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Powerful eSignature API built for developers

Easily embed end-to-end eSignature workflows into your apps. Trusted by millions, our 25+ years of API expertise ensures an excellent user experience.

Postman Developer's Choice Award 2025 badge

Postman Developer Choice Award - 2025

Recognized by developers worldwide for ease of integration.

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Trusted by 50,000+ businesses worldwide

BoldSign rated 4.7 out of 5 stars on G2BoldSign top-rated eSignature application on GetApp
Fast and reliable

Start sending contracts in minutes

Deliver seamless eSignature experiences with just a few lines of code.

# Replace with the template ID from your BoldSign web application.
curl -X 'POST' \
'https://api.boldsign.com/v1/template/send?templateId={your_template_id}' \

-H 'accept: application/json' \
-H 'X-API-KEY: {your_api_key}' \
-H 'Content-Type: application/json' \

-d '{
  "roles": [
    {
      "roleIndex": 1,
      "signerName": "David",
      "signerEmail": "david@cubeflakes.com"
    }
  ]
}'
Key stats

Why BoldSign?

Years in business
25+
Countries
120+
Customers
50,000+
Uptime reliability
99.999%
Key features

Powerful features, designed for developers

API dashboard

Developer-friendly dashboard and tools

Track and manage your eSignature processes using our centralized API dashboard with real-time insights, detailed reports, and a dedicated sandbox environment.

  • Real-Time Insights

    Monitor API usage and performance metrics in real time

  • Detailed Reports

    Gain full visibility into document tracking and API activity logs.

  • Sandbox Environment

    Test and refine your integration before going live.

SDKs

BoldSign SDKs: A developer’s best friend

BoldSign provides SDKs for leading frameworks, ensuring effortless integration into your existing tech stack — no matter what it looks like.

Explore SDKs BoldSign SDKs for .NET, Python, Java, Node.js and PHP
Security and Compliance

Legally Valid.
Fully Secure.
Always Compliant.

BoldSign meets top global standards like SOC 2, GDPR, HIPAA, and PCI DSS. Every signature is legally enforceable under the ESIGN Act, eIDAS, and global laws. With AES-256 encryption, your data stays protected from start to finish.

View security policy
Security and Compliance
Scalability

Built for scale and performance

Whether you’re sending 10 or a million documents, BoldSign is engineered to scale with your business. Experience lightning-fast signing speeds and reliable API responses, even with heavy traffic.

Transparent pricing

One plan. Pay only for what you use.

View pricing page

Enterprise

Starts at $30/mo, includes 40 envelopes

$0.75/ per envelope

  • Customized branding
  • Embedded requesting
  • Embedded signing
  • Embedded templates
  • Embedded custom field
  • Unlimited templates
  • ID verification

Prices shown are in USD. Final charges may vary based on currency conversion and applicable taxes.

Reviews

Don't take our word for it.

  • BoldSign G2 eSignature Leader Summer 2026 badge
  • BoldSign G2 eSignature Leader Mid-Market Summer 2026 badge
  • BoldSign G2 eSignature Leader Small Business Summer 2026 badge
  • BoldSign G2 eSignature Momentum Leader Summer 2026 badge
Read our reviews

Check out our reviews on G2 to see what customers have to say about BoldSign.

  • Exactly what I needed for API-based proposals

    I needed a way to send and manage proposals programmatically through my web app without manual steps in between. BoldSign's API made that possible and the implementation was straightforward enough that I could get it working quickly without a lot of headaches.

    G2 Logo

    Michael P.

    Posted on May 8, 2026

  • Seamless Signatures with BoldSign, Highly Recommended

    BoldSign solves not receiving necessary signatures in a timely manner, especially for customers without a printer or scanner. It provides a seamless way to collect signatures and perform work.

    G2 Logo

    Ashly T.

    Posted on May 13, 2026

  • Seamless Transition and Stellar Support with BoldSign

    BoldSign offers affordable e-signatures with an unlimited signature pricing plan and excellent customer support, providing full feature parity without a premium price tag. It's proactive in support and cost-effective compared to our previous use of DocuSign.

    G2 Logo

    Robert B.

    Posted on May 27, 2026

Best in-class documentation

Quick Start: Integrate BoldSign APIs Effortlessly

  • Interactive Use Case Demo

    Experience how BoldSign fits into real-world scenarios with our interactive demos. Explore key workflows and see the API in action.

    Try now: Interactive Use Case Demo
  • Postman Collection

    Quickly test and explore our API with the preconfigured Postman collection. Save time with ready-to-use API calls and examples.

    Download now: Postman Collection
  • API Reference

    Access comprehensive API documentation with detailed endpoints and request/response examples for seamless integration.

    View documentation: API Reference
  • API Explorer

    Interact with the BoldSign API in your browser. Test requests, view responses, and get instant feedback in real time.

    Explore now: API Explorer
  • SDKs

    Simplify integration with our SDKs for popular programming languages like .NET, Python, Node.js, and more.

    View SDKs: SDKs

Frequently Asked Questions

What is an eSignature API?
What functionalities can be performed with the BoldSign API?
How much does the eSignature API cost?
Can I send signature requests on behalf of another user?
Can I test the API for free?
Is BoldSign’s REST API secure?
Does BoldSign support bulk sending via API?

Sign up for your free trial today!

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  • YesNo credit card required
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