License & Deployment Mix: 23 tools – 0 OSS, 18 SaaS. (OSS and SaaS counts can overlap when an open-source tool also offers a vendor-hosted edition.)

What Is E-Signature vs Digital Signature?

These terms are often used interchangeably but have distinct legal and technical meanings:

Electronic Signature (e-signature) is a broad legal term covering any electronic indication of intent to sign – a typed name, a drawn signature on a touchscreen, a checkbox, or clicking “I agree.” E-signatures are defined by legal frameworks, not by technology.

Digital Signature is a cryptographic mechanism that uses public-key cryptography to verify the signer’s identity and ensure the document has not been altered after signing. Digital signatures are a subset of e-signatures that provide stronger technical guarantees.

Signature Levels (eIDAS)

The EU’s eIDAS regulation defines three levels of electronic signatures:

• SES – any electronic data attached to or logically associated with other electronic data, used by the signatory to sign. No identity verification required.
• AES – uniquely linked to the signatory, capable of identifying the signatory, created using data under the signatory’s sole control, and linked to the signed data so any subsequent change is detectable.
• QES – an advanced electronic signature created by a qualified electronic signature creation device (QSCD), based on a qualified certificate issued by a trust service provider. QES has the legal equivalent of a handwritten signature across all EU member states.

Legal Frameworks

Most business-to-business e-signatures in the US and EU use SES or AES level, which all tools in this evaluation support. QES requires integration with qualified trust service providers (TSPs) and is relevant primarily for regulated industries and government contracts.

The information on these pages was researched by a combination of human review and large language models. To suggest an addition or correction, please contact us. Prepared by Rhodium Systems Inc., author of the ResorsIT platform — a unified IT operations management platform for IT teams and MSPs that integrates a curated suite of open-source, commercial, and SaaS applications into a single system with shared identity, single sign-on, access control, and a common audit trail. Use this catalogue only as a starting point for your own research, and review any tool carefully against your own requirements before relying on it. Catalogue data version 2026.197.

Comparison

E-signature carries legal weight (evidence in disputes, regulatory compliance, audit trail defensibility), which makes SaaS the preferred model for many buyers – commercial providers maintain compliance certifications (SOC 2, HIPAA, eIDAS QES), legal enforceability precedent, and tamper-evident infrastructure that self-hosted OSS tools cannot match.

ERP built-in signing: Odoo Enterprise includes a native Sign app (templates, multi-signer workflows, field placement, audit trail), which may cover e-signature needs without a separate tool.

SSO / OIDC Comparison

OIDC is the preferred SSO protocol.

* = requires specific plan, module, or configuration

Best SSO support: OneSpan Sign (OIDC + SAML + LDAP), BoldSign (OIDC + SAML), Documenso (native OIDC), DocuSign (OIDC/SAML)

No SSO: OpenSign, SignServer CE, SignWell, HoloSign, Agrello, DocuSeal (reverse-proxy only)

API Comparison

* = limited or requires paid tier

Best API: DocuSign (7 SDKs, Connect webhooks, multiple embed options), BoldSign (4 SDKs, full REST), Dropbox Sign (5 SDKs), SignNow (5 SDKs)

Best OSS API: DocuSeal (REST + iframe embed), Documenso (REST + React components)

E-Signature Capabilities

* = eIDAS QES support via TSP integration

Note: SignServer CE is a pure cryptographic signing server – it does not provide document workflow features (field placement, templates, bulk send). It is included because it provides server-side digital signature capabilities that can be integrated into custom workflows.

Bulk Signing Capabilities

Bulk signing is critical for high-volume scenarios (annual policy renewals, onboarding cohorts, vendor agreements). Not all “bulk send” features are equal – key differentiators are batch size, CSV merge fields, per-recipient status tracking, and API support.

* = self-hosted; batch size limited by server resources, not software cap

Bulk send is a key differentiator between tools. PandaDoc, Documenso, and OpenSign lack bulk send entirely. For organizations with annual renewal or onboarding workflows that send hundreds of identical documents, this is often a dealbreaker.

Deployment and Licensing

* = self-hosted or on-premises option available on specific plans or editions

Cost note: Self-hosted OSS tools (DocuSeal, Documenso, OpenSign, Open eSignForms) eliminate per-envelope fees entirely. For organizations sending hundreds or thousands of documents per month, this represents significant savings vs SaaS tools that charge $1-5 per envelope.

DocuSeal API note: Self-hosting is free, but the embedded signing API and certain advanced API features require the Pro license ($20/month). Basic API access (create, send, download) is available in the free self-hosted version.

Compliance / Legal Validity

* = depends on configuration, certificates, or integration with qualified TSPs

Best compliance: DocuSign, Adobe Sign, OneSpan Sign (all three support QES with qualified TSP integration, HIPAA, SOC 2)

Self-hosted data residency note: OSS tools give full control over data residency, retention, and deletion – simplifying GDPR compliance without requiring vendor DPAs. However, for e-signatures the legal enforceability benefits of SaaS (SOC 2, court precedent, expert witness support) outweigh data residency advantages. Self-hosted OSS e-sign tools remain an option for customer deployments where the customer accepts compliance responsibility.

Tools

23 tools.

Adobe Acrobat Sign

Adobe Acrobat Sign (formerly Adobe Sign, and before that EchoSign) is Adobe’s enterprise e-signature platform, integrated into the Adobe Document Cloud alongside Acrobat Pro.

License: Proprietary (proprietary) · Kind: web · Deploy: native, saas · SSO: OIDC

Website

Agrello

Agrello is an Estonian e-signature platform focused on EU eIDAS compliance and strong digital identity verification.

License: Proprietary (proprietary) · Kind: web · Deploy: saas · SSO: none

Website

BoldSign

BoldSign is an e-signature platform built by Syncfusion, a well-established developer tools company known for its UI component libraries for .NET, JavaScript, and other frameworks.

License: Proprietary (proprietary) · Kind: web · Deploy: native, saas · SSO: OIDC

Website

Contractbook

Contractbook is a contract lifecycle management (CLM) platform with integrated e-signatures, based in Denmark.

License: Proprietary (proprietary) · Kind: web · Deploy: saas · SSO: none

Website

Documenso

Documenso is a modern open-source e-signature platform built on Next.js and TypeScript. It positions itself as the open-source alternative to DocuSign, with a focus on transparency, developer experience, and modern web standards.

License: AGPL-3.0-only (OSS) · Kind: web · Deploy: native · SSO: OIDC

Website · Source

DocuSeal

DocuSeal is the most feature-complete open-source e-signature platform available. It provides document templates with drag-and-drop field placement, bulk send for high-volume signing, sequential and parallel signing workflows, and a compreh…

License: AGPL-3.0-only (OSS) · Kind: web · Deploy: native · SSO: none

Website · Source

DocuSign

DocuSign is the global market leader in electronic signatures, with over one billion users and more than a million paying customers across 180+ countries.

License: Proprietary (proprietary) · Kind: web · Deploy: native, saas · SSO: OIDC

Website

DottedSign

DottedSign is an e-signature product from Kdan Mobile, a Taiwanese software company known for mobile productivity tools.

License: Proprietary (proprietary) · Kind: web · Deploy: native, saas · SSO: none

Website

Dropbox Sign

Dropbox Sign (formerly HelloSign) is a developer- friendly e-signature platform acquired by Dropbox in 2019 for approximately $230 million.

License: Proprietary (proprietary) · Kind: web · Deploy: native, saas · SSO: none

Website

Formstack Sign

Formstack Sign is the e-signature component of the Formstack platform, which also includes Formstack Forms (online form builder) and Formstack Documents (document generation).

License: Proprietary (proprietary) · Kind: web · Deploy: saas · SSO: none

Website

GetAccept

GetAccept is a sales enablement platform that combines e-signatures with proposals, document tracking, and video messaging.

License: Proprietary (proprietary) · Kind: web · Deploy: saas · SSO: none

Website

HoloSign

HoloSign is an affordable, user-friendly e-signature platform targeting freelancers and small businesses.

License: Proprietary (proprietary) · Kind: web · Deploy: saas · SSO: none

Website

OneSpan Sign

OneSpan Sign (formerly eSignLive, originally Silanis) is an enterprise-grade e-signature platform with a strong focus on security, compliance, and the financial services industry.

License: Proprietary (proprietary) · Kind: web · Deploy: native, saas · SSO: OIDC

Website

Open eSignForms

Open eSignForms is a mature Java-based e-signature platform and one of the oldest open-source options in this category.

License: AGPL-3.0-only (OSS) · Kind: web · Deploy: native · SSO: none

Website · Source

OpenSign

OpenSign is a simple open-source e-signature platform built on React and Node.js with a MongoDB backend. It provides core signing functionality including templates, multi-signer sequential workflows, and audit trails.

License: AGPL-3.0-only (OSS) · Kind: web · Deploy: native · SSO: none

Website · Source

PandaDoc

PandaDoc is a document automation platform that combines e-signatures with proposals, quotes, contracts, and forms in a single product.

License: Proprietary (proprietary) · Kind: web · Deploy: native, saas · SSO: none

Website

Signeasy

Signeasy is a mobile-first e-signature platform that originated as an iOS application and has expanded to a full web-based signing solution.

License: Proprietary (proprietary) · Kind: web · Deploy: saas · SSO: none

Website

SigniFlow

SigniFlow is a South African e-signature and digital workflow platform offering on-premises, private cloud, and SaaS deployment options.

License: Proprietary (proprietary) · Kind: web · Deploy: native, saas · SSO: OIDC

Website

SignNow

SignNow is an e-signature platform that is part of the airSlate Business Cloud, a broader document workflow automation ecosystem.

License: Proprietary (proprietary) · Kind: web · Deploy: native, saas · SSO: none

Website

SignServer CE (Community Edition)

SignServer CE is a server-side cryptographic signing engine developed by Keyfactor (formerly PrimeKey).

License: LGPL-2.1-or-later (OSS) · Kind: web · Deploy: native · SSO: none

Website · Source

SignWell

SignWell is a simple, affordable e-signature platform designed for small businesses and individuals who need straightforward document signing without enterprise complexity.

License: Proprietary (proprietary) · Kind: web · Deploy: saas · SSO: none

Website

Yousign

Yousign is a French e-signature platform founded in 2013 and headquartered in Paris. It is one of the leading e-signature providers in Europe, with a strong presence in France, Germany, and across the EU.

License: Proprietary (proprietary) · Kind: web · Deploy: native, saas · SSO: none

Website

Zoho Sign

Zoho Sign is the e-signature module within the Zoho ecosystem, a suite of 50+ business applications including Zoho CRM, Zoho Books, Zoho People, Zoho Creator, and Zoho Desk.

License: Proprietary (proprietary) · Kind: web · Deploy: native, saas · SSO: none

Website