LetsSeal

Seal and verify legal documents

Executed agreements, deeds, opinions, and court filings that prove their own authenticity, sealed to a published root, timestamped on the blockchain, and verifiable by any court, counterparty, or regulator. This is how a legal document stands on its own.

For solicitors, barristers, in-house counsel, paralegals, and ediscovery teams.

Open the app Developer docs
What a seal proves

Four guarantees, in law & legal

The executed version is the version

A changed clause, amount, or date, a single altered byte, fails verification instantly. What was signed is what verifies.

A named signer of record

Every seal names the firm that issued it, chaining to a published root. Not a vague “verified” badge, a specific certificate.

Fixed in time

An OpenTimestamps proof on the blockchain pins the moment the document existed, decisive for deadlines, priority, and which version came first.

Checked by anyone

Opposing counsel, a court, or a notary confirms the proof at a permalink, free, and standing on public infrastructure rather than on us.

How it works

From your file to a proof anyone can check

The same pipeline every time. The seal and the timestamp travel with the file, so the proof is self-contained.

Your file
Your signed PDF
Seal
Signed over every byte · PAdES
Anchor
Blockchain timestamp + public transparency log
Proof page
A permanent /d/… link travels with the file
Anyone verifies
Free, public, offline-capable, for anyone
The proof travels inside the file. Verification stands on the published root, the transparency log, and the blockchain, so a court, a bank, or a counterparty can check it independently, forever.
Step by step · the web app

Seal it in the app, no setup

  1. 1

    Sign in as your firm

    Open app.letsseal.org and sign in. Your firm gets its own certificate authority the first time. Every seal you issue chains to it.

  2. 2

    Upload the executed PDF

    Drop in the signed agreement. Let's Seal seals the whole file with your firm's certificate as a PAdES signature covering every byte.

  3. 3

    It's anchored for you

    The file's fingerprint is timestamped on the blockchain and written to the public transparency log. You get back a normal PDF that also verifies.

  4. 4

    Share the proof link

    Every sealed document has a permanent proof page. Put the link in the closing bundle; anyone opens it to confirm the document is authentic and unchanged.

Step by step · the CLI

Automate it from your terminal or CI

The sealbot CLI does the same thing, scriptably, one command per file, straight into your pipeline.

# Seal an executed agreement under your firm's certificate
$ sealbot seal settlement-agreement.pdf --org examples
sealed   settlement-agreement.pdf
  sha256 9f2c4e…a41b
  proof  https://letsseal.org/d/9f2c4e…a41b
  anchored to the blockchain · recorded in the transparency log

# Anyone confirms it, public, free, offline-capable
$ sealbot verify settlement-agreement.pdf
✓ authentic · unaltered · sealed by Let's Seal Examples

Sealing uses your firm's key, an API key or your own instance. Verifying is public: opposing counsel or a court runs it against the portal, or offline with a standard PAdES validator.

Full CLI & API reference
See it in action

What a proof looks like, and what you can seal

Issuer verified, controls letsseal.org
Authentic & unaltered
Document
A sealed settlement agreement
Issuer
Let’s Seal Examplesletsseal.org
SHA-256
64-hex fingerprint ✓

Anchored on the blockchain

Recorded in the public transparency log

Public and free to verify, by anyone, with standard tools.
Open the live proof

A single use case, many documents. Each of these is sealed the same way:

  • A sealed settlement agreement

    Live proof

    Open the proof page the way opposing counsel would: it shows the document is authentic, unaltered since sealing, sealed by the issuing firm, and timestamped on the blockchain.

  • An executed contract or deed

    The same holds for any executed agreement, a share purchase, a lease, a loan agreement: seal the signed PDF and the exact executed version is the one that verifies. A changed clause or amount is caught instantly.

  • A legal opinion or engagement letter

    Advice and engagement terms sealed under the firm's certificate, so a client or regulator can confirm the document they hold is the one the firm actually issued.

  • A disclosure bundle in litigation

    Seal each item as it's collected and the bundle is provably unchanged from disclosure onward, a clean chain of custody an opponent can't dispute.

Live proofs are real documents sealed under the “Let’s Seal Examples” organisation.

Common documents

What you’ll seal

  • Contracts & deeds
  • Legal opinions
  • Engagement letters
  • Wills
  • Affidavits
  • Powers of attorney
  • Court filings
  • Disclosure bundles
  • Settlement agreements
Questions

Straight answers

Does this replace a wet signature or a notary?
No. A seal proves the document is authentic, unaltered, sealed by your firm, and existed by a date, integrity, issuer, and time. It doesn't witness a person's identity the way a notary does. It's the cryptographic layer beneath whatever signing or witnessing your matter requires.
Can the other side verify without an account?
Yes. Verification is public and free. Opposing counsel or a court opens the proof link, or runs the standard tools offline. The proof carries everything they need.
What happens if the document is amended later?
Seal the amended version too. Each version gets its own seal and timestamp, so the record shows exactly what existed when, useful when a dispute turns on which draft was in force.
Is it standards-based and durable?
The seal is a standard PAdES/X.509 signature and an OpenTimestamps blockchain anchor, the same primitives courts and auditors already recognise, delivered inside the PDF and verifiable for years.

Start sealing law & legal documents

Free and open. Seal in the app, automate from the CLI, and hand anyone a proof they can verify themselves.

Open the app All use cases