Developer Documentation

Build with Kwill

APIs, webhooks, and guides for clients, projects, invoices, and proposals — all in one place.

kwill-api.ts

GETList Clients
const response = await fetch(
  'https://usekwill.com/api/v1/clients',
  { headers: { Authorization: `Bearer ${apiKey}` } }
);
const clients = await response.json();
200 OKResponse
[
  { "id": "cl_4f9a...", "name": "Acme Corp",
    "email": "acme@example.com" },
  ...
]

POSTCreate Invoice
const res = await fetch(
  'https://usekwill.com/api/v1/invoices',
  { method: "POST",
    headers: { Authorization: `Bearer ${key}`,
      'Content-Type': 'application/json' },
    body: JSON.stringify({
      client_name: "Acme Corp",
      client_email: "acme@example.com",
      line_items: [{ description: "Design",
        quantity: 1, rate: 2500 }],
      total: 2500,
      due_date: "2026-12-01" }) })
200 OKResponse
{
  "id": "inv_7b2c...",
  "status": "draft",
  "total": 2500,
  "due_date": "2026-12-01"
}

POSTCreate Webhook
const res = await fetch(
  'https://usekwill.com/api/v1/webhooks',
  { method: "POST",
    headers: { Authorization: `Bearer ${key}`,
      'Content-Type': 'application/json' },
    body: JSON.stringify({
      url: "https://example.com/hook",
      event_types: ["invoice.paid"]
    }) })
200 OKResponse
{
  "id": "wh_3a1f...",
  "url": "https://example.com/hook",
  "event_types": ["invoice.paid"]
}

⚡Quick StartMake your first API call in under 5 minutes.📖API ReferenceFull reference for all 15 REST endpoints.🔔WebhooksReal-time events for invoices, proposals, and more.🔑AuthenticationAPI key management, roles, and best practices.📚Core ConceptsPagination, rate limits, errors, and idempotency.🛠️GuidesStep-by-step recipes for common integrations.