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OpenSign

opensignlabs.com

From $9.99/mo Free plan Open source WebWindowsmacOSLinuxAPISelf-hosted
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Spec score 9.0 #4 of 68 in E-Signature Software

What it is

OpenSign is an open-source PDF e-signature solution for signing, storing, and securing documents. Users can create reusable templates with pre-placed widgets and send them through the API to one or many signers. API workflows include self-signing, drafts, signer roles, public template links, and real-time webhook notifications. Templates can be embedded in React, Next.js, HTML, JavaScript, and Angular projects. The documentation lists TLS-encrypted transport, audit trails, IP logging, and tamper-evident signed PDFs; account protection includes two-factor authentication and passkey sign-in. The free plan costs nothing and lists unlimited digital signatures and templates, completion certificates, sequential signing, OpenSign Drive, and email notifications. Its free-plan guide limits invitation emails to 15 per month; bulk sending and public links require a paid plan. Live API tokens require Professional or Teams, though sandbox tokens are available on all plans. OpenSign provides Docker self-hosting instructions for Linux, macOS, and Windows. Some SMTP features are limited to paid plans.

Spec sheet

What it does
OpenSign provides cloud and self-hosted electronic document signing for creating, sending, signing, storing and tracking documents.Read 15 Oct 2026 · docs.opensignlabs.com
Product
OpenSign describes itself as an open-source PDF e-signature solution for signing, storing, and securing documents.Read 9 Oct 2026 · opensignlabs.com
Intended users
The documentation describes the product as designed for individuals and businesses, from startups to large corporations.Read 9 Oct 2026 · docs.opensignlabs.com
Free plan
YesRead 20 Sep 2026 · opensignlabs.com
API
OpenSign exposes a REST API authenticated with an x-api-token header and provides sandbox, production and EU endpoints.Read 15 Oct 2026 · docs.opensignlabs.com
Integrations
The Professional plan lists Zapier integration, Dropbox import and custom Gmail or SMTP sending.Read 15 Oct 2026 · www-opensignlabs-com.filesusr.com
Security
The API documentation lists TLS-encrypted transport, audit trails, IP logging, and tamper-evident signed PDFs.Read 9 Oct 2026 · docs.opensignlabs.com
Support
The documentation directs users to contact OpenSign support at [email protected] for assistance.Read 9 Oct 2026 · docs.opensignlabs.com
Account protection
OpenSign provides two-factor authentication and passkey sign-in options.Read 9 Oct 2026 · docs.opensignlabs.com
API access
YesRead 20 Sep 2026 · opensignlabs.com
API capabilities
The API can create, send, update, revoke and delete documents, manage templates, contacts and folders, and receive webhooks.Read 15 Oct 2026 · docs.opensignlabs.com
API compatibility
The v1.2 API states that it is backward compatible with v1 and v1.1 and keeps earlier endpoints available.Read 15 Oct 2026 · docs.opensignlabs.com
API extensibility
API v1.2 adds attachment widgets, password-protected PDFs, offline-signing controls, signer roles and carbon-copy recipients.Read 15 Oct 2026 · docs.opensignlabs.com
API limit
Live API tokens require a Professional or Teams plan, while sandbox tokens are available on all plans.Read 9 Oct 2026 · docs.opensignlabs.com
Audit trail
YesRead 20 Sep 2026 · opensignlabs.com
Bulk sending
YesRead 20 Sep 2026 · opensignlabs.com
Company founding
The LinkedIn company page does not state a founding year.Read 15 Oct 2026 · linkedin.com
Company headquarters and size
LinkedIn lists OpenSign Labs as privately held, headquartered in New York, with 2–10 employees.Read 15 Oct 2026 · linkedin.com
Company identity
The privacy policy identifies Qik Innovations Private Limited as the operator of OpenSign.Read 15 Oct 2026 · opensignlabs.com
Completion certificates
Version 1.5.0 added an automatically digitally signed completion certificate after all signers finish.Read 15 Oct 2026 · opensignlabs.com
Document templates
YesRead 20 Sep 2026 · opensignlabs.com
Document widgets
The product supports signature, initials, text, date, checkbox, stamp and number widgets, with number calculations.Read 15 Oct 2026 · docs.opensignlabs.com
Documentation
The official documentation includes user help, API references, contribution guidance and self-hosting instructions.Read 15 Oct 2026 · docs.opensignlabs.com
Email
Users can configure SMTP, including Gmail and third-party SMTP providers, and some SMTP features are limited to paid plans.Read 9 Oct 2026 · docs.opensignlabs.com
Expiring links
Signed PDF download links are designed to expire after a few minutes.Read 15 Oct 2026 · opensignlabs.com
Free plan limit
The maker’s free-plan guide says users can send up to 15 invitation emails per month; bulk sending and public links require a paid plan.Read 9 Oct 2026 · opensignlabs.com
Identity verification
OpenSign documents can require email OTP verification and access codes before recipients view or sign.Read 15 Oct 2026 · docs.opensignlabs.com
Latest release
GitHub release v2.40.0 added an attachments widget, API attachment support and an option to hide signer links in draft-document responses.Read 15 Oct 2026 · github.com
Licence
The source code and API documentation identify the project as licensed under GNU AGPL v3.0.Read 15 Oct 2026 · github.com
Limit: field deletion
A Capterra reviewer reported that accidentally added fields could not be deleted.Read 15 Oct 2026 · capterra.com
Limit: form controls
A Capterra reviewer reported that radio-button controls need improvement and that document preview before sending would be useful.Read 15 Oct 2026 · capterra.com
Limit: free-plan invitations
The free plan limits invitation emails to 15 per month, while paid plans remove that limit.Read 15 Oct 2026 · opensignlabs.com
Limit: localization
A Capterra reviewer complained that OpenSign did not support multiple languages.Read 15 Oct 2026 · capterra.com
Limit: paid credits
API, bulk-send, public-link, kiosk and embedded workflows consume premium credits, with additional credits priced at $0.15 each.Read 15 Oct 2026 · opensignlabs.com
Limit: SMTP bug
A G2 reviewer using Docker self-hosting reported SMTP incompatibility when emails use the signer address and said the bug remained unresolved.Read 15 Oct 2026 · g2.com
Limit: support reliability
A Trustpilot reviewer said paid templates were sometimes sent blank and reported support stopped responding for more than a month.Read 15 Oct 2026 · trustpilot.com
Notable news
OpenSign announced version 1.5.0 on June 12, 2024 with custom email templates, revoke controls, enterprise branding, API enhancements and usage analytics.Read 15 Oct 2026 · opensignlabs.com
Praise: ease of use
Independent reviewers repeatedly describe the interface as intuitive, simple, straightforward and easy to train others on.Read 15 Oct 2026 · capterra.com
Praise: self-hosting
Reviewers highlight self-hosting as a benefit for local control and customization.Read 15 Oct 2026 · capterra.com
Praise: value
Reviewers repeatedly praise OpenSign as affordable or free compared with DocuSign and other alternatives.Read 15 Oct 2026 · g2.com
Rating on Capterra
4.7 out of 5 from 3 reviews.Read 15 Oct 2026 · capterra.com
Rating on G2
4.6 out of 5 from 12 reviews.Read 15 Oct 2026 · g2.com
Rating on Gartner Peer Insights
Gartner Peer Insights lists OpenSign but shows no reviews yet.Read 15 Oct 2026 · gartner.com
Rating on GetApp
4.7 out of 5 from 3 reviews.Read 15 Oct 2026 · getapp.com
Rating on Trustpilot
3.6 out of 5 from 4 reviews.Read 15 Oct 2026 · trustpilot.com
Security authentication
The service documents two-factor authentication and passkey login options.Read 15 Oct 2026 · docs.opensignlabs.com
Self-hosting
OpenSign can be deployed with Docker on Linux, macOS or Windows using Docker Compose, MongoDB and S3-compatible or local storage.Read 15 Oct 2026 · docs.opensignlabs.com
Self-hosting warning
The Docker guide warns that the default MongoDB configuration has authentication disabled and port 27017 must not be exposed publicly.Read 15 Oct 2026 · docs.opensignlabs.com
Sequential signing
Documents can require signers to complete in a defined order or allow simultaneous signing.Read 15 Oct 2026 · docs.opensignlabs.com
Signature order
bothRead 20 Sep 2026 · opensignlabs.com
SMS authentication
YesRead 20 Sep 2026 · opensignlabs.com
Support channels
Documentation links users to GitHub Discussions, Discord, Twitter, LinkedIn and Facebook communities.Read 15 Oct 2026 · docs.opensignlabs.com
Templates
Users can create reusable templates with pre-placed widgets and send them to one or many signers through the API.Read 9 Oct 2026 · docs.opensignlabs.com
Workflows
The API supports self-signing, public template links, drafts, signer roles, and real-time webhook notifications.Read 9 Oct 2026 · docs.opensignlabs.com

Plans and prices

Free Free Free for life Unlimited digital signatures · Unlimited templates · Completion certificates · Sequential signing · OpenSign Drive · Email notifications Read 15 Oct 2026 · www-opensignlabs-com.filesusr.com
Professional $9.99 a month Monthly Field validations · Calculated fields · Webhooks · Zapier integration · API access · 240 premium credits per year · Up to 10 signers per document · Embedded signing · Public links Read 15 Oct 2026 · www-opensignlabs-com.filesusr.com
Teams $19.99 a month Per user per month Everything in Professional · Up to 500 API signatures included · Team features Read 15 Oct 2026 · www-opensignlabs-com.filesusr.com
Free Free All for Free Unlimited e-signatures · free invitations and collaboration · completion certificates with access logs · OpenSign Drive storage Read 9 Oct 2026 · opensignlabs.com
Enterprise Priced on request Contact sales Custom domain · Whitelabeling · Uptime SLA · SSO support · Priority support Read 15 Oct 2026 · www-opensignlabs-com.filesusr.com

Every OpenSign plan and price →

Strong points and limits

Strong points

  • Free plan lists unlimited signatures and templates.
  • Supports audit trails and tamper-evident signed PDFs.
  • Sandbox API tokens are available on all plans.
  • Docker self-hosting instructions cover Linux, macOS, and Windows.

Limits

  • Free plan limits invitation emails to 15 per month.
  • Bulk sending and public links require a paid plan.
  • Live API tokens require Professional or Teams.
  • Some SMTP features are limited to paid plans.

Who it suits

OpenSign is described as suitable for individuals and businesses, from startups to large corporations. Its API workflows and self-hosting options may suit teams embedding signing into applications or deploying the service themselves.

Verdict

OpenSign offers document signing through templates and API workflows, with self-hosting instructions and account protections. The free plan lists unlimited signatures, but its monthly invitation email limit and paid-plan requirements for bulk sending and live API tokens are important constraints.

Where Specifiction places it

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