Seal your word.
Turn promises, agreements, and payment plans you make with another person into a digital, device-signed agreement receipt. No notary, no passwords, in minutes.
For iOS and Android — sign-up takes 30 seconds, no password, phone verified.
Car sale — 2018 Golf
Ali Yılmaz · Mehmet Kaya
- Price: ₺485,000
- Handover: May 15, keys + registration
- Payment: cash, wire transfer
Receipt code
SEAL-3F8A2D1C
Audit hash
a4f1…c2b9
From word to seal, in five steps.
It's not complicated. Pair up, write what you agreed, send, seal. Faster than driving to a notary or downloading a contract template.
- 01
Pair up
Join the same session as the other person. Share a code, both type it in — you connect in seconds.
- 02
Create the receipt
Pick a ready-made template (loan, service, sale, rental) or start blank. Briefly write the subject.
- 03
Write the items
Enter the details of your agreement line by line: what, how much, when. Use AI suggestions to speed up complex cases.
- 04
Send to the other party
They see the receipt in their "Incoming" tab. They approve, suggest a revision, or reject. You see their proposal and accept or revise in turn.
- 05
Seal it
When both sides approve, the receipt is sealed. Device-based digital signatures bind both parties to a PDF you can download anytime.
Good contracts need good math.
You're writing something sensitive. What you write should not slip away, change without trace, or be impersonated. The cryptography under Seal exists exactly for that. Not marketing — code, auditable.
Device-based signing
Every device generates its own Ed25519 keypair. The private key never leaves your phone — the server only sees your public key and verifies your signatures.
Ed25519 · libsodium
Tamper-evident audit chain
Every action on a receipt (create, send, revise, seal) is chained to the previous link with SHA-256. Removing or altering any record in the middle is mathematically detectable.
SHA-256 append-only
Passwordless, phone-verified
We store no passwords. Phone verification uses Twilio WhatsApp with a 6-digit OTP. Codes are stored as salted SHA-256 hashes, compared in constant time, and expire in 5 minutes.
WhatsApp OTP · Salted SHA-256
Minimum data
No email, no password, no address. Only your phone (E.164) and an optional display name. Phone numbers are masked on the public verification page.
PII minimization
End-to-end TLS
All connections (app → API, OTP, push) over HTTPS. MongoDB Atlas database is encrypted at rest, access restricted by IP allowlist.
TLS 1.3 · Atlas at-rest
Public verifiability
Every sealed receipt has a unique code. Anyone (including the parties) can verify the signatures, hash, and audit chain at getseal.app/verify/{code} independently.
Public verifiability
Legal note
Seal produces a strong, digitally signed evidence document — but it does not replace qualified e-signatures (e.g. Turkish NES, EU eIDAS QES). For high-value or formal transactions like deeds and corporate filings, combine Seal with a notary or qualified e-signature. For the vast majority of everyday agreements, Seal stands on its own.
Frequently asked.
Can I edit a receipt after it has been sealed?
No. A sealed receipt freezes its content. If you want to prepare a new version, you can send a 'Suggest revision' on top of it — if the other party accepts, it becomes v2, but v1 still stands as a record. The audit chain proves this.
What if the other party doesn't respond?
The receipt stays in "Pending" status. You can nudge them, cancel the receipt, or let it sit indefinitely. As long as it isn't sealed, no binding outcome is created.
Is it free to use?
Yes — the beta is free. At launch we plan a generous free tier for personal use and a Pro plan for advanced features. Beta users will get early-access perks.
Add weight to your word.
Beta version, free. Open your phone, sign up, send your first receipt in 60 seconds.
getseal.app · getsealapp.com