A real e-signature API — included, not metered.
Wire signing into your own app with a clean REST API and webhooks. The twist: it's part of the $3/month Pro plan, not a per-envelope meter or a five-figure enterprise add-on. Build as much as you want on a flat price.
The API tax nobody talks about
Here's the part of e-signature pricing that catches builders off guard: the app might look affordable, but the moment you want to send documents from your own software, the meter changes. API envelopes are commonly billed individually — somewhere in the neighborhood of $1.25 to $4.80 each — or the API is locked behind an enterprise plan that can run into the hundreds or even thousands of dollars a month. Automate a workflow and watch the bill scale right along with your success.
We think that's backwards. The API isn't a luxury tier; it's just another way to do the thing you're already paying for. So at sign.pink the API is included on the $3 Pro plan — no per-envelope surcharge, no enterprise gate. Whether you send one document a month from the app or ten thousand from your backend, the price is the same flat $3.
Simple enough to ship today
It's a straightforward REST API: authenticate with a key, post a document, place fields, add signers, and send. Webhooks tell your app the moment something happens, so you're never polling for status. And every document you send programmatically carries the same tamper-evident audit trail as one sent by hand.
What the API gives you
Clean REST endpoints
Create documents, place fields, add signers, and send — all with predictable JSON over HTTPS. If you've used a REST API, you already know this one.
Webhooks for events
Get a callback the moment a document is sent, opened, signed, or completed, so your app reacts in real time instead of polling.
Simple API keys
Generate a key, send the header, you're authenticated. No OAuth ceremony required just to fire off a signing request.
Templates over the wire
Trigger a saved template programmatically, fill the variable fields, and send — perfect for sending the same document at scale.
API pricing, side by side
The app price is only half the story. Here's what happens when you want to send from your own code.
| sign.pink | DocuSign | Dropbox Sign | PandaDoc | |
|---|---|---|---|---|
| API included in base plan | ||||
| Per-envelope API fee | $0 | ~$1.25–$4.80 | Metered | Metered |
| Separate enterprise API plan | ||||
| Webhooks | ||||
| Same audit trail as the app | ||||
| Flat monthly price with API | $3/mo | Hundreds–thousands/mo | Add-on | Per-seat + API |
Competitor figures are illustrative of API/enterprise pricing as of June 2026 and often require annual billing or custom quotes. Verify current pricing before purchase.
No usage cliff
Because there's no per-envelope meter, scaling your automation doesn't quietly turn $3 into a four-figure invoice.
Same features, programmatic
Signing order, templates, and the audit trail all work through the API exactly as they do in the app.
API FAQ
No. The e-signature API is included on the $3/month Pro plan. There are no per-envelope API charges and no separate enterprise API tier to graduate into. The price you see is the price with the API.
Build on a real e-signature API — for $3/month, included.
No credit card to start. No envelope limits. No surprises.