eSignature API

Every request carries your API key in the Authorization header. There is no OAuth flow and no token to refresh. The base URL is https://app.quicksigner.com/api/v1.

1. Upload the document

Upload a PDF, DOC or DOCX file of up to 15 MB. The response gives you a fileName for the next call.

curl --request POST \
  --url https://app.quicksigner.com/api/v1/files \
  --header 'Authorization: YOUR_API_KEY' \
  --header 'Accept: application/json' \
  --header 'Content-Type: multipart/form-data' \
  --form file=@contract.pdf

# Response
{ "fileName": "a1b2c3d4-...-contract.pdf" }

2. Create the sign request

Name the signers and place their fields. QuickSigner emails each signer a secure link, and the response includes that link as signUrl.

curl --request POST \
  --url https://app.quicksigner.com/api/v1/requests \
  --header 'Authorization: YOUR_API_KEY' \
  --header 'Accept: application/json' \
  --header 'Content-Type: application/json' \
  --data '{
    "fileName": "a1b2c3d4-...-contract.pdf",
    "recipients": [
      {
        "type": "EMAIL",
        "email": "jane@example.com",
        "name": "Jane Doe",
        "fields": [
          { "type": "SIGNATURE", "pageNum": 1,
            "x": 100, "y": 600, "width": 180, "height": 60, "required": true }
        ]
      }
    ],
    "senderName": "Acme Corp",
    "emailSubject": "Please sign your contract"
  }'

# Response (abbreviated)
{ "id": "req_...", "status": "IN_PROGRESS",
  "recipients": [ { "id": "rcp_...", "signUrl": "https://app.quicksigner.com/sign/..." } ] }

3. Download the signed PDF and its certificate

Signatures are applied asynchronously, so wait for the REQUEST_COMPLETED webhook, then ask for the download links. Both calls return 403 until the request is completed.

# Signed PDF (link valid for about 2 hours)
curl --request GET \
  --url https://app.quicksigner.com/api/v1/requests/{requestId}/completed_download_url \
  --header 'Authorization: YOUR_API_KEY' \
  --header 'Accept: application/json'

# Signing certificate (link valid for about 15 minutes)
curl --request GET \
  --url https://app.quicksigner.com/api/v1/requests/{requestId}/download_certificate_url \
  --header 'Authorization: YOUR_API_KEY' \
  --header 'Accept: application/json'

# Each returns a short-lived download link
{ "requestId": "...", "docUrl": "https://..." }
{ "requestId": "...", "certificateUrl": "https://..." }

Load the signUrl of a signer in an iframe inside your own interface. The signer sees no redirect and no new tab, and the signed PDF is the same: the same PAdES seal and the same AATL certificate.

<iframe
  src="https://app.quicksigner.com/sign/..."
  width="100%" height="900" style="border:0"
  allow="camera; clipboard-write">
</iframe>

The interactive API reference has a “Try it” console for every endpoint. The developer guide on GitHub walks through each call with examples.

Testing is free. A developer account lets you create unlimited sign requests, and the completed documents carry a watermark.

Production runs on the Professional plan at $15 per user a month, or $144 per user a year when billed yearly. You pay $0.30 for each sign request, however many people sign it. The first 50 sign requests are free, once.

The table leaves out the 50 free sign requests. All plans are listed in the pricing section.

A signature made through the API is legally binding for most business documents. It is recognized under the US ESIGN Act and UETA and under eIDAS in the EU and UK. Some document types are excluded by law, such as wills and certain property transfers and court filings, so check the rules for those.

Three layers keep a signed PDF verifiable years later:

• PAdES. The signature is embedded inside the PDF, and any change made after signing is detectable.
• AATL certificate. The sealing certificate is on the Adobe Approved Trust List, so Adobe Acrobat and Reader show the signature as valid with no extra software.
• Trusted timestamp. A timestamp from a trusted time authority gives long-term validity, so the signature can still be verified after the signing certificate expires.

You can test this yourself. Complete a sign request, download the PDF and open it in Adobe Acrobat Reader. The signature panel should show a valid signature with no trust warnings.

QuickSigner is ISO/IEC 27001:2022 certified and GDPR compliant, and stores documents encrypted.