Integration architecture: choose a pattern

This section is for architects integrating LibreSign into an existing application. LibreSign is free and open-source software; deploying it does not require a commercial service. Optional hosting, support and third-party delivery gateways are separate from the LibreSign API. Your application may retain its UI, authentication and business workflow.

You are reading the guide for LibreSign 13.4.9 on Nextcloud 33. Concepts here apply to the available release line; the OpenAPI contract is version-specific. Confirm each request shape in OCS OpenAPI — versioned contract before implementing it.

Start with your constraint

Integration decision matrix

Situation	Preferred approach	Benefit	Risk or limitation	Requirements
Existing product must keep its UI and login	Product backend orchestrates LibreSign via authenticated OCS requests	No Nextcloud UI migration	Backend credentials are powerful; signer actions still need signer authority	Authorized Nextcloud principal; API and storage access
Signers already have Nextcloud accounts	Account identification; use their own login/session or approved token	Reuses account identity and access policies	Product login alone is not proof of a Nextcloud signer session	Mapped account; enabled signing method
Signer has no Nextcloud account	Email identification and LibreSign-controlled public signing invitation	No Nextcloud account provisioned for the signer	Invitation possession and email verification policies must be protected	Email method, approved verification flow, delivery
Internal and external signers share a document	Mixed signer identification in one request or envelope	One auditable workflow with distinct signer identities	Different tokens, signing order and completion states	All selected identify methods and policies enabled
Your product owns message delivery	Defer invitations with signer notify: 0; trigger LibreSign notifications later or use a verified integrator delivery flow	Controlled delivery timing and branding	No generic invitation-link retrieval contract is proven; never derive a URL from a UUID	Permitted requester, validated delivery flow and secure secrets
External service needs completion signals	Poll authorized OCS file status; use a native completion event only where this release publishes one	Reliable reconciliation, with optional lower-latency signals	Native events are version-gated and HTTP delivery needs deployment testing	Authorized status reader and, optionally, Nextcloud Webhook Listeners

Read the relevant guide

• Integrate an existing application without replacing its UI
  • Typical control and signer paths
  • Choose the signer model
  • API boundary and version differences
  • Integration responsibilities
• Account integration and authentication choices
  • Security boundaries
  • Authenticated OCS request (read-only)
  • Nextcloud references
• Notifications, completion and document recovery
  • Notification ownership
  • What counts as complete?
  • Polling and reconciliation
  • Native webhooks: version-specific completion events
  • Recover the final PDF and evidence
• Infrastructure, administration and policy preflight
  • Administrative questions to settle first
  • Production smoke checks

• Integrate an existing application without replacing its UI — retain the product UI; choose account, external, or mixed signers; orchestrate without impersonation.

• Account integration and authentication choices — distinguish Nextcloud accounts, App Passwords, OAuth2, OIDC and SSO.

• Notifications, completion and document recovery — notification ownership, state reconciliation, native webhook readiness and authorized document retrieval.

• Infrastructure, administration and policy preflight — infrastructure, permissions, certificates, policy decisions and go-live checks.

• External email signers: integration — version-specific, runnable email-signer integration with fixture selection and authorized PDF retrieval.

• OCS OpenAPI — versioned contract — the actual API schema for this release, including required properties and supported responses.

Contract and ownership boundaries

Practical API integration is already documented in External email signers: integration, with examples and tests pinned to each published LibreSign release. Use that guide for requests, mail invitations, status polling, validation and authenticated WebDAV download.

Native webhook support is release-dependent. Consult Notifications, completion and document recovery for the event availability on this release and the release-specific Webhooks manual where one exists. A compiled application event or passing unit test alone does not prove successful outbound HTTP delivery.

No recommendation here requires direct database access, credential sharing with a signer, or disabling Nextcloud authorization. Use supported OCS and Nextcloud file APIs instead.

For details of Nextcloud’s request transport, see the Nextcloud OCS API overview.