Go from API key to verified receipt with no package install.

JavaScript client

Works in modern runtimes that provide the Fetch API. The API key property is non-enumerable, and the client does not persist or log it.

Download leadproof.mjs →

curl -O https://leadproof.jessesay.chatgpt.site/sdk/leadproof.mjs

import { LeadProofClient } from "./leadproof.mjs";

const client = new LeadProofClient(process.env.LEADPROOF_API_KEY);
const receipt = await client.deliver({
  idempotencyKey: "form-submission-123",
  destination: "https://your-crm.example/webhook",
  name: "Sample Lead",
  email: "lead@example.invalid",
  source: "website_form"
});

Python client

Uses only json and urllib from the Python 3 standard library. No package registry or dependency installation is required.

Download leadproof.py →

curl -O https://leadproof.jessesay.chatgpt.site/sdk/leadproof.py

import os
from leadproof import LeadProofClient

client = LeadProofClient(os.environ["LEADPROOF_API_KEY"])
receipt = client.deliver(
    idempotency_key="form-submission-123",
    destination="https://your-crm.example/webhook",
    name="Sample Lead",
    email="lead@example.invalid",
    source="website_form",
)

Safe defaults

Fingerprint-verified replay

After a final failure, call client.replay(...) with the original idempotency key, identical payload, and identical destination. The clients add X-LeadProof-Replay: true; the API verifies the stored fingerprints before retrying.