Use the iTextMaster REST API to programmatically generate invoices and process PDFs. All API calls are authenticated with API keys and include free-tier access.
Overview
Use this page as the central API reference for authentication, endpoint patterns, Credits, response headers, and operational rules. For workflow-specific examples and FAQ, open the dedicated tool API pages from the menu.
Authenticated requests
Send x-api-key from server-side code.
Credits billing
1 successful basic PDF API call = 1 Credit.
Tool pages
Each priority API has its own examples and limits.
Get started with the iTextMaster API in two steps.
Sign in to your account, go to the Account page, and create an API key in the API Access section. Each account can have one active key at a time.
Use cURL, fetch, or any HTTP client to call the invoice generation endpoint.
curl -X POST https://itextmaster.com/api/external/invoice-generator/pdf \
-H 'Content-Type: application/json' \
-H 'x-api-key: YOUR_API_KEY' \
-d '{
"invoiceNumber": "INV-001",
"from": {
"name": "Your Company",
"email": "you@example.com",
"addressLines": ["123 Main St", "City, Country"]
},
"billTo": {
"name": "Client Name",
"email": "client@example.com",
"addressLines": ["456 Oak Ave", "City, Country"]
},
"items": [
{
"description": "Consulting Services",
"quantity": 10,
"rate": 150
}
]
}' \
--output invoice.pdfDeveloper entry points
Use these dedicated pages for workflow-specific examples, limits, error codes, and FAQ.
All API requests require an API key passed via the x-api-key header. Keys are prefixed with itm_live_ and are only shown once at creation time.
x-api-key: itm_live_your_api_key_hereSecurity note: Never expose your API key in client-side code or public repositories. Use environment variables and server-side proxies.
/api/external/invoice-generator/pdfGenerate a PDF invoice from a JSON payload. Returns the rendered PDF file directly.
Invoice Generator API landing page| Header | Required | Description |
|---|---|---|
x-api-key | Yes | Your API key (itm_live_...) |
Content-Type | Yes | application/json |
{
"invoiceNumber": "INV-001", // required
"from": { // required
"name": "Your Company",
"email": "you@example.com",
"phone": "+1-555-0100",
"addressLines": ["123 Main St"],
"taxId": "US12345678"
},
"billTo": { // required
"name": "Client Name",
"email": "client@example.com",
"addressLines": ["456 Oak Ave"]
},
"items": [ // required, at least 1
{
"description": "Consulting",
"quantity": 10,
"rate": 150
}
],
"currency": "USD", // optional, default USD
"taxRate": 0.1, // optional, e.g. 0.1 = 10%
"notes": "Payment due in 30 days", // optional
"dueDate": "2026-05-12", // optional
"issueDate": "2026-04-12" // optional
}/api/external/pdf-tools/:toolIdRun first-stage pdf-lib based operations through the API. Each successful API request costs 1 Credit. Failed processing attempts are refunded.
Credits
1 basic PDF API call = 1 Credit
Output
PDF for single-file results, ZIP for multi-file split results
Balance headers
Read X-Credits-Charged and X-Credit-Balance
| Name | Required | Description |
|---|---|---|
x-api-key | Yes | Your account API key. |
Content-Type | Yes | Use application/json or multipart/form-data. |
Use this format when your app already has base64 PDF bytes.
curl -X POST https://itextmaster.com/api/external/pdf-tools/merge-pdf \
-H 'Content-Type: application/json' \
-H 'x-api-key: YOUR_API_KEY' \
-d '{
"files": [
{ "name": "a.pdf", "dataBase64": "JVBERi0xLjcK..." },
{ "name": "b.pdf", "dataBase64": "JVBERi0xLjcK..." }
],
"options": {}
}' \
--output merged.pdfUse file for one PDF and repeated files fields for tools that accept multiple PDFs.
curl -X POST https://itextmaster.com/api/external/pdf-tools/split-pdf \
-H 'x-api-key: YOUR_API_KEY' \
-F 'file=@input.pdf;type=application/pdf' \
-F 'options={"mode":"ranges","ranges":[{"start":1,"end":2},{"start":3,"end":5}]}' \
--output split-results.zip| toolId | Files | Example options |
|---|---|---|
| merge-pdf | 2+ PDFs | {} |
| split-pdf | 1 PDF | {"mode":"ranges","ranges":[{"start":1,"end":3},{"start":4,"end":8}]} |
| rotate-pdf | 1 PDF | {"angle":90,"pages":[1,3,5]} |
| delete-pages | 1 PDF | {"pages":[2,4]} |
| extract-pages | 1 PDF | {"pages":[1,2,5]} |
| organize-pdf | 1 PDF | {"pageOrder":[3,1,2,4]} |
| edit-metadata | 1 PDF | {"title":"Report","author":"iTextMaster","subject":"Q2","keywords":"pdf,api"} |
| remove-metadata | 1 PDF | {} |
| page-numbers | 1 PDF | {"position":"bottom-center","format":"page-of-total","startNumber":1,"fontSize":12} |
| add-watermark | 1 PDF | {"type":"text","text":"CONFIDENTIAL","position":"diagonal","opacity":0.25,"fontSize":48} |
| header-footer | 1 PDF | {"header":{"center":"{date}"},"footer":{"right":"Page {page} of {total}"},"pageRange":"all"} |
| flatten-pdf | 1 PDF | {} |
| form-filler | 1 PDF | {"fields":{"Name":"Ada Lovelace","Approved":true},"flatten":true} |
add-blank-page | 1 PDF | {"position":"end","pageSize":"A4"} |
| reverse-pages | 1 PDF | {} |
| crop-pdf | 1 PDF | {"cropBox":{"x":36,"y":36,"width":540,"height":720},"pages":"all"} |
remove-annotations | 1 PDF | {} |
Credit unit
1,000 Credits = $1
Every signed-in user also receives 100 free API Credits each month.
Basic PDF API
1 Credit / call
Only API calls consume Credits. Browser-local website tools do not consume Credits; server-side website tools may apply fair-use limits.
Operational guide
Sign in to create an API Key, use your 100 monthly free API Credits, and buy additional Credits only when automation volume grows.