Send it by text too. 25¢ per envelope.
Signing notifications via email, SMS, or both, in one API call. Tag a PDF, POST it, and your first envelope is out the door in minutes.
curl -X POST https://api.esigndev.com/v1/envelopes \
-H "Authorization: Bearer sig_live_..." \
-H "Idempotency-Key: order-41882-contract-1" \
-F "file=@agreement.pdf" \
-F 'payload={
"delivery": "both",
"signers": [{
"name": "Jane Smith",
"email": "jane@example.com",
"phone": "+18135551212"
}]
}'
You build the PDF and drop anchor tags where the fields go: ^S1 for the signature, ^D1 for the date. White text on a white background, so the tags are invisible to the reader and still sitting in the text layer where we can find them.
Post the file with your signer details. We deliver by email, SMS, or both in parallel, and fire a webhook when it's signed. Download the signed document there and keep your own copy.
No drag-and-drop field editor. No coordinate maps. No template system to learn. One endpoint and a PDF you already know how to generate. There's no sales call between you and a sent document, and the first send is minutes of work, not an afternoon.
You're billed when an envelope is created, not when it's signed. If your signer declines, ignores it, or you void it, it still cost 25 cents. We'd rather you read that here than discover it on an invoice.
If your signers are contractors, tenants, patients, field staff, or anyone who doesn't sit in an inbox all day, email delivery is the whole problem. The link that arrives by text gets opened.
| Per envelope | SMS delivery | Monthly fee |
|---|---|---|
| Siglio — 25¢ | Yes, included | None |
| The other 25¢ API | No | $25/mo |
| Open-source, self-hosted | No | You operate it |
| The incumbents | Yes | $50 to $480/mo |
Both channels fire in parallel to the same signer, not as a fallback after email bounces, and SMS isn't an add-on charge. It's in the 25 cents.
Two signers per envelope. PDF only, 15 MB, no encrypted files. Webhooks included on every account, one endpoint per environment, all event types. Bearer token auth, no JWT assembly and no consent screen.
Not with us. Signers get the completed, signed PDF by email or text, good for 90 days with reissue. You get the signed result on the completion webhook, and you should download it there and keep your own copy. Your archive is your archive.
Sign up with an email address and your sandbox key is on screen in under a minute. The first 25 envelopes are free, no card required. The request is one POST: a PDF, a signer, a delivery channel. Most developers send their first test document in the same sitting they signed up.
Businesses whose signers are consumers on phones, not counterparties at desks. Home services, enrollments, settlements, intake paperwork: agreements that die when signing feels like a chore. Siglio meets the signer where they already are, in their messages, and that is why documents come back signed.
Endpoints, the tag system, delivery options, the complete error table, idempotency semantics, webhook retry behavior, limits, and billing. All of it public, none of it behind a sales call.
Every endpoint has a cURL example. Every error in the reference is one your code can actually receive. And if something in there is unclear or missing, tell support, because that's how the docs get better.
Sign up with an email, no card. Your sandbox envelopes deliver to real inboxes and real phones, so the first thing you test is the real thing. When you're ready to go live, add a card and keep the same integration.
Stuck on something? Ask through the contact form and a real question gets a real answer from someone who knows the product, usually the same day.
Start building free