JustFill × n8n
Fill existing PDF forms from any n8n workflow.
Start with Excel, Google Sheets, CRM records, a database, or a webhook. JustFill handles the PDF geometry and returns a filled document; n8n controls everything before and after it.
The boundary is deliberate
Your source
Sheets, CRM, webhook, database
JustFill MCP
Detect, map, fill, reuse template
Your destination
Drive, approval, email, downstream API
JustFill does not send emails, submit forms, or update third-party systems on its own. That keeps each external side effect visible and configurable in your n8n workflow.
Setup
A production workflow in four steps.
Validate the form once with visible previews. For repeat production, save the reviewed layout so future runs use exact field geometry instead of rediscovery.
Step 1
Connect the hosted MCP endpoint
Use https://justfill.app/api/mcp in an MCP Client Tool node and authenticate with a JustFill API key.
Step 2
Normalize the incoming record
Select the fields you intend to place in the document. Do not pass an entire CRM record when the PDF needs only a subset.
Step 3
Open, inspect, and fill the PDF
Use open_pdf, map values to returned field ids, and call fill_pdf. Preview when a mapping is ambiguous.
Step 4
Save the reviewed template
Give fields semantic names and save the layout. The same unchanged form can then be filled deterministically.
AI-assisted first run
Useful when the form is new or field labels need interpretation. Keep preview and approval in the loop until the layout is reviewed.
Deterministic repeat runs
Best for recurring business forms. A saved template bypasses field detection and makes the mapping stable as long as the PDF itself is unchanged.
Frequently asked questions
Does the workflow require an AI agent?
No. For a recurring PDF, save the reviewed layout as a template and call the JustFill MCP tools in a deterministic n8n workflow. An AI Agent node is optional.
Can n8n use Excel, Google Sheets, a CRM, or a webhook as input?
Yes. n8n prepares the values from any upstream node. JustFill receives the PDF and the final field-value mapping, then returns a filled PDF link.
Does JustFill email or submit the PDF automatically?
No. JustFill returns the filled PDF. Your n8n workflow decides whether to store it, email it, request approval, or pass it to another system.
What happens when the PDF layout changes?
The saved template is tied to the exact document content. Open and review the changed PDF once, then save a new template before resuming automated fills.