DocFast API Documentation

Convert HTML, Markdown, and URLs to PDF. Built-in invoice & receipt templates.

Base URL: https://docfast.dev

Authentication

All conversion and template endpoints require an API key. Pass it in the Authorization header:

Authorization: Bearer df_free_your_api_key_here

Get a free API key instantly — no credit card required:

curl -X POST https://docfast.dev/v1/signup/free \
  -H "Content-Type: application/json" \
  -d '{"email": "you@example.com"}'

Free tier: 100 PDFs/month. Pro ($9/mo): 10,000 PDFs/month. Upgrade anytime at docfast.dev.

Convert HTML to PDF

POST /v1/convert/html

Convert raw HTML (with optional CSS) to a PDF document.

Request Body

Field	Type	Description
`html` required	string	HTML content to convert
`css`	string	Additional CSS to inject
`format`	string	Page size: `A4` (default), `Letter`, `Legal`, `A3`
`landscape`	boolean	Landscape orientation (default: false)
`margin`	object	`{top, right, bottom, left}` in CSS units (default: 20mm each)

Example

curl -X POST https://docfast.dev/v1/convert/html \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "html": "<h1>Hello World</h1><p>Generated by DocFast.</p>",
    "css": "h1 { color: navy; }",
    "format": "A4"
  }' \
  -o output.pdf

Response

200 OK — Returns the PDF as application/pdf binary stream.

200 PDF generated 400 Missing html field 401 Invalid/missing API key 429 Rate limited

Convert Markdown to PDF

POST /v1/convert/markdown

Convert Markdown to a styled PDF with syntax highlighting for code blocks.

Request Body

Field	Type	Description
`markdown` required	string	Markdown content
`css`	string	Additional CSS to inject
`format`	string	Page size (default: A4)
`landscape`	boolean	Landscape orientation
`margin`	object	Custom margins

Example

curl -X POST https://docfast.dev/v1/convert/markdown \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "markdown": "# Monthly Report\n\n## Summary\n\nRevenue increased by **15%** this quarter.\n\n| Metric | Value |\n|--------|-------|\n| Users  | 1,234 |\n| MRR    | $5,670 |"
  }' \
  -o report.pdf

Response

200 OK — Returns application/pdf.

200 PDF generated 400 Missing markdown field 401 Invalid/missing API key

Convert URL to PDF

POST /v1/convert/url

Navigate to a URL and convert the rendered page to PDF. Supports JavaScript-rendered pages.

Request Body

Field	Type	Description
`url` required	string	URL to convert (must start with http:// or https://)
`waitUntil`	string	`load` (default), `domcontentloaded`, `networkidle0`, `networkidle2`
`format`	string	Page size (default: A4)
`landscape`	boolean	Landscape orientation
`margin`	object	Custom margins

Example

curl -X POST https://docfast.dev/v1/convert/url \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://example.com",
    "waitUntil": "networkidle0",
    "format": "Letter"
  }' \
  -o page.pdf

Response

200 OK — Returns application/pdf.

200 PDF generated 400 Missing or invalid URL 401 Invalid/missing API key

List Templates

GET /v1/templates

List all available document templates with their field definitions.

Example

curl https://docfast.dev/v1/templates \
  -H "Authorization: Bearer YOUR_KEY"

Response

{
  "templates": [
    {
      "id": "invoice",
      "name": "Invoice",
      "description": "Professional invoice with line items, taxes, and payment details",
      "fields": [
        {"name": "invoiceNumber", "type": "string", "required": true},
        {"name": "date", "type": "string", "required": true},
        {"name": "from", "type": "object", "required": true, "description": "Sender: {name, address?, email?, phone?, vatId?}"},
        {"name": "to", "type": "object", "required": true, "description": "Recipient: {name, address?, email?, vatId?}"},
        {"name": "items", "type": "array", "required": true, "description": "Line items: [{description, quantity, unitPrice, taxRate?}]"},
        {"name": "currency", "type": "string", "required": false},
        {"name": "notes", "type": "string", "required": false},
        {"name": "paymentDetails", "type": "string", "required": false}
      ]
    },
    {
      "id": "receipt",
      "name": "Receipt",
      "description": "Simple receipt for payments received",
      "fields": [ ... ]
    }
  ]
}

Render Template

POST /v1/templates/:id/render

Render a template with your data and get a PDF. No HTML needed — just pass structured data.

Path Parameters

Param	Description
`:id`	Template ID (`invoice` or `receipt`)

Request Body

Field	Type	Description
`data` required	object	Template data (see field definitions from `/v1/templates`)

Invoice Example

curl -X POST https://docfast.dev/v1/templates/invoice/render \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "data": {
      "invoiceNumber": "INV-2026-001",
      "date": "2026-02-14",
      "dueDate": "2026-03-14",
      "from": {
        "name": "Acme Corp",
        "address": "123 Main St, Vienna",
        "email": "billing@acme.com",
        "vatId": "ATU12345678"
      },
      "to": {
        "name": "Client Inc",
        "address": "456 Oak Ave, Berlin",
        "email": "accounts@client.com"
      },
      "items": [
        {"description": "Web Development", "quantity": 40, "unitPrice": 95, "taxRate": 20},
        {"description": "Hosting (monthly)", "quantity": 1, "unitPrice": 29}
      ],
      "currency": "€",
      "notes": "Payment due within 30 days.",
      "paymentDetails": "IBAN: AT12 3456 7890 1234 5678"
    }
  }' \
  -o invoice.pdf

Response

200 OK — Returns application/pdf.

200 PDF generated 400 Missing data field 404 Template not found 401 Invalid/missing API key

Sign Up (Get API Key)

POST /v1/signup/free

Get a free API key instantly. No authentication required.

Request Body

Field	Type	Description
`email` required	string	Your email address

Example

curl -X POST https://docfast.dev/v1/signup/free \
  -H "Content-Type: application/json" \
  -d '{"email": "dev@example.com"}'

Response

{
  "message": "Welcome to DocFast! 🚀",
  "apiKey": "df_free_abc123...",
  "tier": "free",
  "limit": "100 PDFs/month",
  "docs": "https://docfast.dev/#endpoints"
}

Save your API key immediately — it won't be shown again.

Error Handling

All errors return JSON with an error field:

{
  "error": "Missing 'html' field"
}

Status Codes

Code	Meaning
`200`	Success — PDF returned as binary stream
`400`	Bad request — missing or invalid parameters
`401`	Unauthorized — missing or invalid API key
`404`	Not found — invalid endpoint or template ID
`429`	Rate limited — too many requests (100/min)
`500`	Server error — PDF generation failed

Common Mistakes

# ❌ Missing Authorization header
curl -X POST https://docfast.dev/v1/convert/html \
  -d '{"html": "test"}'
# → {"error": "Missing API key. Use: Authorization: Bearer <key>"}

# ❌ Wrong Content-Type
curl -X POST https://docfast.dev/v1/convert/html \
  -H "Authorization: Bearer YOUR_KEY" \
  -d '{"html": "test"}'
# → Make sure to include -H "Content-Type: application/json"

# ✅ Correct request
curl -X POST https://docfast.dev/v1/convert/html \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"html": "<h1>Hello</h1>"}' \
  -o output.pdf