With their usage increasing by more than 50% since the start of the pandemic, it’s clear that eSignatures (and eSignature APIs) are here to stay. As we edge closer and closer towards a paperless world, public perception of electronic signatures has moved from “are those even legally binding?” to something used for everything from sending money to buying a home.

If you’ve been in business for long enough, you might remember the bad old days of signing documents “electronically”: receive document via email, download PDF, fail to have an app capable of editing PDFs, print document, physically sign, scan, email it back, repeat.

It’s a process that was fiddly, time-consuming, and impossible to automate or scale. But eSignature APIs have changed all that. Below, we’ll look at a few common use cases for eSign APIs before diving into some popular solutions on the market and where they can be useful.

eSignature API Use Cases

As of the year 2000, thanks to the US Federal eSign Act, an eSignature is defined as an “electronic sound, symbol, or process, attached to or logistically associated with a contract or other record and executed or adopted by a person with the intent to sign the record.” In other words, any method of marking a document electronically in a legally binding way.

eSignatures can now be used for everything from sales contracts to licensing agreements, which you’re probably already well aware of if you’ve found yourself reading this piece, and using associated APIs enables integrations with other tools and services for things like:

• CRM
• Healthcare
• Order fulfillment
• Employment contracts
• Real estate
• Age verification

In other words, anything that might once have required someone to put their John Hancock on the dotted line. eSignature APIs are helpful for automating aspects of form completion, reducing the costs associated with sending paperwork, and simplifying document storage. Only recently, however, have they begun to unlock the full potential of the terminology used in the eSign Act.

7 Top eSignature APIs

Let’s check out some popular eSignature APIs on the market and look at their specialties, relevant features, and so on, to see if we can identify any emerging trends in this space.

1. Dropbox Sign

Formerly known as HelloSign — Dropbox acquired the company and its API back in 2019 — Dropbox has invested heavily in workflow interoperability. That means, unsurprisingly, an emphasis on encouraging users to remain within the Dropbox ecosystem. If you’re already using their productivity tools or storage API, this might be an obvious choice to experiment with.

Dropbox Sign’s API is also technically an award-winner, taking home the Best in Business Software APIs prize at API World 2022, as well as being called one of the easiest to implement eSignature APIs by G2. It offers embedded requesting and signing, customizable templates, and a (limited in scope) sandbox via the option to send sample documents to yourself.

Available SDKs: Python, Ruby, PHP, Java, Node.js, C#

2. Electronic Signature API (Signature API)

SignatureAPI’s Electronic Signature API — here’s a brand you could never accuse of obscuring what they actually do(!) — is a lightweight solution built (in their words) “by developers, for developers.” It offers an API Playground as well as a Power Automate connector for no-code integrations if you’re looking to keep things as simple as possible.

Priced for scale and less expensive than some other solutions — its pricing page actively invites comparisons with Docusign and Dropbox Sign — it’s a solid choice for those seeking a “no frills” solution that remains fully compliant with eIDAS, UETA, the ESIGN Act, and so on.

Webhook libraries: JavaScript, Python, Java, Rust, Go, Ruby, PHP, C#, Elixir

3. Docusign API

When most people think of signing documents online, they probably think of Docusign. An early entry into the electronic signature space, founded back in 2003, it continues to be the dominant player today. Their scalable Intelligent Agreement Management (IAM) API goes way beyond eSignatures, including features like ID Verification with Liveness Detection to deter spoofing.

Other APIs that sit within Docusign’s suite of developer products include their Web Forms API, agreement storage and management via Navigator API, Maestro API for Docusign workflows, and Connect Webhooks to receive updates about specific triggering events. It’s a comprehensive solution, albeit one that might be a little daunting for inexperienced devs.

Available SDKs: C#, Java, Node.js, PHP, Python, Ruby, iOS, Android

4. Signicat

Signicat provides an all-in-one solution for signing, validating, storing, and managing signed documents. They also offer Digital Evidence Management, an auditing service for determining who signed what and when they signed it. Available via APIs and their web-based portal, they meet eIDAS regulation requirements for AES and QES.

In addition to eSignatures, they also provide eID and eIDV methods for tying identity verification more closely to signing solutions. Pricing for their solution(s) is a little more obscure than other platforms and requires getting in touch for a personalized quote.

Available SDKs: Java, .NET (core and Adapter), Mobile

5. Legalesign

Available via REST and GraphQL, Legalesign handles thousands of documents sent via their apps and API daily. Their API Dashboard provides a central control panel for managing requests and webhook logs, with a cut-and-paste code generator for getting started.

A free trial is available, along with pay-as-you-go “per document” and subscription plans. For more than 1,000 documents per month, you’ll need to contact Legalesign for a custom plan. The company declares itself to be API-first, exposing all of its functionalities — including document signing and witnessing, custom PDFs (and previews), webhook reporting, and so on — via API.

Available SDKs: TypeScript, JavaScript (.NET and Python on their roadmap)

6. Lumin Sign

Scalable and highly customizable (for Enterprise plan customers), Lumin Sign requires potential users to book a discovery call before they can start using the API in earnest. With that said, they offer a sandbox — that’s GDPR compliant and includes webhooks — and a free trial for up to 1,000 requests, which might be more than enough to keep some users going for a while.

Although their documentation is fairly thorough, it isn’t easily searchable and doesn’t feel quite as comprehensive as some other products on this list. Although their sandbox is great for discovery, it really feels like they want you to book a call with them to discuss your needs in detail. Which, perhaps, given their list of high-profile enterprise clients, shouldn’t be surprising.

Available SDKs: Not posted publicly

7. PandaDoc

Already handling millions of document actions for 60,000+ companies every month, PandaDoc is truly enterprise-grade and SOC 2 certified. Its secure signatures are ESIGN, UETA, GDPR, eIDAS, and HIPAA compliant, and the company has been ranked both Most Implementable and Leader in the eSignature space by G2.

Like Docusign, PandaDoc’s suite of APIs goes well beyond electronic signatures — including quote and contract generation, workflows including trigger actions, multi-step approvals, and various other workflows — and sits alongside a wide range of native integrations.

Available SDKs: Python, Node, Java, PHP, JavaScript

The Future of eSignature APIs

It’s telling that, while many of the products featured above are generally billed as eSignature APIs, many of them are also digital signature APIs. Several of them have a wider focus on identity verification, with eSign APIs representing just one part of their business models.

Although the terms are often used interchangeably, electronic signatures and digital signatures are not the same. All digital signatures are electronic signatures, but not all electronic signatures are digital signatures. The latter encrypts documents using digital codes for verifying the authenticity and integrity of documents, like a tamper-proof seal. If you’ve read up on decentralized identity, some of the concepts associated with digital signatures will sound familiar.

Just as many sites and apps have moved away from passwords towards passcodes, 2FA, and other authentication methods, this may indicate a shift away from electronic signatures as we currently know them towards a method of “signing” that looks a bit different. That shouldn’t be surprising given the ambiguity of the eSign Act’s wording, which features a flexible definition of signing that allows plenty of scope for interpretation.

We could be heading into a future of signing and ID verification built around token-based systems, selective proofs, the birth of a global decentralized identity ecosystem, or some combination of all of the above. But one thing’s for sure: eSignature APIs and digital signature APIs are likely to be a key ingredient in any shift to a new type of document signing and identity management.