a URL. Imported documents are automatically summarized and tagged.

Which AI models does SideBrain use?

SideBrain runs through the Vercel AI Gateway, so it can use Gemini, GPT, and other frontier models with a single API key. Embeddings use OpenAI text-embedding models and are stored locally for semantic search.

Does SideBrain work offline?

Yes. SideBrain is a Progressive Web App with a service worker. You can read and edit notes offline; AI features resume when the network returns.

Can I import an Obsidian vault?

Yes. SideBrain imports Obsidian vaults by reading markdown files with YAML frontmatter and converting wiki-links. Folders become collections.

Does SideBrain support spaced repetition?

Yes. SideBrain supports Anki-style flashcards using `?::answer` syntax in any note. Reviews use the SM-2 scheduling algorithm and state is persisted locally.

Yes. SideBrain is free and open source. You bring your own Vercel AI Gateway API key (or OpenAI key for embeddings); SideBrain does not mark up usage, sell your data, or show ads.

How is SideBrain different from Notion or Obsidian?

Notion is cloud-based and tracks usage. Obsidian is local-only but does not have built-in AI grounded in your notes. SideBrain combines local-first storage with NotebookLM-style AI grounded retrieval, so the AI can answer questions and cite your notes without sending them to a third-party database.

Can I use SideBrain on mobile?

Yes. SideBrain is a Progressive Web App, installable on iOS and Android with offline support. A native Capacitor build is also available for App Store / Play Store distribution.

Does SideBrain have a public API?

Yes. SideBrain exposes a per-vault REST API secured with an API key for programmatic sync. See the `ApiServerModal` in the app for endpoints, curl examples, and key generation.

SideBrain — Personal AI Knowledge Assistant and Second Brain

Overview

SideBrain is a privacy-first, browser-based personal knowledge management (PKM) and second brain application. It runs entirely in your browser with local-first storage (localStorage) and optional cloud sync. SideBrain combines a fast markdown note-taking experience with retrieval-augmented generation (RAG) so you can ask questions of your own knowledge base.

Key Capabilities

Note-taking and organization

Markdown notes with bidirectional [[wiki-links]], backlinks, and block-level references.
Collections (Ideas, Learnings, Projects, Reference, Documents) and hierarchical tags.
Properties / YAML-style frontmatter with typed values (text, number, date, checkbox, list, tags).
Note templates with {{date}} variable substitution and built-in defaults.
Daily notes with streak tracking and habit parsing.

AI assistant (NotebookLM-style)

Streaming chat with retrieval over your notes and documents.
Source citations for every answer.
Auto-generated summaries with key points and suggested tags.
Two-host audio overview scripts for text-to-speech playback.
Notebook guides, study guides with quizzes, suggested questions, and multi-source synthesis.

Import and search

Drag-and-drop import of PDF, DOCX, and XLSX with automatic summarization and tagging.
YouTube URL import that fetches the transcript and creates a note.
Obsidian vault import (folders become collections, frontmatter parsed).
Full-text search, semantic search using OpenAI embeddings stored locally, and operators like tag:, collection:, is:pinned, has:link, and date ranges.

Visualization

Interactive knowledge graph (force-directed) with local and global views.
SVG mindmap showing connections between notes.
Canvas / spatial whiteboard with draggable cards and SVG edges.
Timeline, calendar, kanban, table, and stats dashboard views.

Study and review

Spaced-repetition flashcards using ?::answer syntax and the SM-2 scheduler.
Quiz-style study guides generated by AI.
Habit tracking parsed from daily-note checkboxes.
Pomodoro timer.

Rich content

KaTeX math rendering (inline $...$ and block $$...$$).
Mermaid diagrams in fenced code blocks.
Dataview-style inline queries that render filtered entry lists.
Footnotes, callouts (NOTE, WARNING, TIP, QUOTE), folding headers, embeds / transclusion.

Input, output, and portability

Voice input (Web Speech API speech-to-text) and text-to-speech output.
Audio recorder for voice memos embedded in notes.
Slash commands: /date, /time, /link, /table, /todo.
Export to PDF, EPUB, JSON, Markdown via Git, or as a static site ZIP.
Plugin architecture, custom CSS snippets, command palette, and workspaces.
Progressive Web App (PWA) with service worker for offline use; iOS and Android via Capacitor.

Privacy and data ownership

Notes are stored in your browser's localStorage by default. AI features only send the relevant note context to the model needed to answer your question. You can export the entire vault as JSON at any time and import it back. Optional Auth0 + Postgres (Neon) integration is available for users who want cloud sync, but it is not required.

How it compares

SideBrain combines the calm, focused interface of Bear with the bidirectional linking of Roam, the visual thinking of Heptabase, and the AI-powered source-grounded answers of NotebookLM — while remaining local-first and free.

Technology stack

React 19 + TypeScript + Vite
Vercel AI SDK and AI Gateway (Gemini, GPT)
OpenAI embeddings with cosine similarity
pdfjs-dist, mammoth, SheetJS for document parsing
KaTeX for math, Mermaid for diagrams, marked for markdown
Capacitor for iOS and Android
Vitest and React Testing Library for tests
Deployed on Vercel (static + edge functions)