> ## Documentation Index
> Fetch the complete documentation index at: https://docs.thesignproof.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> E-signature infrastructure for developers. Add legally binding document signing to any product in minutes.

## What is SignProof?

SignProof is an API-first e-signature service. You send us a PDF and a list of signers — we handle
the signing links, identity verification, and return you a cryptographically sealed PDF with a full
audit trail.

Every completed document includes:

* **SHA-256 hash** of the original and final PDF (tamper-detectable)
* **PKCS#7 digital seal** — any byte change is detectable in Adobe Acrobat
* **RFC 3161 trusted timestamp** — proves the seal time even after certificate rotation
* **Hash-chained audit log** — append-only, detectable even with direct database access
* **Full audit certificate page** appended to the sealed PDF

SignProof is PIPEDA-compliant (Canada) and ESIGN/UETA-compliant (United States).

## Who is it for?

SignProof is built for developers integrating e-signatures into their own products — not for
end-users who want to sign documents manually. If you want a consumer signing app, use DocuSign.
If you want to build one, use SignProof.

**Typical use cases:**

* **SaaS platforms** — add signing to your existing product flow
* **Healthcare** — patient consent forms, intake documents
* **Legal tech** — engagement letters, NDAs
* **Real estate** — lease agreements, offers

## How it works

<Steps>
  <Step title="Create an envelope">
    Upload a PDF, define fields (signature, date, text), and specify signers with routing order.
  </Step>

  <Step title="Send">
    SignProof generates a tokenized signing link for each signer and dispatches email/SMS invites.
  </Step>

  <Step title="Signers sign">
    Each signer opens their link, verifies identity via OTP, consents to e-signature, and completes
    their fields.
  </Step>

  <Step title="Sealed PDF delivered">
    When all signers complete, SignProof seals the PDF, appends the audit certificate, and fires a
    webhook to your endpoint with the download URL.
  </Step>
</Steps>

## Base URL

```
https://api.thesignproof.com
```

All endpoints are versioned under `/v1/`.

## Next steps

<CardGroup cols={2}>
  <Card title="Quickstart" icon="bolt" href="/quickstart">
    First sealed PDF in under 5 minutes
  </Card>

  <Card title="Authentication" icon="key" href="/authentication">
    Get your API credentials and mint a token
  </Card>

  <Card title="Envelopes" icon="envelope" href="/guides/envelopes">
    Understand the envelope lifecycle
  </Card>

  <Card title="Webhooks" icon="webhook" href="/guides/webhooks">
    React to signing events in real time
  </Card>
</CardGroup>