Let’s Seal

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 Bitcoin — 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
Bitcoin 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 Bitcoin ledger — 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 Bitcoin

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