# SigPen

> SigPen is an electronic signature platform with a REST API (v1, additive-only) for sending documents for signature, embedding signing in your own app, and receiving signed webhook events. Base URL: https://www.sigpen.com/api/v1. Authenticate with `Authorization: Bearer sp_live_...` or `X-API-Key`. Test keys (`sp_test_`) don't count toward quotas. SigPen also offers AI field detection (its AI places signature, date, and initial fields in the editor) and Siggy, an in-app AI assistant.

## AI features

- AI field detection: in the editor, upload a PDF and click AI Detect, and SigPen places signature, date, initial, text, and checkbox fields for you with AI. Included on the free trial and paid plans, with a monthly limit by plan. Details: https://www.sigpen.com/ai-field-detection
- Siggy: an in-app AI assistant that answers product and account questions.

## API reference

- [Documents](https://www.sigpen.com/docs/api/documents): Upload PDFs, track status, void, download the signed result, and clean up drafts. Documents are the core object in the SigPen API. Endpoints: GET /documents, POST /documents, GET /documents/{id}, DELETE /documents/{id}, POST /documents/{id}/void, GET /documents/{id}/download
- [Signing](https://www.sigpen.com/docs/api/signing): Send a document to one or more signers and nudge them along. Place fields inline per signer, no visual editor required. Endpoints: POST /documents/{id}/send, POST /documents/{id}/remind
- [Embedded Signing](https://www.sigpen.com/docs/api/embedded-signing): Generate short-lived signing URLs to embed the signing experience in your own app with embed.js or an iframe. Endpoints: POST /documents/{id}/embedded-sign-url
- [Templates](https://www.sigpen.com/docs/api/templates): Reusable documents with role-based fields. Create them once, then mint pre-filled documents from them by API. Endpoints: POST /documents/from-template, GET /templates, POST /templates, GET /templates/{id}, PATCH /templates/{id}, DELETE /templates/{id}
- [Webhooks](https://www.sigpen.com/docs/api/webhooks): Receive signed event notifications when documents are sent, viewed, completed, voided, or expired. Endpoints: GET /webhooks, POST /webhooks, GET /webhooks/{id}, PATCH /webhooks/{id}, DELETE /webhooks/{id}, POST /webhooks/{id}/test
- [Bulk Send](https://www.sigpen.com/docs/api/bulk-send): Send one document to many recipients at once. Each recipient gets their own copy and signing session. Endpoints: POST /documents/{id}/bulk-send, GET /bulk-sends/{id}
- [Forms Library](https://www.sigpen.com/docs/api/forms): Browse SigPen’s library of legal form templates and create ready-to-send documents from them. Endpoints: POST /documents/from-form, GET /forms, GET /forms/{id}
- [Account](https://www.sigpen.com/docs/api/account): Inspect the authenticated account: plan, usage, and API capabilities. Endpoints: GET /account

## Machine-readable

- [OpenAPI spec (JSON)](https://www.sigpen.com/openapi.json): full schema for codegen and tooling
- [OpenAPI spec (YAML)](https://www.sigpen.com/openapi.yaml): same spec, YAML original
- [llms-full.txt](https://www.sigpen.com/llms-full.txt): expanded endpoint reference in one file
- [API changelog](https://www.sigpen.com/changelog): dated changes, additive-only promise, RSS at /changelog/rss.xml

## Product

- [Developers](https://www.sigpen.com/developers): free sandbox key, quickstart, plan limits
- [Pricing](https://www.sigpen.com/pricing): plans and feature comparison
- [Form library](https://www.sigpen.com/forms): legal form templates, fillable and signable online
- [Best E-Signature Software 2026](https://www.sigpen.com/best-e-signature-software): honest roundup of SigPen, DocuSign, PandaDoc, Dropbox Sign, and signNow
- [SigPen vs DocuSign](https://www.sigpen.com/vs-docusign): flat monthly pricing vs per-envelope fees
- [SigPen vs PandaDoc](https://www.sigpen.com/vs-pandadoc): flat per-account pricing vs per-seat billing
- [SigPen vs HelloSign](https://www.sigpen.com/vs-hellosign): flat pricing and bundled API vs per-seat plans and a separate API product
- [SigPen vs signNow](https://www.sigpen.com/vs-signnow): flat team pricing and a bundled API vs per-seat plans and a separate API product