The Developer's Guide to an eSignature API

Go Live Faster

Don't spend months on integration. Our RESTful API, comprehensive documentation, and multi-language SDKs are designed for developer productivity. Get your first document signed in a single afternoon with our free developer sandbox and clear guides.

Bank-Grade Security

Protect your data and your customers with a platform built on a foundation of security. We provide end-to-end encryption and are compliant with SOC 2 Type II, ISO 27001, HIPAA, and GDPR, giving you enterprise-grade security out of the box.

Guaranteed Uptime

Your business can't afford downtime. We offer a 100% uptime SLA for our API, ensuring your document workflows are always available when you and your customers need them. Build your application on a platform you can rely on.

Legally Binding

Every signature is backed by a detailed, court-admissible audit trail. We comply with the U.S. ESIGN Act, UETA, and other global regulations, so you can be confident that your agreements are legally enforceable.

Scales With You

Whether you process 100 documents or 1 million, our infrastructure is ready. With transparent, volume-based pricing, you get a predictable cost model that scales as your business grows, without performance degradation.

Expert Support Included

You're not alone. Our API plans include access to our team of integration specialists. Get expert help with code, workflow design, and best practices at no extra cost, ensuring your project's success.

Total Workflow Control

Don't settle for a rigid, one-size-fits-all solution. Our API offers deep customization, from fully embedded signing and dynamic templates to complex conditional logic and multi-party routing. If you can map the workflow, our API can automate it.

Seamless User Experience

Keep users inside your app with our embedded signing feature. Customize the look and feel to match your brand, eliminating the jarring experience of being sent to another website. This reduces drop-off and increases completion rates.

Instant Notifications

Use webhooks to get real-time status updates for every stage of the signing process. Trigger downstream actions in your application the moment a document is viewed, signed, or completed, creating a fully automated and responsive system.

REST API

Our API follows RESTful principles, making it predictable, easy to work with, and compatible with any modern tech stack.

JSON

We use lightweight and human-readable JSON for all API requests and responses, simplifying data handling for developers.

OAuth 2.0

We use the industry-standard OAuth 2.0 protocol for secure authentication, ensuring your API calls are properly authorized and protected.

Webhooks

Build event-driven applications with webhooks that provide real-time notifications, eliminating the need for constant polling.

SOC 2 Type II

Our SOC 2 compliance demonstrates our commitment to enterprise-grade security and data protection, a critical requirement for B2B.

HIPAA

For healthcare applications, our HIPAA compliance and willingness to sign a Business Associate Agreement (BAA) is essential.

ISO 27001

This international standard for information security management gives you confidence in our processes for protecting your data.

GDPR / eIDAS

Operating in Europe? Our compliance with GDPR and eIDAS ensures your signing process meets strict EU regulations.

Node.js

We provide a native Node.js SDK to accelerate backend integration for one of the most popular server-side environments.

Python

Our Python SDK simplifies integration for developers working with Django, Flask, or other Python-based frameworks and scripts.

PHP

Integrate seamlessly with popular PHP applications like Laravel or Symfony using our dedicated PHP SDK.

Ruby

For teams building with Ruby on Rails, our Ruby gem makes it fast and easy to add eSignature capabilities.

.NET / C#

Enterprise developers using the Microsoft stack can leverage our .NET SDK for robust integration with their C# applications.

Java

Our Java SDK supports integration with a wide range of enterprise systems and Android applications built on the Java platform.

AWS

Our infrastructure is built on AWS, providing the scalability, reliability, and global reach your application needs to perform.

Self-Service (Free & Paid Plans)

Ideal for teams with in-house developers who are comfortable with API integrations.

• Access to the full eSignature API
• Comprehensive API documentation and SDKs
• Free developer sandbox environment
• Community and email-based support

QuickStart Implementation Package

Companies that want to go live quickly but have limited developer availability.

• Initial workflow discovery workshop
• End-to-end integration for one core use case
• Configuration of templates and branding
• User acceptance testing and go-live support

Managed Services & Dedicated Support

Enterprises with complex, mission-critical workflows or those requiring ongoing development.

• A dedicated team of API experts
• Ongoing development of new workflows and features
• Proactive system monitoring and optimization
• Priority support with guaranteed response times (SLA)

API Integration Effort

Challenge: API integrations are a resource drain. We don't have the developer time.

The eSignly Advantage: Our REST API is built for speed. With our comprehensive documentation, SDKs, and a free developer sandbox, you can get your first proof-of-concept running in an afternoon, not weeks. Plus, our 'QuickStart' service can handle the integration for you.

Security & Compliance

Challenge: We handle sensitive data. How can we trust your API's security and compliance?

The eSignly Advantage: We're built for enterprise-grade security. eSignly is compliant with SOC 2 Type II, ISO 27001, HIPAA, GDPR, and 21 CFR Part 11. All data is encrypted in transit and at rest, and every action is recorded in an immutable audit trail.

Total Cost of Ownership

Challenge: Your pricing seems higher than some competitors.

The eSignly Advantage: Our pricing reflects a complete solution, not just an endpoint. It includes our 100% uptime SLA, dedicated developer support, and guaranteed compliance. Cheaper alternatives often lead to higher total costs from downtime, support delays, and security risks.

Workflow Flexibility

Challenge: Our workflows are unique. A standard API might not be flexible enough.

The eSignly Advantage: Flexibility is our core design principle. The API supports complex routing, conditional logic, embedded signing for seamless UX, and webhooks for real-time status updates. If you have a workflow, our API can automate it.

Developer Support

Challenge: What happens if we need help? Is support an extra cost?

The eSignly Advantage: Developer support is included in our API plans. You get access to our team of integration experts who can help you troubleshoot code, design workflows, and optimize your implementation at no extra charge.

Legal Enforceability

Challenge: We need to be sure this is 100% legally binding.

The eSignly Advantage: Absolutely. Signatures made through the eSignly API are compliant with the U.S. ESIGN Act, UETA, and eIDAS in Europe. Each signature is captured with a comprehensive, court-admissible audit trail that includes timestamps, IP addresses, and a chain of custody.

API Integration & Scoping Workshop

Before writing a line of code, we'll map your existing document workflows, identify automation opportunities, and define the optimal integration strategy.

• Define clear project scope and deliverables.
• Avoid costly rework and scope creep.
• Ensure stakeholder alignment from day one.

QuickStart API Implementation

Don't have the developer resources? Our expert team can handle the end-to-end integration for you. We'll get your core use case live in a matter of weeks.

• Accelerate your time-to-market.
• Free up your internal development team.
• Guarantee a best-practice implementation.

Custom Workflow & Logic Development

For businesses with complex needs, we design and build custom signing workflows. This includes conditional routing and advanced data validation.

• Automate even the most complex business processes.
• Reduce manual intervention and human error.
• Create a powerful competitive advantage.

Embedded Signing UI/UX Customization

We help you design and implement a fully seamless, white-labeled signing experience. Our team ensures the embedded workflow perfectly matches your brand.

• Deliver a superior, integrated user experience.
• Reinforce your brand identity and trust.
• Minimize signer drop-off rates.

Compliance & Security Architecture Review

If you operate in a highly regulated industry like healthcare or finance, our compliance experts will review your architecture to ensure it meets all necessary standards.

• De-risk your implementation from a compliance standpoint.
• Ensure your solution will pass security audits.
• Build with confidence in regulated markets.

API Performance & Load Testing

Preparing for a major launch? We'll help you simulate peak loads to identify and eliminate potential bottlenecks, ensuring your integration remains fast and reliable.

• Prevent performance issues before they impact users.
• Validate scalability for high-growth scenarios.
• Ensure a smooth launch and positive user experience.

Data Migration from Legacy Systems

Moving from a manual process or another provider? We provide services to migrate your existing documents, templates, and contact data into eSignly.

• Preserve historical data and document integrity.
• Minimize disruption to business operations.
• Get up and running on eSignly faster.

Dedicated Developer Support & Training

For enterprise teams, we offer dedicated support packages and hands-on training sessions to upskill your team on our API.

• Empower your team to build and maintain the solution.
• Resolve technical issues faster.
• Maximize the long-term value of your investment.

Webhook & Downstream System Integration

We help you configure webhooks and integrate with downstream systems like your CRM, ERP, or cloud storage to create a fully automated business process.

• Eliminate manual data entry after signing.
• Create a single source of truth for your data.
• Achieve true end-to-end process automation.

Template Strategy & Optimization

We analyze your most common documents and help you create a library of optimized, dynamic templates to standardize your processes.

• Drastically reduce document preparation time.
• Ensure consistency and accuracy across all agreements.
• Simplify the signing process for all parties.

Advanced Authentication & Identity Verification

For high-value transactions, we can help you integrate advanced signer identity verification methods directly into your API workflow.

• Add an extra layer of security for critical agreements.
• Reduce the risk of fraud.
• Meet stringent industry or transaction requirements.

Custom SDK or Wrapper Development

If your team works with a programming language for which we don't have a native SDK, we can work with you to develop a custom SDK or API wrapper.

• Improve developer experience and productivity.
• Ensure code consistency across your organization.
• Reduce the learning curve for new developers.

Bulk Sending & PowerForm Automation

Need to send the same document to thousands of signers? We help you automate this process using our Bulk Send API or self-service PowerForms.

• Save hundreds of hours on mass-signing events.
• Automate processes like policy updates.
• Provide a self-service option for document initiation.

API Governance & Key Management Strategy

For large organizations, we provide consulting on best practices for API governance, managing API keys, and monitoring usage across departments.

• Maintain security and control in a large-scale deployment.
• Ensure proper access controls are in place.
• Gain visibility into API usage across the enterprise.

AI-Powered Document Intelligence Integration

Leverage the future of document processing. We help you integrate AI services that analyze and extract data from completed documents.

• Unlock valuable insights from your signed contracts.
• Automate post-signature data analysis.
• Future-proof your document management strategy.

Cameron Avery

Lead Engineer, HRFlow Solutions

"The documentation is some of the best I've ever worked with. Clear, concise, with actual useful code examples. We had a proof-of-concept for our embedded offer letter signing integrated in less than a day. The support team was also incredibly responsive."

Rachel Manning

Product Director, InsurQuote

"We needed to give our customers a way to sign policy documents without leaving our mobile app. eSignly's embedded signing API was the perfect fit. Our user completion rates have improved by 30% and the experience is seamless."

Thomas Lamb

CTO, PropertyDeal CRM

"We evaluated several eSignature APIs. We chose eSignly for its reliability, transparent pricing, and robust feature set. The ability to create complex workflows with conditional logic was a huge win for us and our real estate clients."

Tanner Ashby

CFO, Summit Manufacturing Group

"The ROI was clear from month one. By automating our supply chain contracts with the eSignly API, we've reduced our contract cycle time by over 50%. The predictable, per-signature cost model makes budgeting simple and transparent."

Orlando Gilbert

Head of Platform, LegalDraft Inc.

"Security and legal enforceability were our top priorities. eSignly's comprehensive compliance (SOC 2, ISO 27001) and detailed audit trails gave our legal team the confidence they needed to approve the integration. It's a rock-solid platform."

Kaiya Bryce

Founder, Momentum Grants

"As a small organization, we don't have a huge dev team. The eSignly API was surprisingly easy to implement, and it has completely automated our grant agreement process. It saves us countless hours that we can now focus on our mission."

Intelligent Data Extraction (IDP)

Move beyond simple signing. Our upcoming AI-driven IDP layer will automatically extract key data points from completed documents—like expiration dates, payment terms, and clause types—pushing them directly into your CRM or ERP via webhooks.

Predictive Fraud Analysis

We are training our models on millions of signing events to identify behavioral anomalies in real-time. This system will flag potential tampering, identity spoofing, or irregular signing patterns before the transaction is finalized.

Autonomous Workflow Orchestration

Stop building rigid routing rules. Our engine will soon analyze historical completion data to suggest the optimal path for document routing, dynamically adjusting signers, reminders, and escalation logic to maximize your conversion rate.