Digital signature API for enterprise PDF signing.
A document signing API and eSign API that runs on your infrastructure. This PDF signing API supports Aadhaar eSign API integration, REST API for digital signature, and on-premise deployment. Your documents never leave your premises.
Three steps.
All on your servers.
Your internal application sends a PDF to SignLift running on your infrastructure. SignLift signs it with your certificates and returns the sealed document. Nothing leaves your network.
Your app sends a PDF
Your internal application sends the PDF to the SignLift service running on your own server. Up to 50MB per file. Standard HTTPS, any language.
POST /v1/signSignLift signs it on-premise
The document is validated, your organization's PFX/P12 certificate is applied, and the signature is cryptographically embedded. All within your network.
Your certificatesSigned PDF returned instantly
The signed, tamper-evident PDF is returned to your application. No data ever left your premises. Verify integrity anytime through the verification endpoint.
Legally valid signatureSub-second response
Average signing time including upload and certificate application.
Batch processing
Sign up to 100 documents in a single API call with parallel processing.
HTTPS encrypted
Every byte is encrypted in transit. Your documents never touch an insecure channel.
You decide where
the signature lands.
Two intelligent placement strategies to handle any document structure. From rigid government forms to dynamic, template-generated contracts.
Coordinate Placement
Pixel-perfect precision
Specify exact X/Y coordinates and page number. Ideal for standardized documents where the signature always goes in the same spot: invoices, purchase orders, and government forms.
Text Search
Find text, sign beside it
SignLift scans your PDF for anchor text like "Authorized Signatory" and places the signature relative to it. Perfect when layouts vary but the anchor text stays consistent.
Built for enterprises
that own their data.
Cloud signing services require your documents to leave your network. SignLift deploys inside your infrastructure. Your PDFs, your certificates, your servers — nothing leaves the perimeter.
Documents never leave your network
Zero data leakagePDFs are signed on your servers, inside your firewall. No data is transmitted to external cloud services. Ideal for financial institutions, government agencies, and regulated industries where data residency is non-negotiable.
Your certificates, your control
Full key custodyLoad your organization's PFX/P12 certificates directly. Private keys stay on infrastructure you own and manage. Full chain-of-custody for compliance audits.
Works in air-gapped environments
Air-gap compatibleSignLift runs as a standalone service with no external dependencies. Deploy in isolated networks, secure government facilities, or restricted enterprise zones where outbound internet is blocked.
Audit trail under your control
Compliance-readyEvery signing operation is logged locally. Integrate with your SIEM, compliance dashboards, or internal audit systems. Retention policies, access logs, and certificate usage reports — all on your infrastructure.
Frequently asked questions
Everything you need to know about SignLift's server-side PDF signing API.
SignLift is a server-side digital signature API and eSign API for digitally signing PDFs. You send a PDF to our HTTPS endpoint, specify where to place the signature, and receive a signed PDF in response. Everything happens on our servers with no client-side libraries, no browser plugins, and no local certificate management required.
SignLift supports PFX/P12 certificate files and server-side signing certificates. You upload your organization's digital signature certificate to your SignLift account, and it is used for all document signing API operations. USB DSC tokens are not supported directly. For USB token signing, use SignBolt (desktop) or SignBridge (browser-to-token bridge).
Text-search placement scans the PDF for a specific text string (like "Authorized Signatory" or "Sign Here") and places the digital signature relative to that text. You can configure X/Y offsets from the found text position. This is ideal for documents where the layout varies but anchor text is consistent, such as template-generated invoices or contracts.
Maximum file size is 50MB per PDF. Standard API plans allow 100 requests per minute with burst support up to 200 requests. Batch signing supports up to 100 documents per request. For higher limits, contact sales for an enterprise plan with custom rate limits and dedicated infrastructure.
Yes. SignLift is designed for production workloads. The API runs on your infrastructure with enterprise-grade reliability. Batch signing endpoints process up to 100 documents in parallel per request. Sub-second response times at scale.
SignLift uses Bearer token authentication. You receive a test API key and a live API key when you create an account. Test keys work against a sandbox environment with watermarked signatures. Live keys produce legally valid signed documents. API keys can be rotated at any time from the dashboard.
SignLift uses usage-based pricing. You pay per API call (signing or verification operation). Volume discounts apply at higher tiers. A free sandbox environment is available for development and testing. Contact sales for production pricing tailored to your expected volume.
Yes. The /v1/verify endpoint accepts a signed PDF and validates the digital signature integrity, certificate chain, and timestamp. It returns detailed verification results including the signer identity, signing time, certificate validity, and whether the document has been tampered with after signing.
Your documents deserve
real signatures.
Get your API key and sign your first PDF in under 5 minutes. Free sandbox environment for development and testing. Production-grade infrastructure from day one.
Server-side signing · HTTPS encrypted · Bearer token auth · JSON responses · 99.9% uptime