Some words
are meant to last.
A fast, private place to jot things down — ideas, notes, the day as it happens — kept in order and encrypted on your device. And when some words deserve to last, send them forward: to your future self, or the people you love.
• Opens in a second• End-to-end encrypted• Works offline• Web today · macOS, iOS soon
— 01 / Quick capture
Open it.
Write it down.
Done.
Posthum opens straight onto a blank page, in under a second. Jot the idea, the note, the thing you’ll forget by lunch. It lands on your timeline in order — searchable, taggable, and encrypted before it’s stored. Every entry is a private draft until you decide otherwise: the fleeting thoughts can stay fleeting, and the ones that matter get a flick of the wrist toward whoever should read them, now or years from now.
- ↑ swipeSeal it for later — for your future self, or someone you name
- · defaultPrivate. Encrypted on this device. Nobody else, ever.
- ↓ swipeDelete. Empty drafts delete themselves.
Today · 9:12 pm
“I was wrong about her, and the apology I owe is older than I want to admit.”
↑ sealed for may 2042
Today · 2:40 pm
Idea: the newsletter, but as letters that arrive a year late. #ideas
— 02 / Privacy as architecture
We can’t read
your notes.
Not now,
not ever.
Every entry is encrypted on your device, with a key only you hold. Our servers only ever see ciphertext — opaque, useless, ours to keep but never to read. If they leaked tomorrow, an attacker would get gibberish.
“If you forget your passphrase and lose your recovery key, even we cannot bring your vault back. That is the price — and the proof — of zero-knowledge.”
- You write
- “Auggie laughed at his own joke for the first time today.”
- Then
- ⊙ PBKDF2-SHA256 ×600,000 derives a key from your passphrase⊙ It wraps a random 256-bit vault key (Argon2id planned)⊙ AES-256-GCM encrypts each entry in the browser, fresh IV every time
- We store
- 7f2e a9c1 4d8b 0f33 e612 88ad 2145 09bc 6d7e f028 aa54 6b91 3e8c 0d22 7b14 ec90 5841 cd6f 9123 ae07 d2b8 4e35 1f9a 8c6e …
Don’t take our word for it — the journal’s security headers let you verify it can’t phone home.
— 03 / Time capsules
Write today.
Open it in five years.
Seal any note for a date you choose — a year out, or forty. Until then it stays hidden, stamped with the month it opens. When it is time, we email you a one-time link. Until then, even we don’t know what’s inside.
— 04 / Letters that travel through time
Decide what
lives on.
And who
gets to read it.
Mark a note as legacy. Choose who receives it, and when. A birthday in 2042. Your daughter’s wedding. A morning, after you’re gone, when someone needs to hear from you again.
Released only after people you choose confirm it, with a waiting period and your right to cancel built in. Curated by you, not auto-inherited like a hard drive.
For Ana — on our anniversary
● May 17, every year, until you say otherwise
3 pages
annual
To Auggie, on his 18th
● Aug 03, 2039
11 pages
once
To Mom, when I'm gone
● Legacy · trusted contact named
2 pages
legacy
— 05 / Why I'm building this
A note from the
person making it.
placeholder · 3:4 ]
I lost a friend when we were young. For years afterward I’d go back and read the small, ordinary things he’d left online, and somehow they mattered. It was the closest thing I had to him still being in the room.
It made me think about what I’d want to leave for the people I love, and how little we have for it. Not a will, not a hard drive to sift through — the actual thing. A letter for my daughter on the morning of her wedding. A note for my partner on a hard Tuesday years from now. The quiet days, kept the way they happened.
Posthum is the journal I wanted to exist.
— Doug
Founder
— 06 / Pricing
Free to keep.
Pay to carry it
across devices.
No ads. No trackers. No upsells. The cloud sync subscription pays for the storage that holds your encrypted vault, and the runway that keeps it there.
Planned pricing
Local
Forever free
One device. Yours, completely.
$0/forever
- Fast capture — notes, ideas, the day, in order
- Search, tags and mood
- Local sealed letters to your future self
- End-to-end encryption
- Encrypted backup export (.posthum) and plain Markdown
- Bring-your-own-key reflection
Cloud sync · planned
Carry it with you
Every device. Delivered on time.
$4/month · or $39/year
- Encrypted sync across your devices
- Sealed letters delivered by email on the open date
- Letters to people you name
- Legacy delivery, on your terms
Your words are never locked in: export everything, any time, in a format you can open without us.
Write something
worth keeping.
Join the waitlist for v1.