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Electronic Invoicing and Digital Signature

Meet our Sign'Stash platform


Your Software as a Service solution

Digital subscription, custody, and preservation service.

With a diverse set of features that allows integration with current invoicing systems, sending electronic invoices, digital signatures and preserving digital security. 

Main Features


REST format services and OAuth2 authentication for fast and straightforward integration


Secure transfer and safekeeping of your documents and information

eIDAS compliance

Multicert´s electronic qualified seals guarantee acceptance of your qualified signature in the European region


Sign documents in various digital formats, allowing them to be used in other business workflows

User independence

Backoffice for consultation and management of the entire service 24/7


Customization of communications and recipient consultation portals

For whom?

Companies that bill for public bodies

Companies that bill to private bodies

Companies with large and small invoicing volume 

Without worries. Feel safe with Sign’Stash


Compliance with eIDAS

Qualified electronic signature for electronic invoices recognized by eIDAS.

Signature, Custody and Digital Preservation

Multicert digital signature, custody and preservation service ensures the latest legal requirements for electronic invoices (decree-law No. 28/2019).

Trust and Accreditation

Multicert – accredited by GNS and integrated into the European Trusted List

Temporal Validation

Use of timestamps for the temporal validation of electronic invoices. (+)

(+) Legal Compliance

The Timestamps issued by Multicert comply with the legislation, namely with the following regulations and decree-laws:
Regulation (UE) No. 910/2014 of the European Parliament and Council – defines the requirement for the EU Member States to be obliged to maintain a Trust List with qualified Cas.
Commission Implementing Regulation (UE) 2015/1501 – defines the format and data to be included in the trusted list.
Decree-Law No. 88/2009 – appointment in Portugal of the body responsible for maintaining, updating and making the Trust List available in Portugal.


We are available to clarify any questions! Fill in the following form and we will contact you as soon as possible.

Sign'Stash Subscription

Business to Consumer

Business to Business

Busines to Government