How much does Inkly's e-signature API cost?

The API is included with Pro and Teams. Pro is $15 a month with 250 API documents a month, and Teams is $40 a month with 1,000. There are no per-document fees, and documents you send from Inkly itself stay unlimited.

What happens when I reach my monthly allowance?

New API sends are refused until the 1st of the next month, UTC, so you are never charged overage. Reading documents, signing links, reminders, and webhooks keep working, and moving from Pro to Teams raises the allowance straight away. Documents you send from Inkly itself stay unlimited and never count.

Is there a sandbox or test mode?

Not yet. Every document sent through the API is real and counts toward your allowance, so test by sending documents to your own email address and void anything you do not want to finish.

Which programming languages can I use?

Any language that can make an HTTPS request. It is a REST API with JSON bodies, and every endpoint in the docs has a copyable example in curl, JavaScript (including TypeScript), Python, PHP, Ruby, Go, Java, and C#. There is also an OpenAPI 3.1 document you can generate a client from or give to an AI coding agent.

Can signers sign inside my software?

You can skip Inkly's invitation email and get each signer's signing link instead, then send people to it from your own software, chat, or text message. Signing happens on Inkly's secure signing page, and nobody needs an Inkly account.

Can I send PDFs my own system generates?

Yes. Upload the PDF and place each field by its position on the page, or write text markers such as {{signature;signer=client}} into the document and let Inkly place the fields where it finds them. Every field type works, including signatures, initials, dates, text, numbers, checkboxes, and dropdowns.

How do I know when a document is signed?

Add a webhook endpoint and Inkly sends your server an event when a document is sent, viewed, signed, declined, completed, or voided. Each webhook is signed so you can verify it came from Inkly, and failed deliveries are retried.

Are documents signed through the API legally binding?

Yes, the same as any Inkly document. Electronic signatures are recognized under the ESIGN Act and UETA in the US and eIDAS in the EU, and each completed document comes with a Certificate of Completion recording who signed, when, and from which IP address, which you can download through the API.

Who can create API keys?

The workspace's primary owner and, on Teams, its admins. Each key is either Read, for checking documents, or Read and send, which can also send, remind, and void.

How does Inkly compare with SignWell or DocuSign on price?

SignWell's API costs $313 a month for 475 documents, and DocuSign's Advanced API plan costs $480 a month for 100 envelopes. Inkly Teams includes 1,000 for $40 a month, and Pro includes 250 for $15. Prices are from each company's published pricing, checked 3 November 2026.

The simplest e-signature API, at a fraction of the price.

Send documents for signature from your software with one request. When everyone has signed, the signed PDF and Certificate of Completion land back in it.

Start free Get an API key

Pro: 250 API documents a month for $15
Teams: 1,000 API documents a month for $40
No per-document fees

1. Your software sends one request

POST /api/v1/documents

{
  "template_id": "a2d94c10-…",
  "external_id": "crm-8841",
  "recipients": [{
    "role_id": "c81e7f42-…",
    "name": "Alex Morgan",
    "email": "alex@example.com"
  }]
}

2. Your signer signs on any device

Consulting agreement

From Northwind Studio

Client signature

Alex Morgan

Finish

No account or app needed

3. Your server hears back

document.sent10:02:14
Sent to Alex Morgan
recipient.viewed10:09:51
Alex Morgan opened it
recipient.signed10:11:03
Alex Morgan signed
document.completed10:11:05
Signed PDF and certificate ready

signed-agreement.pdf

completion-certificate.pdf

Skip building e-signatures yourself.

Collecting a legally binding signature means a signing page that works on every phone, invitation and reminder emails, a sealed PDF, and an audit trail that holds up. Inkly already runs all of it. Your code sends one request and listens for a webhook.

No signing page to build
No email delivery to run
No audit trail to design

Building it yourself

Render the PDF
Capture signatures
Email and remind
Seal the PDF
Keep an audit trail

Months of work before the first contract, and a legal record to get right.

Inkly API

One request
A webhook
The signed PDF

Inkly handles the signing page, emails, reminders, and Certificate of Completion.

From API key to signed PDF in three steps.

Step 1
Create an API key
Open API settings, create a Read and send key, and keep it on your server with your other secrets.
Authentication
Step 2
Send a document
One request sends a template or your own PDF, with an Idempotency-Key so a retry never sends twice.
Send from a template
Step 3
Get the signed PDF
Inkly calls your webhook the moment the last signer finishes. Your server then fetches the signed PDF with one request.
Webhooks

Your first request, in your language

curl -X POST "https://www.inkly.so/api/v1/documents" \
  -H "Authorization: Bearer $INKLY_API_KEY" \
  -H "Idempotency-Key: crm-8841-send-1" \
  -H "Content-Type: application/json" \
  -d '{
    "template_id": "a2d94c10-6e7b-4f38-8c15-1f3e9b7d6c02",
    "title": "Consulting agreement",
    "external_id": "crm-8841",
    "recipients": [
      {
        "role_id": "c81e7f42-0b39-4d6a-a7c4-92e15d3f8b76",
        "name": "Alex Morgan",
        "email": "alex@example.com",
        "delivery": "email"
      }
    ],
    "cc": [
      {
        "name": "Sam Lee",
        "email": "sam@example.com"
      }
    ],
    "prefilled_values": {
      "Project name": "Website redesign"
    },
    "message": "Please sign by Friday."
  }'

Prefer a walkthrough? Start with the API docs, or read the step-by-step help guide.

Three ways to put fields on the page.

From a template

Set the document up once in Inkly's editor. Each send only names who fills each role, with values like a price prefilled from your records.

Send from a template

Your PDF, by position

Upload any PDF and place each field as a fraction of the page. Works for scans and documents you cannot edit.

Send a PDF

Your PDF, with markers

Write a marker where each field goes, hide it in white, and Inkly places the field there. It moves with your text.

Send a PDF with markers

What developers build with it.

Each one is a request or two, with a guide that walks through it.

Send contracts when a deal closes

CRMs, sales tools, and agencies

When a deal is marked won, send your contract template with the client's name and price filled in, and tag it with your own record ID so every webhook finds its way back.

POST /api/v1/documents

{
  "template_id": "a2d94c10-6e7b-4f38-8c15-1f3e9b7d6c02",
  "external_id": "crm-8841",
  "recipients": [
    {
      "role_id": "c81e7f42-0b39-4d6a-a7c4-92e15d3f8b76",
      "name": "Alex Morgan",
      "email": "alex@example.com"
    }
  ],
  "prefilled_values": {
    "Project name": "Website redesign",
    "Monthly fee": "$4,500"
  },
  "automatic_reminders": true
}

Sign the PDFs your system generates

Quoting, invoicing, and order systems

Your system already makes the quote or order form. Write markers into it where each field goes, upload the PDF, and send it with markers turned on. No measuring.

POST /api/v1/documents/from-upload

{
  "upload_id": "d06b8e24-9f13-4c7a-a5d8-3e1c7f2b6049",
  "use_markers": true,
  "recipients": [
    {
      "ref": "client",
      "name": "Alex Morgan",
      "email": "alex@example.com"
    },
    {
      "ref": "agency",
      "name": "Jordan Park",
      "email": "jordan@agency.example"
    }
  ]
}

Collect signatures inside your software

Onboarding flows, portals, and marketplaces

Skip Inkly's invitation email and get each signer's link in the response, then send people to sign from your own software, chat, or text message.

POST /api/v1/documents

{
  "template_id": "a2d94c10-6e7b-4f38-8c15-1f3e9b7d6c02",
  "recipients": [
    {
      "role_id": "c81e7f42-0b39-4d6a-a7c4-92e15d3f8b76",
      "name": "Alex Morgan",
      "email": "alex@example.com",
      "delivery": "link"
    }
  ]
}

Store the signed PDF with the record

Back offices, HR systems, and document archives

When the document.completed webhook arrives, ask for a download link and save the signed PDF and its Certificate of Completion next to the customer or employee it belongs to.

GET /api/v1/documents/{id}/signed-pdf

{
  "url": "https://files.example.com/signed/consulting-agreement.pdf?token=…",
  "expires_at": "2026-11-02T15:09:05.123Z",
  "file_name": "Consulting agreement.pdf"
}

Follow up without opening Inkly

Ops dashboards and internal tools

List documents and their status in your own dashboard, nudge a signer who has gone quiet, or void a document that went out with the wrong terms.

POST /api/v1/documents/{id}/remind

// No body. Emails everyone who still has to sign by email.

{
  "sent_count": 1,
  "skipped_count": 0,
  "failed_count": 0
}

Let an AI agent write the integration

Teams building with coding agents

Point your agent at the OpenAPI document and the docs guide, and it has every endpoint, field, and error code it needs. Tell it to send only to your own email while testing.

Prompt for your coding agent

Read https://www.inkly.so/api/v1/openapi.json
and https://www.inkly.so/llms.txt, then add an
Inkly send to our deal-won handler. Send
only to my own email while testing.

Your software hears about every signature as it happens.

Six events. Sent, viewed, signed, declined, completed, and voided, each carrying your own external_id.
Signed and verifiable. Check each webhook with any Standard Webhooks library, or copy the Node.js and Python verifiers.
Retried until you answer. A delivery that fails is tried again, and each webhook has an ID so you can skip duplicates.
Ready to copy. The docs include a complete endpoint in Express and Flask, and API settings can send a test event.

document.sent10:02:14
Sent to Alex Morgan
recipient.viewed10:09:51
Alex Morgan opened it
recipient.signed10:11:03
Alex Morgan signed

document.completed10:11:05

Signed PDF and certificate ready

{
  "type": "document.completed",
  "document": {
    "id": "3f1c2a7e-…",
    "status": "completed",
    "external_id": "crm-8841"
  }
}

An e-signature API without per-envelope pricing.

Most e-signature APIs charge by the document, so the bill grows with every contract. SignWell's API costs $313 a month for 475 documents, and DocuSign's Advanced API plan costs $480 a month for 100.

Inkly Teams includes 1,000 API documents a month for $40: more than twice the documents SignWell gives you for less than 1/7 of the price, with unlimited team members and everything else in the plan. Just starting out? Pro includes 250 API documents for $15 a month.

Documents you send from Inkly itself stay unlimited and never count toward the allowance. If you reach it, sends pause until the 1st instead of running up a bill.

Inkly Teams

$40

a month for 1,000 documents

SignWell

$313

a month for 475 documents

DocuSign

$480

a month for 100 documents

Monthly price and included API documents for e-signature APIs
Plan	Includes
Inkly Teams$40 a month1,000 API documents a month, no per-document fees	1,000 API documents a month, no per-document fees
Inkly Pro$15 a month250 API documents a month, no per-document fees	250 API documents a month, no per-document fees
SignWell API$313 a month475 documents a month	475 documents a month
DocuSign API Advanced$480 a month100 envelopes a month	100 envelopes a month

The API comes with everything else in Pro and Teams.

Templates, reminders, signing order, custom branding, and the rest of each plan come with your API documents. Sending from Inkly itself stays unlimited on every plan.

2 months free with annual billing

Free

For individuals

Not included:
Not included:
Not included:
Not included:
Not included:
Not included:
Not included:

Start free

No credit card required

Pro

For professionals and small businesses

/month

Pay $180 todaySave $48 a year

Start with Pro

Teams

For growing teams

/month

Pay $480 todaySave $108 a year

Start with Teams

See full pricing

Built for production, not just the demo.

Everything you need to build it.

Guides for each way to send, a page for every endpoint with examples in eight languages, and a help guide for setting up keys and webhooks in your account.

https://www.inkly.so/api/v1

Full API reference

Account

get/meGet the current key

Templates

Sending

Documents

Files

OpenAPI

get/openapi.jsonGet this API description

Questions about the API.

Pricing, limits, testing, and what you can build.

Read the API docs →

Free to start. No credit card required.

Send your first document
from your own software.

Create a key, send one request, and get the signed PDF back when everyone has signed.