A second brain that shows its work.
Upload docs, voice notes and images, then ask. NullBrain answers with a citation to the exact source — or says “that’s not in your notes” instead of inventing one.
Free forever tier · No credit card · One-tap Google sign-in
ChatGPT guesses. NullBrain quotes.
Everything you save becomes something you can ask.
Not a chatbot bolted onto your files — a memory that cites itself, answers in your voice, and follows you into your editor, your chats and your meetings.
Answers with receipts
Every answer names the exact document, page or audio timestamp behind it. Tap the chip, jump to the source.
Your brain, inside your editor
One API key plugs your notes into Claude Code, Claude Desktop and Cursor via MCP.
✔ Connected
tools: search_notes · ask ·
add_note · get_digest
Honest when it doesn’t know
Below the relevance bar it stops and says so. It would rather refuse than invent a source.
A copilot that sits in on meetings
It listens in, surfaces the right note at the right moment, and when someone asks what your brain already knows, hands you the answer with its source.
Capture from anywhere
Forward to Telegram. Highlight in Chrome. Paste a YouTube link. Import a Notion page. Drop a PDF. It all lands in one brain.
Obsidian, mirrored
Sync your vault with one command. Edit a note and your brain updates itself, no duplicates.
Study mode
Your notes quiz you back — spaced-repetition flashcards generated from anything you’ve saved.
Drafts that cite themselves
Turn your notes into an email, post or report — grounded in your brain, every claim carrying its source. You edit; it never invents.
Chat with one document
Lock the conversation to a single doc and ask away — answers stay inside it, cited line by line.
Agent tools, opt-in
Let it use web search, page fetch and a calculator on hard questions. Off by default, always cited.
Teams with real walls
Shared team brains with roles and SSO/OIDC, walled off by row-level security the database itself enforces.
One API, signed webhooks
Automate everything over REST. Events arrive HMAC-signed, so you can trust the sender.
Your knowledge, rendered as a universe.
Hub concepts burn as suns; your notes orbit as planets. The map is yours alone and reloads exactly where you left it.
Live in the app — this one’s just a small system.
From brain dump to cited answer.
Capture
Drop PDFs, record voice notes, forward to Telegram, clip the web, sync Obsidian, paste a YouTube link, or push notes in over MCP and the REST API.
Constellate
Every chunk is embedded into your private galaxy and stamped with provenance — source, method and time you can audit.
Ask
A cited answer in seconds — by text or voice. Or an honest “that’s not in your notes.”
Private by architecture, not by promise.
It answers in your voice. Literally.
Record one short, consent-gated sample. Then any answer — and a daily podcast digest of your notes — can come back narrated by you. All of it on private hardware.
- Consent-gated cloning — your voice, only by you
- Daily podcast digest, read in your own voice
- Full-duplex voice loop with barge-in
“We built NullBrain because we didn’t trust our own AI notes. So we made every answer carry a receipt.”
The NullBrain team · building in public
Start free. Upgrade when your galaxy grows.
Pay only when you want your own voice — or a brain for your team.
Free
Your whole second brain, free
- Cited answers and honest refusals
- Docs, audio & YouTube capture
- Telegram bot & web clipper
- Galaxy map & study mode
- MCP + API key
Pro
Everything, plus your voice
- Everything in Free
- Voice clone — answers in your voice
- Daily podcast digest, narrated by you
- Meeting copilot & agentic retrieval
- Full-duplex voice loop
Team
A brain your whole team shares
- Everything in Pro
- Shared team brain, roles & invites
- SSO / OIDC + SCIM
- Priority support
Fair questions, straight answers.
Can anyone else see my notes?
No. Every tenant is isolated with database-enforced row-level security, your files are encrypted at rest with per-tenant keys, and our test suite proves tenant A cannot read tenant B, in both directions.
What happens when the answer isn’t in my notes?
NullBrain tells you so. It can optionally answer from general knowledge, but that answer is clearly labeled and carries no citation. It never pretends your notes said something they didn’t.
Is my voice clone safe — and can I delete it?
Cloning is consent-gated and only works with your own sample. The sample is encrypted and processed on a private machine, never a shared cloud. You can delete it any time, and deleting your account removes everything.
Do my notes train anyone’s model?
No. Your content is used to answer your questions, full stop. Nothing you upload is used for training, ours or anyone else’s.
Can I export everything and leave?
Yes. Your originals stay intact, the API exposes your library, and deleting your account permanently removes your documents, embeddings, voice profile and history.
What does free actually include?
The full second-brain loop: capture from docs, audio, Telegram, Chrome and YouTube, cited answers with honest refusals, the galaxy map, study mode, and an MCP/API key. Voice cloning and the podcast digest are Pro.
Your notes are smarter than you think. Ask them.
Set up in two minutes: sign in, drop a file, ask your first question.
Want first access to what’s next — mobile apps and new experiments?
No spam. Invites and ship notes only.
