Pay-per-call eSignature for developers + AI agents.

Send a contract for signature in one HTTPS call. Pay $0.10 per envelope, no minimum, no commitment. AI-agent-friendly: x402 per-call payment, MCP discovery, OpenAPI 3.1, llms.txt.

The lodestone, in five lines Read the quickstart →

curl -X POST https://api.verafirma.com/v1/envelopes \
  -H "PAYMENT-SIGNATURE: $(cat payment.b64)" \
  -F 'pdf=@contract.pdf' \
  -F 'payload={"title":"NDA","recipients":[{"email":"x@example.com","name":"X","role":"SIGNER"}]}'

Pay per call

$0.10 per envelope. No minimum. No commitment. Use it once and never come back; never get billed for nothing.

No signup required

Sign an x402 payment authorization off-chain, send one HTTPS request, get a signing URL. The wallet IS the identity for any later history reads.

Agent-native

OpenAPI 3.1, MCP discovery, llms.txt, .md doc twins, audience-tagged surfaces. Built for programs, not just for humans clicking dashboards.

Pricing in one line

$0.10 per envelope. Pay per call — no minimum, no commitment. Refunded automatically on terminal failure (rejected, expired, cancelled) up to a per-envelope cap.

See the per-mode breakdown →

Discover the API

Quickstart — five-line curl from PDF + recipient + payment to signing URL.
The lodestone path — design rationale for the canonical agent use case.
x402 wire format — EIP-3009 per-call payment authorization.
MCP — point an MCP-compatible client at https://api.verafirma.com/mcp.
API reference — audience-augmented OpenAPI 3.1 surface.
llms.txt + llms-full.txt — agent-friendly discovery surfaces.