2025 AssureSign API Review + The Best Alternative

Quick Summary

This guide reviews the AssureSign API in 2025, highlighting its features, pricing, and limitations since becoming part of Nintex. We explain why it fits enterprises more than smaller teams and compare it with SignWell, a flexible, cost-effective alternative. If you’re researching e-signature APIs, use this review as a starting point, then explore more insights on our blog.

Wondering if the AssureSign API is any good?

The AssureSign API offers a comprehensive platform for automating document signing. We’ve seen firsthand how it streamlines workflows, saving time and reducing manual tasks.

However, its pricing isn’t transparent, and since Nintex acquired and integrated it into its broader process automation platform, it has become quite inaccessible to non-enterprise grade users.

In this SignWell article, we review the AssureSign API, looking at its key features, limitations, and pricing. Then we compare it with Signwell, a better alternative.

Why Listen to Us?

We at SignWell have helped over 65,000 businesses streamline their document workflows, with more than 10 million documents signed securely on our platform. Our focus is on making e-signatures simple, affordable, and legally compliant for companies of all sizes. With years of experience building trusted solutions, we provide the tools and guidance businesses need to simplify signing and improve efficiency.

What Is Assuresign API?

The AssureSign API, now Nintex eSign, is a flexible e-signature platform that allows businesses to automate document signing workflows. It integrates seamlessly with existing applications, providing a customizable solution for collecting legally binding signatures across industries.

Its ability to handle multi-step workflows and ensure compliance with e-signature laws makes it ideal for organizations needing secure, streamlined document processing. AssureSign also supports SMS and in-person signing for added convenience.

Key Features of AssureSign API

• Multi-Party Signing: Facilitates the signing of documents by multiple recipients in a specified order, ensuring a structured and efficient signing process.
• Customizable Templates: Allows users to create and manage reusable templates, reducing the time spent preparing documents for signing.
• Audit Trails: Provides detailed logs of all actions taken on a document, enhancing transparency and accountability.
• In-Person Signing: Enables documents to be signed in person, accommodating scenarios where remote signing is not feasible.
• SMS Notifications: Sends text message alerts to signers, improving engagement and reducing turnaround times.
• API Integration: Offers RESTful API endpoints for seamless integration with existing systems, automating the document signing process.
• Signer Authentication: Implements various authentication methods to verify the identity of signers, ensuring the security and legitimacy of signed documents.
• Real-Time Tracking: Provides real-time updates on the status of documents, allowing users to monitor progress and take timely actions.
• Document Storage: Stores signed documents securely, making them easily accessible for future reference or compliance purposes.
• Compliance Management: Ensures that all signed documents comply with relevant legal and regulatory requirements, mitigating potential risks.

Pricing

AssureSign API (now Nintex eSign) does not publish public pricing. Businesses must request a quote directly. Pricing is typically tiered by document volume and edition, with some public-sector schedules showing annual costs ranging from several thousand to tens of thousands, depending on usage.

Estimates suggest annual pricing ranges from $25,000–$50,000, making it cost-prohibitive for small to midsize businesses.

What We Like

• User-Friendly Interface: The platform’s dashboard is clean and straightforward, allowing teams to begin using it with minimal training or technical setup requirements.
• Efficient Document Management: Documents can be quickly accessed, organized, and tracked, allowing teams to instantly locate documents through an indexed search.
• Seamless Integration: Works smoothly with leading CRMs and cloud storage providers, making it easier to connect e-signatures directly into existing tools without disrupting established processes.
• Strong Security Features: Protects sensitive documents through SSL encryption and compliance with major regulations, giving businesses confidence that their digital agreements remain secure and legally valid.

What We Don’t Like

• Limited Template Management: The template tools can feel restrictive, with some users noting difficulty customizing and reusing documents compared to more flexible alternatives.
• Opaque Pricing: The absence of publicly available pricing forces every prospect to go through sales, making it difficult to budget, compare options, or evaluate affordability upfront.
• Small Business Accessibility: Designed primarily for larger organizations, the platform’s structure and pricing make it less practical or approachable for startups and smaller teams.
• Support Response Times: Customer support is helpful but not always timely, with some users reporting slower email replies that can delay resolution of technical issues.
• High Pricing for SMBs: Without transparent pricing, many businesses often discover costs are significantly higher than expected, creating barriers for teams that need predictable, flexible expenses.

SignWell API: A Better Alternative to AssureSign API

SignWell API addresses key limitations of traditional e-signature platforms, particularly in terms of ease of use and integration flexibility. It offers a straightforward setup and efficient document management, making it accessible for businesses of all sizes.

Unlike AssureSign, SignWell provides a more user-friendly template management system, streamlining workflows without complexity. It emphasizes ease of setup and flexible authentication methods, meeting the needs of industries that require secure, legally compliant signatures.

Additionally, SignWell’s responsive customer support ensures timely assistance, and its pricing structure caters to both small businesses and larger enterprises, offering a cost-effective solution without compromising essential features.

Key Features

SignWell’s e-signature API offers a range of features designed to integrate digital signing capabilities into applications and websites efficiently.

• Embedded Signing: Integrates e-signature functionality directly into websites or applications, letting users sign documents within your platform for a seamless, uninterrupted experience.
• Automated Workflows: Simplifies document preparation and sending, automating reminders and notifications so agreements move forward efficiently without manual intervention from your team.
• Reusable Templates: Supports creating customizable document templates with predefined fields, reducing repetitive tasks and ensuring consistent, error-free document preparation across different teams and departments.
• Audit Trails: Generates complete logs of every action on a document, who signed, when, where, and on what device, ensuring accountability, compliance, and transparency.
• Secure & Compliant E-Signatures: Delivers legally binding signatures that meet U.S. and international standards, including ESIGN, UETA, and GDPR, guaranteeing documents remain valid and secure worldwide.
• White Labeling: Let’s organizations customize the signing interface with logos, colors, and branding elements, creating a unified and professional user experience for signers.
• Real-Time Document Tracking: Provides live updates on document status, alerting you the moment documents are opened, signed, or finalized, so teams stay informed and responsive.
• Flexible Pricing: Offers cost-effective pay-as-you-go pricing, charging only for used signature requests, with the first 25 API documents every month completely free.
• Developer Support: Includes dedicated developer assistance, with extensive API documentation, sample code, and integration guides that make implementation faster and less complex.
• High Availability: Guarantees reliability, ensuring document signing operations remain uninterrupted and always available for businesses that require continuous workflow stability.

Pricing

SignWell offers a flexible, pay-as-you-go API pricing model:

• API Plan: $0.75 per document. The first 25 API documents each month are free. Billing occurs monthly, based on usage. No contracts are required. A 10% discount is available for annual payments.

This pricing structure is designed to scale with your usage, making it cost-effective for businesses of all sizes.

For developers, a free account provides unlimited API test usage and up to 3 documents per month. This allows for thorough testing and integration without immediate costs.

Enterprise plans are available for high-volume users, offering customized solutions to meet specific needs. Pricing for these plans is tailored based on usage and requirements.

Overall, SignWell’s API pricing is designed to be flexible and scalable, accommodating businesses of various sizes and usage patterns.

AssureSign API vs SignWell API: Side-by-Side Comparison

Why Choose SignWell API Over AssureSign API?

Here are five reasons why businesses choose SignWell over AssureSign API:

• Developer-Friendly API with Clear Documentation

SignWell’s API is designed with developers in mind, offering a straightforward RESTful interface that simplifies integration into web applications. The platform provides comprehensive, up-to-date documentation, including code examples and SDKs in multiple programming languages. This clarity reduces the learning curve and accelerates development timelines. In contrast, AssureSign’s documentation is less detailed, potentially requiring more time for developers to understand and implement the API effectively.

• Transparent and Scalable Pricing Model

SignWell employs a pay-as-you-go pricing structure, charging $0.75 per document with the first 25 API documents free each month. This model is advantageous for businesses with fluctuating signing volumes, as it avoids the commitment of fixed monthly plans. AssureSign, on the other hand, offers annual plans starting at $2,000, which may be less flexible for smaller businesses or those with variable needs.

• Embedded Signing Capabilities

SignWell allows developers to embed the signing experience directly into their applications, providing a seamless user interface without redirecting users to external platforms. This feature enhances user experience by maintaining brand consistency and reducing friction in the signing process. AssureSign’s embedded signing options are more limited, potentially leading to a less cohesive user experience.

• Comprehensive Compliance and Security

SignWell ensures compliance with major e-signature laws, including the ESIGN Act, UETA, and eIDAS, and offers features like audit trails and end-to-end encryption. These measures provide standard security and legal validity for signed documents. While AssureSign also complies with relevant regulations, SignWell’s transparent approach to security and compliance provides verified audit trails that confirm document integrity.

• Responsive Developer Support

SignWell provides dedicated developer support, offering assistance through various channels to help with integration and troubleshooting. This support is crucial for developers seeking timely resolutions to issues. AssureSign’s support options are more limited, which could result in longer response times and potentially hinder development progress.

Key Takeaway 

AssureSign (Nintex eSign) is best suited for enterprise-scale workflows that need deep integration into the Nintex automation ecosystem, but its pricing opacity and more complex setup can be barriers for smaller teams. 

SignWell, on the other hand, offers an intuitive API, transparent pay-as-you-go pricing, and broad compliance, making it an attractive choice for businesses of all sizes, especially those that value simplicity, affordability, and fast integration.

Make the Smart Choice for Your E-Signature Needs

In this article, we reviewed the AssureSign API  and compared it with our top e-signature solution, highlighting key features, pricing, and integration options. Businesses looking for a flexible, seamless API choose SignWell.

SignWell offers a powerful, cost-effective e-signature API with exclusive features like real-time tracking, customizable templates, and secure document management. With transparent pricing and excellent support, it’s a great fit for both small businesses and large enterprises.

Start your free trial of SignWell today and simplify your document workflows.