For signing a PDF, the most established option is the Docusign REST API, which can upload a document and send it to people to sign 1. Other sources offer PDF signing via API or MCP server: Siglio/Esigndev tags a PDF and sends it for e-signature 3, PDFGate collects legally binding e-signatures and seals completed documents 5, and PDF Generator API offers PDF form filling and encryption 7.
- 1
Docusign eSignature REST APIdocusign.netverified and signed
Uploads a document and sends it to one or more people to sign via DocuSign, using the createAndSendEnvelope action 1.
official:API · DocuSign REST API+5 community tools built for it
for agents: UserSignatures_PutUserSignature · UserSignatures_PostUserSignatures · createAndSendEnvelope
- 2
PDFGatepdfgate.comwebsite read, tools not yet checked
Collects legally binding electronic signatures on documents, recording each signer's consent and verifying recipients by email passcode, with an API and MCP server 5.
official:MCP server · @pdfgate/mcp-serverMCP server · com.pdfgate/mcp-server+1 community tools built for it
- 3
Siglioesigndev.comwebsite read, tools not yet checked
E-signature API that tags a PDF, sends it by email or SMS, and offers an MCP server for AI agents to send envelopes for signing 3.
official:MCP server · com.esigndev/siglio-mcp
- 4
PDF Generator APIpdfgeneratorapi.comverified and signed
Fills PDF form fields and encrypts PDF documents through its API, though its sources do not show it collecting signatures 7.
official:API · PDF Generator API
for agents: mergeTemplate · encrypt_document · fill_form_fields
Sources
- 1Docusign Developer Center | eSignature APIs & Resources | Docusigndevelopers.docusign.com · read just now
- 3Siglio | e-signature API for developers, 25¢ per envelopeesigndev.com · read 2026-10-29
- 5PDFGate - Create, Process, and Sign Documentspdfgate.com · read 2026-10-29
- 7PDF Generator API | Automate PDF document creationpdfgeneratorapi.com · read 2026-10-29
For agents: the 10 actions behind this answer
UserSignatures_PutUserSignature · DocuSign REST API verified and signed
Adds/updates a user signature.
· SignatureAPI Docs website read, tools not yet checked
Integrate electronic signatures into your apps and workflows with SignatureAPI's REST API, no-code connectors, and embedded signing solutions
· Esigndev website read, tools not yet checked
Electronic signature API for developers. 25 cents per envelope, flat. Email, SMS, or both. 25 free documents, no credit card, no monthly fee.
· PDFops website read, tools not yet checked
Fill, merge and inspect PDFs over HTTP — MCP server for AI agents, verified n8n node, pip install pdfops. Free to try: 100/IP/month keyless, free API key 250/mo. Paid from $16/mo.
· PDFGate website read, tools not yet checked
Generate PDFs, collect signatures, and manage documents through a simple dashboard or flexible API.
· Leafwright website read, tools not yet checked
Leafwright is an HTML to PDF API. POST HTML, a public URL, or a Handlebars template plus JSON data and get a signed download URL back — no Chromium in your serverless function. The same engine powers a document studio with AI drafts and brand kits.
mergeTemplate · PDF Generator API verified and signed
Generate document
create · doqs.dev | PDF filling API verified and signed
Create
downloadDocument · PandaDoc (Activepieces) verified and signed
Download Document — Downloads a document as PDF.
· Firma.dev website read, tools not yet checked
E-signature API for developers. GDPR-compliant, just 0.049 per envelope. Integrate in hours, not weeks. No contracts, no minimums.
Labels are the instruments' verdict and are never changed by ranking. Agents and robots get this same answer as JSON at /api/v1/find?q=…&answer=1 and through the MCP server.