A REST API designed to disappear into your product. Send documents, place fields, capture signatures, verify chains. The same audit trail that powers Vouch.ink, available to your users by default — at developer pricing.
# Send a document for signature
curl -X POST https://api.vouch.ink/v1/documents \
-H "Authorization: Bearer vk_live_a3f87f2a..." \
-H "Content-Type: application/json" \
-d '{
"title": "Service Agreement",
"file_url": "https://your-bucket/contract.pdf",
"recipients": [
{ "email": "sarah@example.com", "name": "Sarah Mitchell", "role": "Tenant", "order": 1 }
],
"expires_in_days": 7,
"auto_remind": true,
"webhook_url": "https://your-app.com/hooks/vouch"
}'
// → 201 Created
{
"id": "3f1c8a2b-6d0e-4b7a-9c21-5e8f0a7d4b19",
"audit_id": "00472",
"status": "sent",
"recipients": [
{ "name": "Sarah Mitchell", "order": 1, "status": "invited",
"sign_url": "https://vouch.ink/sign/a3f8..." }
],
"auto_remind": { "next_at": "2026-05-08T14:24:18Z", "sent": 0 },
"chain_root": "f1d2e8a4b9c0457e..."
}When something happens to a document — opened, signed, declined, sealed — Vouch posts a signed webhook to your endpoint. Same audit chain, delivered to your stack.
Every webhook contains the full event payload, the previous hash, this event's hash, and an HMAC signature you can verify against your shared secret.
If your endpoint returns anything other than 2xx, Vouch retries with exponential backoff up to 24 hours. After that, the event waits in your replay queue until you fetch it.
// Headers
// X-Vouch-Signature: t=1715028281,v1=a3f87f2a...
// X-Vouch-Event-Id: evt_9f3c2a1e8d4b
// Content-Type: application/json
{
"id": "evt_9f3c2a1e8d4b",
"type": "document.signed",
"created_at": "2026-05-06T14:24:18Z",
"document": {
"id": "3f1c8a2b-6d0e-4b7a-9c21-5e8f0a7d4b19",
"audit_id": "00472",
"title": "Service Agreement"
},
"signer": {
"email": "sarah@example.com",
"name": "Sarah Mitchell",
"ip": "72.182.144.21",
"user_agent": "Mozilla/5.0..."
},
"chain": {
"previous_hash": "2e7c1a4b8d0f3956...",
"this_hash": "a3f87f2a9c1ad440..."
}
}Anyone can verify a Vouch document's audit chain — no API key required, no Vouch login, no trust assumed. The math does the work.
curl https://api.vouch.ink/v1/verify/3f1c8a2b-6d0e-4b7a-9c21-5e8f0a7d4b19
// → 200 OK
{
"audit_id": "3f1c8a2b-6d0e-4b7a-9c21-5e8f0a7d4b19",
"status": "chain_intact",
"chain_spec": 2,
"canonicalization": "RFC 8785 (JCS)",
"hash_formula": "sha256(prev_hash|event_type|recipient_id|actor_email|ip|user_agent|canonical_payload|created_at)",
"event_count": 8,
"events": [
{
"sequence": 1,
"event_type": "document.created",
"created_at": "2026-05-06T09:31:12.193916+00:00",
"prev_hash": "GENESIS",
"this_hash": "f1d2e8a4b9c0457e...",
"payload": { "page_count": 3, "source_hash": "4023...582f" }
},
// ... 7 more events ...
],
"chain": { "valid": true, "broken_at": null, "count": 8 }
}The public verify endpoint returns every hash in the chain, without the personal data (signer emails, IP addresses) those hashes cover. The document's owner downloads the full chain with GET /v1/documents/{id}/audit and can re-compute every hash with any SHA-256 implementation, then compare the final hash with the public one.
Canonicalization uses RFC 8785 (JSON Canonicalization Scheme), which means deterministic hashes across implementations. API customers get reference verifiers in Node, Go, Python, Ruby and Rust, standard library only, with the rules written out so you can write your own.
Most e-signature APIs treat your customers as Vouch's customers. Ours treat them as yours. Your branding on emails, your domain on signing pages, your audit IDs in your records.
Your logo on emails. Your wordmark on signing pages. Your sender name in the inbox. Vouch's brand only appears in the small print, where compliance requires it.
Each of your customers gets their own audit chain. Their data never crosses tenant boundaries. Verifiable independence between accounts is a first-class feature, not a sales obstacle.
Aggregate usage across all your tenants on one Vouch invoice, or pass through per-tenant charges via the metering API. Whichever fits your pricing model.
The big e-signature providers put embedding for your own customers behind enterprise plans, custom quotes or add-ons. Vouch ships it on Business Premium, public price, sign up online.
| Provider | Lowest tier with API | Audit trail | Multi-tenant | Public verifier |
|---|---|---|---|---|
| DocuSign | Standard / $25/user/mo | Yes | Enterprise only | No |
| PandaDoc | Custom / sales call | Yes | Custom only | No |
| Adobe Acrobat Sign | Custom / annual | Yes | Enterprise only | No |
| Dropbox Sign | Premium / $40/user/mo | Yes | Limited | No |
| SignNow | Premium / $15/user/mo | Yes | Add-on | No |
| Vouch | Business Premium / $15/mo annual | SHA-256 chain | Yes, included | Yes, public |
Data verified May 2026. Prices and tiers may have changed since. Don't take our word for it — check theirs.
Sign up, generate a key, send your first document via API in under ten minutes. No sales call, no contract minimum, no annual commit.