Nex-SignNex-Sign
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E-signatures as a Web API

Drop signing into your product with one API call.

Send a Word document with placeholder tokens. Nex-Sign converts it, emails each signer a secure magic link, captures the signature, and returns a sealed, tamper-evident PDF — then notifies your webhook. You pay per signed document, nothing else.

Start free — 20 documents See the API

No card required · 20 documents or 7 days, whichever comes first · Data in AWS London

Client signature
Try it — draw your signature
Sealed · SHA-256
HMAC-signed webhooks SHA-256 sealed PDFs AWS London storage Full audit trail
What it does

How does the Nex-Sign e-signature API work?

Nex-Sign turns a single API call into a complete signing pipeline: it converts your DOCX to PDF, emails each signer a magic link, captures the signature, and returns a signed DOCX plus a SHA-256 sealed PDF. There is no signing UI to build and no coordinates to compute.

  1. 01

    You POST a DOCX

    Send your Word template with placeholder tokens ($signature, $date) and the signer list. One authenticated request.

  2. 02

    We convert & place fields

    We render the document, locate your tokens (split-run safe) and drop signature/date fields exactly where they belong.

  3. 03

    Signers get a magic link

    Each recipient is emailed a secure, branded link to a hosted signing page — type, draw, or upload. No account required.

  4. 04

    You get a sealed record

    A signed DOCX plus a tamper-evident, SHA-256 sealed PDF — delivered to your webhook and stored to download.

What you get

What does the Nex-Sign e-signature API include?

One Nex-Sign API call covers conversion, delivery, signature capture, sealing and webhooks. Every document is stored in AWS London (eu-west-2) and produces a tamper-evident sealed PDF with a full audit trail.

One endpoint

A single POST creates, converts, emails, seals and notifies. No SDK to learn, no per-envelope surprises.

DOCX-native

Keep authoring in Word. We sign on your real template — no rebuilding documents as web forms.

Sealed legal record

Every completed document produces a SHA-256 sealed PDF: the tamper-evident source of truth, with a full audit trail.

Signed webhooks

HMAC-SHA256 signed events, retried up to 24 hours until you return 200. Your app always stays in sync.

UK data residency

All documents stored in AWS London (eu-west-2). Retention-first handling for records you must keep.

Your branding

Brand the signing invite per business — your intro copy, button label and colour — from the dashboard or API.

Signing flows

Can one document be sent to several signers?

Yes. Nex-Sign supports any number of signers on a document, notified either all at once (parallel) or one after another in a set order (sequential).

Parallel or sequential

Email everyone at once, or route in order — each signer is notified only after the previous one signs. Any number of signers.

Collision-proof placement

Anchor fields on a keyword or a Word bookmark. Bookmarks are structural, so they can never clash with the document's own text.

Track every step

Events like recipient.signed, recipient.bounced, envelope.declined and envelope.completed keep your app in sync in real time.

Chasing signatures

Does Nex-Sign remind signers who haven't signed?

Yes. Nex-Sign sends one automatic reminder to any signer who still hasn't signed 24 hours after their invite, and you can send a reminder yourself at any time with POST /v1/envelopes/:id/remind or one click in the dashboard. Reminders are worded as reminders, never as a duplicate invite, and both kinds emit a recipient.reminded webhook.

One automatic nudge

Sent 24 hours after the invite, once per signer — never twice. It is cancelled automatically if they sign, if the email bounces, if the envelope closes, or if you chase them yourself first.

Remind on demand

One authenticated call re-sends to everyone on the envelope who hasn't signed, with a fresh magic link. Signers who already signed are skipped — you never have to work out who to chase.

Never spams your signer

A per-signer cooldown plus per-document and per-account caps mean a retry loop or an over-eager user can't bury someone in email. Over the limit returns 429 with a Retry-After.

Pricing

How much does an e-signature API cost?

Nex-Sign charges prepaid document credits, not a subscription: Lite is $75 for 100 documents ($0.75 each) and Pro starts at $250 for 500 documents ($0.50 each). Credits stay valid for 12 months as one shared balance across every business in your account. The free trial covers 20 documents or 7 days, whichever comes first, with no card.

Lite

$75one pack

100 documents · $0.75 / document

  • Fixed entry pack
  • Full API, hosted signing & webhooks
  • Sealed PDF + audit trail on every doc
  • Credits valid 12 months
Start with Lite
Best value

Pro

from $250scalable

500+ documents · $0.50 / document

  • Everything in Lite
  • Choose your volume — scale up any time
  • Lowest per-document rate
  • Low-balance email alerts
Start with Pro

Around 1,200–1,500 documents a month? Pro lands at $0.50/doc, and any credits you don't use stay valid for a full year.

One endpoint

How do I send a document for signature via API?

Authenticate with a Bearer token and POST a DOCX plus a small JSON payload to /v1/envelopes. Nex-Sign replies 202 Accepted, then runs conversion, delivery, signing and sealing for you.

  • Signature & date fields, placed by keyword
  • Idempotency keys & your own external_id
  • Short-lived signed download URLs
Get your API token Read the docs 
curl -X POST https://nex-sign.com/v1/envelopes \
  -H "Authorization: Bearer <YOUR_TOKEN>" \
  -F "files=@agreement.docx" \
  -F 'payload={
    "subject": "Please sign",
    "recipients": [{ "email": "signer@acme.com", "fullName": "A. Signer" }],
    "fields": [{ "documentName": "agreement.docx",
      "recipientEmail": "signer@acme.com",
      "type": "signature", "anchorKeyword": "$signature" }]
  }'
Webhooks

How do e-signature webhooks work?

Nex-Sign POSTs a JSON event to your endpoint at each step of the signing process, signed with X-NexSign-Signature (HMAC-SHA256) and retried for up to 24 hours until your endpoint returns 200. Pick an event to see its payload.

A single recipient completed their signature.

{
  "event": "recipient.signed",
  "envelope": { "id": "env_9fA2…", "status": "in_progress" },
  "recipient": { "email": "signer@acme.com", "status": "signed" },
  "occurredAt": "2026-07-14T10:07:44Z"
}

Start signing in minutes

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