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blockchain timestamps · ethereum l2

Certification with a
timestamp

Your document’s SHA-256 fingerprint, anchored on Arbitrum One — Ethereum’s L2 with security inherited from mainnet. Today you get cryptographic, immutable proof of existence. In Q4 2027 we add the eIDAS seal that turns it into legally admissible proof across the EU.

certify a document → see roadmap
arbitrum one · l2 ethereum sha-256 eIDAS Q4 2027
~/stamps · cert.log live
  1. 01

    DOCUMENT

    Contrato NDA.pdf

    2.4 MB · PDF/A-3

  2. 02

    SHA-256 HASH

    Unique, immutable fingerprint

    a7f3b2e4c8d1f9…3c8a1e9b

  3. 03

    BLOCK

    Anchored on Arbitrum One

    #385204917 · finality on L1

  4. 04

    eIDAS SEAL

    Coming in Q4 2027

    Qualified timestamp · EU-accredited QTSP

Network
Arbitrum One
Algorithm
SHA-256
Legal validity
Q4 2027

Planned

Confirmation
<1 s

chapter 01 process

Three steps. No middlemen.

We never hold your documents — only their cryptographic fingerprint.

  1. I your call

    upload.

    You pick the file. The SHA-256 hash is computed locally, in your browser; the document never leaves your device.

  2. II <1 sec

    anchor.

    The hash is written into an Arbitrum One transaction, with finality inherited from Ethereum L1.

  3. III instant

    certify.

    You get a PDF certificate with a public-verification QR code and the transaction reference.

chapter 02 roadmap

From testnet to full legal validity.

A record on-chain proves existence and integrity today. The eIDAS seal adds legal presumption on top of that — it does not create the proof.

  1. Completed Feb 2026

    Previous phase · Sepolia testnet

    Testnet validation

    Smart contract deployed on Sepolia in February 2026 and validated with real certifications before moving to production. Certificates issued then still verify today, against a contract we no longer write to.

    0xbFe489EC5e37F07d3799Bc31594E76f39A9F1660
  2. In production Jul 2026

    Live · Arbitrum One

    Production on Arbitrum One

    Source code published and verified. Every certificate generates a real transaction on Arbitrum One — Ethereum’s L2, with security inherited from mainnet and finality on L1.

    0x3FeB20A9e16BC045DAEd673AF0feD62C948231BF
  3. Q4 2027 Q4 2027

    Accredited EU QTSP integration

    eIDAS seal

    Integration with a qualified Trust Service Provider from the EU Trusted List. Timestamp compliant with Regulation UE 910/2014, with probative value across the 27 member states.

check it yourself

Everything above is on a public chain. Open a real certificate and read it straight off Arbiscan — no account, no cost.

open a real certificate

Phase 3 · Q4 2027

Not just blockchain. EU legal validity too.

A blockchain record proves that something existed at a given moment, but a judge normally needs expert technical testimony to accept it as evidence.

In Q4 2027 we integrate Komma Stamps with a qualified Trust Service Provider from the EU Trusted List. The two layers stack: the chain is what proves it, and the seal is what saves you from having to explain it.

  1. layer 1 active

    On-chain record

    proves
    Existence and integrity
    in court
    You carry the burden: it takes expert technical testimony
  2. layer 2 Q4 2027

    Qualified QTSP seal

    proves
    Legal presumption (Art. 41 eIDAS)
    in court
    The burden flips: the other side has to rebut it
  • Admissible as evidence in all 27 EU member states
  • Seal compliant with the ETSI EN 319 421 standard
  • The seal is added on top: your record on-chain does not change
Arbitrum One L2
Ethereum L1

k ;

Komma Stamps

Certificate of authenticity

Preview · Q4 2027 format

Document
Contrato NDA.pdf
Issued
Q4 2027 · UTC
Network
Arbitrum One · L2

SHA-256

a7f3b2e4c8d1f94a5c3b7d4e2f9a53c8a1e9b7c5d3a2f1e4b0c6d8e2f4a6b8c0

eIDAS · Q4 2027 ETSI EN 319 421

chapter 03 features

Technical layer today, legal on the way.

Total immutability

Permanent record on Arbitrum One. Impossible to modify, delete or forge. Cryptographic finality inherited from Ethereum L1 before the final certificate is issued.

UTC timestamp

Date and time recorded in the block. A temporal reference that is cryptographically verifiable, and neither forgeable nor retroactive.

Q4 2027

eIDAS seal

Qualified timestamp issued by an EU-accredited QTSP. Legal presumption of authenticity, admissible across the 27 member states.

Q2 2026

REST API

Programmatic integration for teams with volume. Endpoints, limits and terms will be published before launch.

Verifiable QR

Every PDF carries a QR code that opens public verification. Anyone who receives the document can check it — no account, no cost.

chapter 04 verification

Two ways to check. One is free forever.

Whoever receives your certificate should never hit a paywall to trust it.

No account

The certificate QR

stamps.kommasofthouse.com/v/{uuid}

Anyone who receives your document scans it and sees the hash, network, block, date and the link to Arbiscan. Free, no sign-up, forever. It is the URL printed on your certificates.

open a real certificate
Account + plan

The verification tool

stamps.kommasofthouse.com/verify

Paste any hash, upload a file to compute it locally, or verify in batch. Each check is a real read against the chain — that is what your plan covers.

open the tool

chapter 05 plans

Certify from €19.90 a month.

A monthly allowance, not pay-per-use. Public verification is always included, and Arbitrum One gas fees are in the price.

free trial

One real certification, with its PDF and its QR. No card.

certify one free

5 certifications solo

solo

€19.90 / month

€3.98 / certification

Freelance work and protecting creative output.

  • 5 certifications / month
  • PDF certificate with QR
  • Public verification included
Start with Solo
Most popular

pro

€79.90 / month

€2.66 / certification

Small practices certifying on a regular basis.

  • 30 certifications / month
  • Verification tool with no monthly cap
  • Priority support
Get Pro

studio

€179.90 / month

€1.80 / certification

Teams with volume and programmatic integration.

  • 100 certifications / month
  • Batch verification
  • Priority support
Get Studio
Custom

enterprise

Custom

Your own smart contract, your own brand.

  • Unlimited certifications
  • Your own smart contract
  • Full white-label: certificate, verification and panel
  • 99.9 % SLA
  • Dedicated account manager
Talk to sales
// top-up: €4.90 / certification // pack of 10 for €44.90 // prices exclude VAT · gas fees included

chapter 06 questions

What everyone asks.

¿Un certificado blockchain tiene validez legal real hoy?

Por sí solo, un registro en blockchain prueba existencia e integridad, pero normalmente requiere peritaje técnico para ser aceptado en juicio. A partir de Q4 2027, con la integración eIDAS, cada certificado incluirá sello de tiempo cualificado emitido por un QTSP acreditado UE, con presunción legal según el Reglamento UE 910/2014. Mientras tanto, los certificados actuales sirven como prueba técnica de existencia.

¿Por qué Arbitrum One y no Ethereum mainnet?

Arbitrum One es la L2 de Ethereum más adoptada: hereda la seguridad de mainnet (los datos finalizan en Ethereum L1 vía rollup) con costes unas 100× menores y confirmaciones sub-segundo. Eso nos permite certificar a un precio sostenible sin renunciar a la inmutabilidad criptográfica. Para la validez eIDAS la red es secundaria: lo que importa es el sello cualificado del QTSP.

¿Qué se guarda exactamente en la blockchain?

Solo el hash SHA-256 del documento — una cadena de 64 caracteres. Nunca el contenido. El documento original se queda contigo. Nunca llega a nuestros servidores: el hash se calcula en tu navegador.

¿Puede alguien verificar mi certificado sin cuenta?

Sí. El QR de cada certificado abre una página pública que muestra el hash, la red, el bloque y la fecha, con enlace a Arbiscan: sin cuenta, sin coste, para siempre. Lo que sí requiere cuenta con plan activo es la herramienta de verificación: pegar cualquier hash, subir un archivo o verificar en lote.

¿El gas fee se cobra aparte?

No. Los gas fees de Arbitrum One están íntegramente incluidos en el precio del plan. Pagas lo que ves: sin sorpresas ni cargos variables por congestión. Es posible porque Arbitrum mantiene costes muy bajos y estables, algo inviable en Ethereum mainnet, donde el gas se trasladaría al cliente.

¿Qué pasa si no uso mis certificaciones del mes?

La bolsa se renueva cada ciclo y no acumula. Si un mes necesitas más, puedes añadir recargas sin cambiar de plan.

¿Tendrá API REST?

Sí, está planeada para Q2 2027. Cuando lance publicaremos documentación completa, endpoints, SDKs y condiciones de uso. Si necesitas integración programática antes de esa fecha, contacta con nosotros para discutir opciones Enterprise.

blockchain today, eIDAS tomorrow

Start sealing what matters with today’s date.

Already in production on Arbitrum One. eIDAS seal in Q4 2027. Every step with a published date.

the block would say  

certify one free see plans