Frequently Asked Questions

We have 2 types of signatures available.

Simple Electronic Signature (SES)
Perfect for most common needs, easy and fast. With OTP (one-time password) via email or SMS.
Compliant digital preservation optionally available.

Advanced Electronic Signature (AES)
Ideal for special cases requiring higher evidentiary value. Requires identification of the signer. Mandates compliant digital preservation of the proof file and insurance coverage.

Certainly, if you have high volumes and your application generates documents to be signed, the ideal solution is to connect your software with ours to automate the entire signing process.

Everything will be automatic, and the result will be that your management system will receive the signed documents back or even have them already stored in compliant digital preservation without any manual intervention.
You can read the technical documentation at the following link: https://www.otpservice.io/it/api/

No additional costs.

No! We are the only ones offering the service without subscription commitments or automatic renewals. With OTP SERVICE, you pay as you go: costs are deducted from a prepaid credit that lasts for 3 years and whose expiration is renewed with each recharge.

Yes, you have 3 completely free signatures available monthly. The free plan excludes APIs and OTPs sent via SMS.

In short, the simple electronic signature (SES) is a very easy-to-use remote signing method that is legally recognized in Italy and Europe. The degree of its legal value is determined by a judge in case of dispute.

We at OTP service, to offer the strongest possible evidentiary value, have enhanced its features making it very similar, from the requirements point of view, to the advanced electronic signature (AES).

Every step of the signing process is recorded in an event log where every digital trace is documented. Moreover, to complete the signature, the signer is required to authenticate via an OTP sent to the email address or mobile number of the signer. For security reasons, these two data are set by the proposer and cannot be modified by the signer.

The signing process is very similar for both solutions, and the only difference compared to SES is the recognition of signers, which is only required for AES. In fact, there is specific legislation for this, and it is mandatory to carry out the recognition of the person who needs to sign.

You perform the signer’s recognition, and it can be done remotely or in person. If you do it in person, you just need to enter the signer’s data. However, if you can’t meet them physically, you can choose remote recognition and let them show their identity through our simple procedure. You’ll only need to check their ID document data and the photographic proof that will be requested. The shots will be taken in real-time, but your check is deferred. The process is indeed frozen, resumed, and concluded based on the time needed for each signer.

If the data is confirmed, the document is considered signed, and a copy is sent to each signer, with the signature certificate generated by OTP service attached to the document itself.

These are the simple steps, common to both types of signatures, to have a document signed:

1. Choose the type of signature (simple or advanced)
2. Upload the file of the document to be signed
3. Enter the data of the person or people required to sign
4. Insert the signature points in the document

These are the steps for the signer(s) who will receive the request:

1. The signer receives the link via email to start the signature process with the document to be signed already attached.
2. For the advanced signature, there’s an additional verification part
3. The signer accepts the signature points you’ve inserted by simply checking each one.
4. After accepting them all, they confirm their intent via OTP: a code valid only for a few minutes and sent to the contact, email or SMS, defined by you.
5. Done! They will receive the signed PDF and a code to check the process details

No, there’s no extra cost to encourage sharing the platform in the company with all colleagues. In fact, everyone can have their own access credentials to ensure transparency and tracking of who works on each document.

Moreover, there are no usage limitations based on a specific user. This way, there can be very active users and rare users, but they all draw from a single credit management.

To verify the validity of the digitally signed document, it is recommended to “use the online validation tool provided by the European Commission: DSS Validation Tool. Simply upload the signed file and press the ‘Submit’ button.” The validation result should show the phrase “Total passed”.

OTP Service uses HARICA (Hellenic Academic and Research Institutions Certification Authority), a Qualified Trust Service Provider (QTSP) recognized under the eIDAS Regulation and accredited by the European Commission.

HARICA participates in all major global trust programs of Certification Authorities (“ROOT CA”) — including Adobe, Apple, Microsoft, Mozilla, Oracle, and 360 — and operates as a Trust Anchor within major operating systems and software applications (Adobe, Apple, Google, Microsoft, Mozilla, Linux, Oracle Java).

This ensures the reliability and full cross-border interoperability of electronic seals affixed to documents.

You can write an email to support@otpservice.io, or book a no-obligation demo.