LetsSeal

Seal and verify certificates of conformity & trade documents

Certificates of conformity, mill certificates, test reports, and bills of lading that carry their own proof, so a customer, a customs officer, or an auditor can confirm a document is genuine, and forged conformity certs and altered test reports fail on sight.

For manufacturers, logistics, food & agri, and automotive.

Open the app Developer docs
What a seal proves

Four guarantees, in manufacturing & trade

Certificates that can't be forged

A changed grade, result, or spec fails verification. The fake-conformity-cert and doctored-mill-cert problem, a real one in steel, materials, and food, closed at the source.

The manufacturer or lab, named

Every certificate and report names the organisation that sealed it, chaining to a published root, provable issuer, not a copied stamp.

Fixed at the moment of issue

The issue date is timestamped on the blockchain, decisive for batch traceability, recalls, and which certificate applied to which lot.

Verified across the supply chain, free

A customer, a customs officer, or an auditor confirms a document at a permalink, instantly, and free, anywhere along the chain.

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 document or file
Seal
Signed over every byte · PAdES / detached CMS
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 organisation

    Open app.letsseal.org and sign in. Your organisation gets its own certificate authority for sealing certificates and reports.

  2. 2

    Seal the certificate or report

    Upload the CoC, mill cert, or test report; it's sealed over the whole file, so any later edit to a grade or result is caught.

  3. 3

    Or anchor raw test data by hash

    For large datasets and instrument output, anchor just the hash. The data never leaves your systems, only the digest.

  4. 4

    Ship with a proof link

    Every document has a permanent proof page. Put the link with the goods or the shipping pack; anyone downstream verifies it's genuine.

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 every certificate of conformity as it's issued
$ sealbot watch /srv/certs --mode seal --org examples
watching /srv/certs … sealing new & changed PDFs (idempotent)

# Seal a mill certificate under your organisation
$ sealbot seal mill-certificate-3.1.pdf --org examples
sealed   mill-certificate-3.1.pdf
  proof  https://letsseal.org/d/9c04af…5d31

# A customer or customs officer confirms it, public, no account
$ sealbot verify mill-certificate-3.1.pdf
✓ authentic · unaltered · sealed by Let's Seal Examples

Seal certificates and reports as they're issued, or anchor raw test data by hash. Each carries a permanent proof link verifiable anywhere along the supply chain, no per-seal fee.

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 certificate of conformity
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 certificate of conformity

    Live proof

    Open the proof page the way a customer's goods-in team would: it shows the certificate is authentic, unaltered, issued by the named manufacturer, and timestamped. A forged CoC can't pass.

  • A mill or material certificate

    Seal EN 10204 3.1 mill certs so a fabricator or inspector can confirm the material grade and heat data are exactly as certified, a known target for forgery.

  • A test or inspection report

    Lab and QC reports sealed on issue, so a customer or auditor can verify the results are the genuine, unedited findings.

  • A bill of lading or customs document

    Trade and shipping documents sealed and dated, so a customs officer or consignee can confirm they're genuine and unaltered in transit.

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

Common documents

What you’ll seal

  • Certificates of conformity (CoC)
  • Mill / material certificates
  • Test & inspection reports
  • Bills of lading
  • Customs documents
  • Batch / lot records
Questions

Straight answers

Does this stop fake conformity or mill certificates?
A sealed certificate can't be edited without failing verification, and anyone downstream can check it against the proof link. A forged CoC or doctored mill cert, a real problem in materials and food supply chains, simply won't verify as issued by you.
How does a customer verify a certificate?
They open the proof link, or drop the PDF into the public verifier. It confirms the certificate is genuine, unaltered, and issued by the named manufacturer or lab, with no call required.
Can I seal certificates at production volume?
Yes. Point the CLI or a watched folder at your QA output and every certificate leaves sealed, timestamped, and carrying a proof link, one command per file, no per-seal fee.
What about large raw test datasets?
Anchor just the SHA-256, the data never leaves your systems, only its digest, and still prove it existed unaltered as of a date.

Start sealing manufacturing & trade 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