eSignature API
REST eSign API. AATL-certified, PAdES-sealed, ISO 27001 secure
eSignature API
Legally Binding
Add legally binding electronic signatures to your app with a simple REST API. Our electronic signature is AATL-certified, PAdES-sealed, ISO 27001 secure. All you need is a Pro plan + $0.30 per document.
What Is An eSignature API?
An eSignature API lets your application send documents and collect legally binding electronic signatures — without your users ever leaving your product.
You upload a file, add signers, and the API returns a signed, AATL-certified PDF with a full audit trail.
Upload
Send a PDF or Word file through the API.
Add signers
Define signers, order and fields. Each signer gets a secure link — no account needed.
Get the signed PDF
When everyone has signed, you receive the sealed, AATL-certified PDF and its audit trail.
Signatures Sealed With Adobe (AATL)
Every signature you collect through the API is sealed with our certificate-based seal on the Adobe Approved Trust List (AATL).
Open the signed PDF in Adobe Acrobat or Reader and it shows the green check: “Signature is valid.” No warnings, no extra software.
AATL-certified
QuickSigner's seal is on the Adobe Approved Trust List, so Acrobat and Reader trust every signature automatically.
PAdES-sealed
The eSignature is embedded inside the PDF and tamper-evident — any change after signing is detectable.
Qualified timestamp
A trusted timestamp gives long-term validity (LTV), so the signature stays verifiable for years.
AATL is the global list of certificate providers that Adobe trusts.
A signature backed by AATL appears as valid in any Adobe reader and stands up in court.
eSignature API Frequently Asked Questions
Is the QuickSigner.com signature legally binding?
Yes. Signatures are sealed with our AATL certificate using the PAdES standard, with full legal weight under US ESIGN/UETA, UK and EU eIDAS for most business documents.
Do signers need an account?
No. Signers only need a secure link and an email address — no account, app or token.
How much does it cost?
To use the API, you’ll need a Pro plan plus $0.30 per signed document.
What file types are supported?
PDF and Word documents
Where are the code examples?
In the full API reference on Stoplight: quicksigner.stoplight.io.
Start integrating today
Legally binding eSignatures via a simple REST API. Start free.
