How to add e-signature to an app
Call an API to create the document, let the signer use a hosted page, listen for a webhook, and store the sealed file. You can do that in an afternoon. Don't build the signing page yourself, because the evidence is the hard part.
By docuinked. Published 2026-11-07, updated 2026-11-07.
Build or buy
Drawing a signature on a canvas takes an hour. The product is everything around it: consent, a log nobody can edit, a seal, delivery, and being able to explain it all in five years. Our view is that most apps should rent this and spend their time on what makes them different.
The five steps
1. Create. Your backend sends the PDF and signers. Keep the key on your server, never in browser code.
curl https://docuinked.com/v1/documents \
-H "Authorization: Bearer $DOCUINKED_API_KEY" \
-H "Idempotency-Key: order-1042" \
-H "Content-Type: application/json" \
-d '{"title": "Order 1042", "pdf_url": "https://example.com/1042.pdf",
"signers": [{"name": "Dana Reed", "email": "dana@example.com"}],
"metadata": {"order": "1042"}}'2. Place the fields. You have three ways. Tags such as {{signature:1}} in the PDF are the best for templates you control. Anchors find text such as Signature:. Coordinates are fractions of the page. If you give none, fields go on the document's own Signature, Date and Name lines; with no such lines, each signer gets a field on the last page.
3. Send. Call send_document. The signer gets an email with their own link. If you want signing inside your own app, your server can call create_signing_link for a sent document and show it to the right user. Treat that link like a password.
4. Listen. Add a webhook and verify the signature. Update your record on document.completed.
5. Store. Fetch the signed PDF and the evidence, and keep both. Don't count on any vendor, us included, being there in ten years.
Mistakes to avoid
- Retries with no idempotency key. This is how people get two contracts.
- Polling for status. Use webhooks.
- A shared link for several signers. Each signer needs their own, or your evidence means little.
- Blocking the signer's copy. Everyone needs to be able to keep the record.
- Calling your flow legally safe. Check your documents with a lawyer.
Test it first
Use a test key so no email goes out. sign@test.docuinked.com signs by itself, so your whole flow can run in a CI job.
Common questions
Can users sign inside my app without leaving it?
Your server can create a signing link and send the user to it. The page itself is ours and can't be framed, because the signing step has to be the same trusted page for everyone.
How long does an integration take?
The calls above are a small job. Plan more time for your own edge cases: declined documents, expired links and changed terms. Those are what take the time.
Do my users need a docuinked account?
No. Signers never need an account. Only the people who run your integration do.
Related
Try it in test mode
Free during the beta. Test keys send no email, so you can build the whole flow first.