eSignature API
REST eSign API. AATL-certified electronic signatures, PAdES-sealed, ISO 27001 secure. Webhook on completion.
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eSignature API
Legally Binding
Add legally binding electronic signatures to your app with a simple REST eSign API. Your users never leave your product.
Our electronic signature is AATL-certified, PAdES-sealed, ISO 27001 secure.
Start building with a FREE developer account — production from just a Pro Plan + $0.30 per document.
What Is An eSignature API?
An eSignature API is a programmatic interface that lets your application send documents for electronic signature, manage signers and signing workflows, and retrieve the completed document — without users ever leaving your product.
You upload a file and add signers; the API returns a signed, tamper-evident PDF, sealed with an AATL certificate and backed by 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 by email — no account needed.
Get the signed PDF
When everyone has signed, you receive the sealed, AATL-certified PDF and its audit trail.
Embedded eSigning — Your App, Your Brand
Your users never leave your product.
Create the sign request, take the signUrl we return for each recipient, and load it in an iframe inside your own interface. Same AATL-certified, PAdES-sealed document at the end — your UI around it.
Three parameters do the work: hideInfoPanel strips our panel for a clean fit, signedRedirectUrl returns signers to your app, disable_notifs stops us emailing people who are already looking at your screen.
No redirects
Signers stay on your domain. No new tab, no branded interstitial, no drop-off.
Your styling
hideInfoPanel removes our chrome so the signing view sits inside your layout.
Webhook on completion
signedRedirectUrl handles the thank-you screen. REQUEST_COMPLETED tells your backend the sealed PDF is ready.
eSign API: From Zero to eSigned in Two Requests
Upload the file, then send it for e-signature. That’s it. Your app never handles certificates, sealing, or signer notifications — the eSignature API takes care of all of it and hands back a signed PDF. Webhook on completion.
# 1. Upload the document
curl -X POST https://app.quicksigner.com/api/v1/files \
-H "Authorization: YOUR_API_KEY" \
-F "file=@contract.pdf"
# → { "fileName": "a1b2c3d4-...-contract.pdf" }
# 2. Send it for signature
curl -X POST https://app.quicksigner.com/api/v1/requests \
-H "Authorization: YOUR_API_KEY" \
-d '{ "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 }] }] }'
# → Jane gets a secure signing link. You get a webhook on completion.Two calls. That's the whole integration. Authentication is a single API key in the Authorization header — no OAuth dance.
Sealed Documents Are Adobe Verified (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 e-Signatures
QuickSigner's seal is on the Adobe Approved Trust List, so Acrobat and Reader trust every electronic signature automatically.
PAdES sealed documents
The electronic signature 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
An electronic signature backed by AATL appears as valid in any Adobe reader and stands up in court.
eSignature API: Frequently Asked Questions
What really matters in choosing an eSignature API?
Most eSignature APIs look similar on the pricing page. The differences show up later — when an auditor asks whether your signatures still validate, when your usage doubles and the per-envelope model stops making sense, or when you try to move providers and discover your audit trails won’t come with you. The seven factors below are the ones that tend to matter most once a signature workflow is actually running in production.
- Cryptographic standard: PAdES (with LTV timestamping) ensures PDFs remain verifiable for years.
- Security & compliance: ISO certifications and cloud/TSA qualified timestamps verify trust.
- Legal framework: eIDAS, ESIGN/UETA, GDPR—make sure your provider meets your region’s regulatory needs.
- Pricing model: Envelope‑based ($/doc) vs. user‑based ($/seat)—audit your usage patterns.
- Integration features: Templates, bulk sending, webhooks, OAuth/SSO support, mobile, attachments.
- Vendor lock‑in & export: Can you easily migrate documents & audit trails?
- Signer experience & court‑readiness: Audit logs, metadata, and certificate-based signatures reduce legal disputes.
Why developers choose QuickSigner eSignature API?
QuickSigner is built for teams that need real cryptographic and legal compliance without enterprise pricing attached to it.
- Best for cost-efficient volume: At $0.30 per document, QuickSigner is among the most affordable while delivering top-tier compliance.
- Enterprise-grade security: ISO‑27001 & PAdES ensure enterprise-grade security, legal safety across jurisdictions.
- Adobe-ready PDF workflows: Compatible with industry-standard PDF readers and verification tools.
- Flexible billing: Choose per-use or per-user plan—scales from startups to mid-size businesses.
Is the QuickSigner electronic 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.
Why PAdES, ISO & Adobe Verified matter for an eSignature API?
Together these three standards cover the full chain of trust: how the eSignature is embedded, how the provider is run, and whether the rest of the world will recognise the result.
- PAdES compliance embeds closed, cryptographically secured signatures in PDFs. QuickSigner, for example, fully supports it.
- ISO/IEC 27001‑certified services (e.g. QuickSigner) follow rigorous security management standards.
- Adobe Verified platforms ensure maximum compatibility with PDF readers, plus trusted, asset‑backed verification and Qualified Timestamps for “long-term validity”
Does the QuickSigner eSignature API support webhooks?
Yes. Register an endpoint and QuickSigner POSTs an event whenever a document is viewed, signed, completed, or expires — no polling needed. Full payload reference is in the API docs.
How do I authenticate?
With a single API key sent in the Authorization header. Get it from the API page of your account after enabling API access — no OAuth setup required.
Do signers need an account?
No. Signers only need a secure link and an email address — no account, app or token.
Can I try the QuickSigner eSign API for free?
Yes. Sign up for a free developer account and enable the API on your My Account page — you can create unlimited sign requests for testing. Completed documents are watermarked on the free plan; upgrade to Pro for production use + $0.30 per document.
How much does QuickSigner eSignature API cost for production?
To use the electronic signature API, you’ll need a Pro plan plus $0.30 per signed document.
What file types are supported?
PDF and Word files are supported.
Where are the code examples for the eSign API?
You can find the code examples in the full QuickSigner eSignature API reference on Stoplight: quicksigner.stoplight.io and github.com/QuickSignerCom/esign-api
Where do I get the eSign API key?
Sign up for a free account at quicksigner.com — the free developer account lets you test the API with unlimited sign requests. Go to My Account and enable the API. Your API key will appear on the API page in your account.
Send it in the Authorization header with every request. Full API reference with a “Try it” console: quicksigner.stoplight.io
Send templates and agreements for eSignature — in two API calls
Legally binding eSignatures. Start free. Test free. No credit card.
