Customize an SMS
authentication message via the API

Ensure only verified users can access your embedded signing sessions. Enable two-factor authentication via SMS and customize the message you use to share a password with your recipient.

  • Free to test
  • Fast to deploy
  • Powerful & secure

Set up SMS authentication using the API

The signNow API makes it easy to enhance the security of your documents by preventing unauthorized users from gaining access. When configuring your embedded eSignature invite, simply add an authentication parameter to the request body and specify the authentication method – SMS, create a password, and personalize your SMS message.

  • signNow provides developers with complete SDKs for every popular language, allowing them to integrate eSignatures without writing a single line of code.
  • With signNow’s detailed documentation, integrating electronic signatures with your app is a breeze.
  • signNow goes beyond eSignatures. Use it to create fillable forms, request payments, and manage your documents securely using simple API calls.

Choose a signer authentication method that fits into your workflow

SMS verification

Send an SMS with a personalized message and unique password. Signers will be required to enter the password you shared with them via SMS to access the signing session inside your application.

Phone call verification

Provide a relevant phone number and your signer will receive a phone call prior to gaining access to an embedded signing session. The signer passes authentication once they pick up the phone call.

Password protection

Create a secret password for accessing an embedded signing session and share it discreetly with your signers. They will have to enter the password to complete the verification and access your document.

Enhance the security of your integrated signing experiences with two-factor authentication

Improved security & compliance

Confirm the identity of users before they can sign documents within your application. Reduce the risk of fraudulent activities and ensure your app complies with the highest data security regulations.

Personalized user experience

Customize the two-factor authentication process with personalized messages using the signNow API. This not only adds an extra layer of security but also enhances the user experience by making the process more engaging and intuitive.

Easy and quick implementation

All you need to set up dual-factor authentication via the API is to add a few lines of code while configuring your embedded eSignature invite.

signNow regularly wins awards for ease of use and setup

Read our reviews on the trusted resources

Tech Data uses signNow to improve our internal and external customer service while increasing our speed to revenue.
Bob Dutkowsky CEO
Bob Dutkowsky | CEO

Select an API package for your business

Integrate eSignatures into your software and get 250 legally-binding signature invites with your API free trial.

Check API pricing

Solution engineers

We are here to help you configure eSignature API to your workflow.

Review signNow’s API documentation

The detailed API tutorial will guide you through the entire integration process and provide clear coding examples.

Video guides

Watch our video guides for instructions on how to easily build custom integrations.

Start with any of our SDKs

Get complete SDKs for Node.js, Python,
PHP, Java, C#.

Enterprise-grade security and compliance

signNow is committed to protecting your sensitive information by complying with global industry-specific security standards.

GDPR compliance
GDPR compliance
Regulates the use and holding of personal data belonging to EU residents.
SOC 2 Type II Certified
SOC 2 Type II Certified
Guarantees the security of your data & the privacy of your clients.
PCI DSS certification
PCI DSS certification
Safeguards credit/debit card data for every monetary transaction a customer makes.
21 CFR Part 11
21 CFR Part 11
FDA-backed standards for electronic documentation and electronic signatures.
HIPAA compliance
HIPAA compliance
Protects the private health information of your patients.
CCPA compliance
CCPA compliance
Enhances the protection of personal data and the privacy of California residents.

Watch the signNow API in action

Start building your eSignature integration with a quick video guide

Watch the video tutorial to kick-start your project.

Trusted eSignature solution — what our customers are saying

Explore how the signNow eSignature platform helps businesses succeed. Hear from real users and what they like most about electronic signing.

Easy to use and less expensive than competitiors
Chris A

What do you like best?

The interface is very easy to use, it is less expensive than the competition, and I don't use it every day, so it's not a service I am willing to shell out a ton on as far as a monthly fee. SignNow is fair.

Read full review
Time saving application that helps me do my work no matter where I am.
User in Individual & Family Services

What do you like best?

the fact that I can access it on my mobile phone or on my pc and that I can just upload documents from my drive or from an email.

Read full review
Great Tool For Our Small Businesses
Jessica T

What do you like best?

It is easy to use, easy to send to clients. We can upload multiple templates, made adjustments to individual documents and easily review signed and pending contracts. The contracts are clean and professional looking.

Read full review

Ready to get started?

Ready to get started?

Test the capabilities of signNow’s eSignature API first-hand. Simply create your developer account and start testing API calls in the sandbox environment.

Why choose the signNow API?:

  • Free to test and easy to deploy
  • SDKs for popular languages
  • Customizable for any workflow
  • Industry-leading security & compliance