18.4
OpenSign is an open-source PDF e-signature solution for signing, storing, and securing documents.
Free planOpen sourceWebAPILinux
Best Electronic Signature APIs in 2026
Electronic signature APIs add signing flows to software. Compare support for embedded signing, signer authentication, webhooks, templates, signing order, bulk sending and maximum signers. Check the platforms before you build. The list includes APIs and services for Android, web, iOS, Windows and self-hosting; confirm that the option you choose covers your Android app or web workflow.
28.3
Free planAndroidiOSWeb
38.1
Free planAndroidiOSWeb
- 4
BoldSign
BoldSign is an electronic signature service for sending and managing documents, with templates, bulk sending, audit trails, SMS authentication, and signature ordering.
Free planAndroidiOSAPIExtension7.9From $5 a month - 5
Dropbox Sign API
Dropbox Sign API enables developers to add electronic signature workflows to their own websites and applications.
Free planAndroidiOSWebAPI7.4From $75 a month - 6
Signeasy
Signeasy is a document and contract service for signing, sending, tracking, and managing paperwork.
AndroidiOSWebAPI7.4From $10 a month - 7
Signority API
Signority API connects third-party integrations to Signority's eSignature and document workflow service through a RESTful API.
Free planWebAPISelf-hostedWindows7.2From $129 a year - 8
Documenso
Documenso provides electronic signature workflows for creating, sending, and signing documents.
Free planWebAPISelf-hosted7.0From $25 a month - 9
Assently API
AndroidiOSWebAPI6.7From €32 a month - 10
Signaturit
Signaturit is a paid digital transaction service from Signaturit Group, covering electronic signatures, identity verification, certificate…
WebAPI6.7From €9 a month - 11
Adobe Acrobat Sign
Adobe Acrobat Sign is a web- and API-based service for sending documents for electronic signature.
WebAPI6.6 - 12
DocuSign eSignature
DocuSign eSignature is a cloud service for sending, signing, and managing agreements.
API6.6From $11 a month - 13
Esig API
Free planWebAPI6.6From ₹20,000 a year - 14
Legalesign API
WebAPI6.6From £10 a month - 15
eSignatures.com API
WebAPI6.5 - 16
SignWell
Free planAPI6.5From $10 a month - 17
Blueink eSignature API
WebAPI6.4From $90 a month - 18
DocuSeal
DocuSeal is an e-signature service with document templates, bulk sending, API access, SMS authentication, and an audit trail.
Free planAPI6.4From $0.20 a month - 19
Sertifi
Sertifi provides hospitality-focused electronic signatures, payment collection, and digital authorization tools through the web and an API.
Free planWebAPI6.4Free plan - 20
ctSignature
WebAPI6.3From $29 a month - 21
Firma.dev
WebAPI6.3From €100 a month - 22
Scrive API
WebAPI5.9 - 23
signNow
API5.8From $1.50 a month - 24
Document eSign API
WebAPI5.7From $20 a month - 25
Namirial Sign
Namirial Sign is a freemium document-signing service from a maker founded in 2000 and headquartered in Senigallia, Italy.
Free planAPI5.7Free plan
Choosing well
Check platform fit
Review whether the service runs through an Android app, web interface, API, iOS or Windows. Self-hosted options can suit teams that want to run the service themselves.
An API may support a web workflow without providing an Android app, so verify how your phone or tablet users will access signing tasks.
Compare free and paid plans
A free plan can help you start without a subscription. Documenso, DocuSeal, Esig API and eSignatures.com API list free plans.
Check the paid starting point and billing terms. Listed examples include $10 for ctSignature, $20 per month for Document eSign API, $25 per month annually for Documenso and $90 per month annually for Blueink eSignature API.
Match the signing workflow
Compare embedded signing, signer authentication, templates and signing order. These controls affect how a document moves from your app to the people who must sign.
Bulk sending and maximum signers matter when one workflow covers many recipients. Check the documented limits for your process.
Plan integration and testing
Webhooks can notify your software about signing events. Confirm the events and integration details in the documentation before connecting a service.
A free trial is available from services on this list, and open-source code is available from services on this list. Check the licence and trial terms that apply to your choice.
Questions people ask
Do these electronic signature APIs work on Android?
Platform support varies. The category includes Android, web, iOS, Windows and self-hosted options. Check the platform details for the API or service you plan to use.
Can I start with a free plan?
Yes. Services on the list offer free plans, while others use paid or freemium pricing. Review the plan terms and included limits before integrating.
What should I compare besides price?
Compare embedded signing, signer authentication, webhooks, templates, signing order, bulk sending and maximum signers, along with the platforms you need.
Are free trials available?
A free trial is offered by services on the list. Trial length and conditions differ, so check the provider's current pricing details.
Is open-source code available?
Open-source code is offered by services on the list. Check the licence and whether self-hosting fits your deployment needs.