E-Signature API for Developers and AI Agents

Send legally binding documents for signature in one API call. Pay $0.10 per envelope. No subscription.

One API call. Pay per document. No subscriptions, no seat licenses, no enterprise sales calls.

Read the Docs View API Reference

Works with Claude, GPT, and any MCP-compatible agent

Also available: cryptographic timestamps ($0.02/receipt) and unified audit trails (free). See all services →

How it works

1. Upload your PDF

Send your document with recipients and field placement details in one request.

2. Recipients sign

Recipients receive a signing email instantly and complete the document securely.

3. Track completion

Receive webhook notifications as each signer completes their step.

Built for machines that build things

A practical e-signature API with strong defaults, clear behavior, and full control for product teams and autonomous agents.

Sequential signing

Send to multiple recipients in order, or switch to parallel signing when speed matters.

MCP native

Works as a tool for Claude and any AI agent that supports MCP.

x402 payments

Agents can pay autonomously with crypto, no account required.

Cryptographic timestamps

Prove a hash existed at a moment. Dual-signed by FreeTSA (RFC 3161) and Verafirma ES256. Free verification forever. $0.02 per receipt. Learn more →

Unified audit trails

Query every Verafirma event for a subject via one endpoint. Cross-service, polymorphic, free. Learn more →

Webhook events

Get real-time status updates for document creation, opens, and completion.

Idempotency

Safe retries prevent duplicate contracts, even across network failures.

Sandbox mode

Test with realistic responses at no charge and no recipient emails.

Complete field control

Place signature, initials, date, text, checkbox, radio, and dropdown fields anywhere on any page. Sequential or parallel signing. Every open-source signing capability, accessible via one API.

Full open-source API passthrough

Verafirma exposes the complete API surface: every recipient role, field type, signing configuration, and document option.

Recipient roles

  • SIGNER
  • APPROVER
  • VIEWER
  • CC
  • ASSISTANT

Field types

  • SIGNATURE, INITIALS, DATE, NAME, EMAIL
  • TEXT, NUMBER, CHECKBOX, RADIO, DROPDOWN

Signing order options

  • PARALLEL
  • SEQUENTIAL

Document configuration options

  • Custom email subject and message
  • Redirect URL after signing
  • Recipient expiration dates
  • Multi-language support
  • Signature type controls
  • Recipient authentication controls

Pricing

E-signature envelope

$0.10

per envelope, charged on success

Cryptographic timestamp

$0.02

per receipt, charged on success

Audit trail

Free

unlimited reads

No monthly fee. No seat license. No minimums.

Crypto (x402)

Pay per call, no account needed, designed for autonomous AI agents.

Prepaid Balance

Top up funds with Stripe, issue API keys, and manage usage in the dashboard.

Comparison reflects envelope pricing only. Timestamp and Trail don't have direct incumbent equivalents at this price point.

Provider Per Envelope Subscription
DocuSign API $4.80 / envelope $600 / year minimum
Verafirma $0.10 / envelope No subscription

What counts as one envelope?

One PDF sent to one or more recipients for signing.

Is there a free tier?

Yes. Use test_mode: true to send unlimited test envelopes at no charge.

Do I need an account?

No. Pay with crypto and start instantly without signup.

What can I use timestamps for?

AI agent output provenance (timestamp the hash of an LLM's response to prove what was generated when), pre-signature contract integrity (timestamp before send to prove what was offered), document freshness claims (invoices, reports), and compliance evidence. Receipts are RFC 3161-backed and accepted in ESIGN Act, eIDAS, and most legal frameworks.

How do I verify a timestamp receipt later?

Either call GET /v1/timestamp/verify/:id (free, returns full verification block) or verify the JWS locally against the public key at /.well-known/verafirma-timestamp-key.pem. No account or API key needed for verification — receipts are verifiable forever.

Legally binding in 180+ countries

Verafirma signatures comply with electronic signature laws worldwide. Every envelope includes a full audit trail: signer identity, timestamp, IP address, and device, meeting evidentiary requirements across frameworks.

United States

ESIGN Act (2000) - legal validity for e-signatures in interstate commerce.

UETA - adopted by 49 states, equal legal weight to handwritten signatures.

European Union

eIDAS - EU Regulation 910/2014. Produces SES-compliant signatures.

United Kingdom

Electronic Communications Act 2000 - recognizes e-signatures as binding.

Canada

PIPEDA - supports electronic document and signature validity.

Switzerland

ZertES - Swiss federal electronic signature compliance framework.

Electronic signature requirements vary by jurisdiction and document type. Consult qualified legal counsel for your specific use case. This does not constitute legal advice.

Trust signals

Audit trail

Complete records on every document event.

ESIGN aligned

Legally binding signatures with evidence suitable for compliance workflows.

Secure retention

Choose document retention windows that match your policy and risk model.

Open-source foundation

Built on the best of open-source e-sign infrastructure.

Contracts shouldn't cost more than the paper they replaced.