n8n-nodes-pdf-form-filler

An n8n community node that fills AcroForm PDF fields with JSON data from your workflow.

Features

• Discover Fields — extract all form field names, types, options, and current values from any AcroForm PDF
• Fill Form — write values into text fields, checkboxes, radio groups, and dropdowns
• Static or dynamic mapping — define field mappings in the node UI or pass them as JSON at runtime
• Date formatting — automatic ISO date conversion with configurable format tokens (DD/MM/YYYY, etc.)
• Dot-notation data keys — access nested JSON values like applicant.address.postcode
• Warnings and observability — execution hints in the n8n UI, structured server-side logging

Installation

Self-hosted n8n

Install via the n8n GUI:

1. Go to Settings → Community Nodes
2. Enter n8n-nodes-pdf-form-filler
3. Click Install

Or install via the command line:

cd ~/.n8n
npm install n8n-nodes-pdf-form-filler

Restart n8n after installation. The node appears in the node panel as PDF Form Filler.

n8n Cloud

Not yet available on n8n Cloud. See docs/deployment.md for details.

Quick Start

1. Discover your PDF's fields

Create a workflow: Read Binary File → PDF Form Filler (Discover Fields)

The output JSON contains an array of all fields with their exact names, types, and available options.

2. Build your mapping

Each mapping entry connects a key in your JSON data to a field in the PDF:

{ "dataKey": "firstName", "pdfField": "A1-First name" }

Field names must match exactly (case-sensitive, whitespace-sensitive). Use the Discover Fields output to get the correct names.

3. Fill the form

Create a workflow: Read Binary File → Set Data → PDF Form Filler (Fill Form)

The node reads the PDF binary and your JSON data from the same input item, applies the mapping, and outputs a filled PDF binary.

Operations

Discover Fields

Returns metadata for every form field in the PDF.

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | PDF Binary Property | string | data | Binary property containing the PDF |

Output: JSON with fields array and fieldCount. Each field has name, type, options, currentValue, and readOnly.

Fill Form

Fills PDF form fields with data from the input item.

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | PDF Binary Property | string | data | Binary property containing the PDF | | Mapping Source | options | static | static (UI) or dynamic (from input JSON) | | Field Mappings | fixedCollection | — | Mapping entries when using static mode | | Dynamic Mapping Property | string | fieldMappings | JSON property name when using dynamic mode | | Output Binary Property | string | data | Binary property name for the filled PDF | | Output File Name | string | filled-form.pdf | Filename for the output PDF | | Warn on Missing Values | boolean | true | Emit warnings for mapped fields with no data | | Default Date Format | string | DD/MM/YYYY | Format for ISO date strings |

Output: JSON summary (status, fieldsFilled, fieldsMissing, fieldsSkipped, fieldsErrored, warnings) plus the filled PDF as binary.

Supported Field Types

| PDF Field Type | Input Value | Example | |---------------|-------------|---------| | Text | string | "John Smith" | | Checkbox | boolean | true / false | | Radio Group | string (exact option) | "Three" | | Dropdown | string (exact option) | "Single" |

Date Formatting

ISO date strings (e.g. 2026-06-01) are automatically formatted using the configured date format. Supported tokens:

| Token | Output | Example | |-------|--------|---------| | DD | Day, zero-padded | 01 | | D | Day, no padding | 1 | | MM | Month, zero-padded | 06 | | M | Month, no padding | 6 | | YYYY | 4-digit year | 2026 | | YY | 2-digit year | 26 |

Set a per-field format with dateFormat on the mapping entry, or use Default Date Format for all fields.

Documentation

• User Guide — detailed usage instructions
• Field Mapping Guide — how to create and configure mappings
• Deployment Guide — installation, upgrading, requirements
• Operations Guide — troubleshooting, error reference, logging

Development

# Install dependencies
npm install

# Build
npm run build

# Run tests (156 tests)
npm test

# Run tests with coverage
npm test -- --coverage

# Lint
npm run lint

# Generate filled PDFs for manual verification
npm run test:manual

Local n8n testing

See docs/operations/local_testing.md for instructions on linking the node to a local n8n instance.

Architecture

Three-layer design: Node → Engine → Adapter

n8n Node Layer        — UI, binary I/O, n8n lifecycle
Engine Layer          — mapping resolution, type coercion, orchestration (pure TS, no n8n imports)
pdf-lib Adapter       — PDF load/save, field introspection, value writing

License

MIT