Generate Personalised Invitations and Merge Them Into One PDF in Power Automate: A 7-Step Dropbox Workflow

The painful part of bulk mailouts is not writing the letter, it is stitching the personalised copies together so finance, HR, or operations get one clean PDF instead of fifty attachments. This walkthrough builds the exact pattern in Power Automate with PDF4me Generate Documents (Multiple), Merge multiple PDF files, Dropbox, and a single Apply to each loop. Seven flow actions. One DOCX template. A JSON array of recipients. Out the other end falls one consolidated PDF, one page per recipient, named and uploaded back to Dropbox automatically.

Why-Based Q&A​

What You'll Get​

Input: One DOCX template with <<[merge_token]>> placeholders in /blog data/merge blog template/template.docx, plus a JSON array of recipients pasted into the Generate Documents (Multiple) action. Output: A single PDF named Merged_files.pdf uploaded to /blog data/merge blog template/output, with one personalised page per recipient in the same order as the JSON array. The template stays untouched in its source folder so re-runs are idempotent.

What You Need​

The Flow at a Glance​

1. Manually trigger a flow (trigger).
2. Dropbox: Get file content using path. Reads template.docx from Dropbox.
3. PDF4me: Generate Documents (Multiple). Template plus JSON array of recipients in, array of personalised PDFs out.
4. Initialize variable named mergefiles (Array).
5. Apply to each on body/outputDocuments, with Append to array variable using base64ToBinary(...) inside.
6. PDF4me: Merge multiple PDF files into a single PDF file. Array of binaries in, one PDF out.
7. Dropbox: Create file. Writes Merged_files.pdf back to Dropbox.

Complete flow overview​

Seven actions. Each card shows a green tick when configured. PDF4me sits in the middle twice: once to generate, once to merge.

Step 0: The DOCX Template​

Before any flow runs, the template needs the right merge tokens. Each <<[FieldName]>> placeholder is replaced once per recipient. Spelling and casing must match the JSON keys exactly.

Template preview​

The DOCX uses double-angle-bracket syntax. No special characters, no XML, just literal placeholders the PDF4me engine reads directly.

Step 1: Manually Trigger a Flow​

Flow so far: trigger only.

1. In Power Automate click Create, choose Instant cloud flow.
2. Pick Manually trigger a flow as the trigger.
3. Give the flow a name (e.g. Bulk Invitation Mailout) and click Create.
4. Leave the trigger inputs blank for now. Real production triggers (HTTP request, SharePoint list update, schedule) plug in here once the rest of the flow is working.

Step 2: Dropbox: Get File Content Using Path​

Flow so far: trigger plus Get file content.

Reads the template DOCX into the flow as raw bytes so Generate Documents can consume it directly.

1. Click + New step, search Dropbox, pick Get file content using path.
2. Connect Dropbox if you have not already.
3. Configure:
   • File Path: /blog data/merge blog template/template.docx
   • Infer Content Type: Yes
4. Save the flow and run a quick test. The action returns a File Content token containing the template binary.

Get file content configuration​

Infer Content Type Yes is what makes downstream PDF4me actions accept the file as a real DOCX, not as a generic stream.

Step 3: PDF4me: Generate Documents (Multiple)​

Flow so far: trigger plus Get file content plus Generate Documents (Multiple).

This is where one DOCX plus a JSON array becomes N personalised PDFs in a single action call.

1. Click + New step, search PDF4me, pick Generate Documents (Multiple).
2. Connect PDF4me Connect with your API key (first time only).
3. Configure the top half of the action:
   • Template File Type: Docx
   • Template File Name: Test.docx (label only, not a path)
   • Template File Data: pick the File Content token from step 2
   • Document Data Type: Json

Step 3a: Top of the action​

4. Paste the JSON array into Document Data Text. The walkthrough uses two recipients (John Doe, X AB). Each object has the same 19 keys, every key matches a <<[Token]>> in the DOCX template.

Step 3b: The JSON payload​

[
  {
    "DebtorNumber": "100001",
    "Salutation": "Mr",
    "Title": "Dr.",
    "FirstName": "John",
    "LastName": "Doe",
    "CareOfAddress": "c/o Accounting Department",
    "Address": "123 Main Street",
    "POBox": "PO Box 123",
    "PostalCode": "10001",
    "City": "New York",
    "Country": "United States",
    "HC_Name": "ABC Business Association",
    "SalutationText": "Dear Dr. Doe",
    "HC_Email": "[email protected]",
    "HC_Phone": "+1-212-555-0100",
    "HC_WoM_RegistrationDeadline": "2026-05-22",
    "HC_Street": "500 Park Avenue",
    "HC_PostalCodeCity": "10022 New York",
    "HC_WoM_Date": "2026-05-29",
    "HC_WoM_Time": "10:00"
  },
  {
    "DebtorNumber": "100001",
    "Salutation": "Mr",
    "Title": "Dr.",
    "FirstName": "X",
    "LastName": "AB",
    "CareOfAddress": "c/o Accounting Department",
    "Address": "123 Main Street",
    "POBox": "PO Box 123",
    "PostalCode": "10001",
    "City": "New York",
    "Country": "United States",
    "HC_Name": "ABC Business Association",
    "SalutationText": "Dear Dr. Doe",
    "HC_Email": "[email protected]",
    "HC_Phone": "+1-212-555-0100",
    "HC_WoM_RegistrationDeadline": "2026-05-22",
    "HC_Street": "500 Park Avenue",
    "HC_PostalCodeCity": "10022 New York",
    "HC_WoM_Date": "2026-05-29",
    "HC_WoM_Time": "10:00"
  }
]

5. Configure the bottom half:
   • Field Metadata: leave blank (optional, for currency, date, or number formatting)
   • Output Type: PDF
   • Keep Pdf template Editable: No

Step 3c: Output type​

6. Save and Test. The action returns body/outputDocuments, an array of objects, one per recipient. Each object carries a streamFile property containing the personalised PDF as a base64 string.

Step 4: Initialize Variable mergefiles​

Flow so far: trigger plus Get file content plus Generate Documents (Multiple) plus Initialize variable.

The merge action wants a collection of binaries. Create an empty array to hold them.

1. Click + New step, pick Initialize variable.
2. Configure:
   • Name: mergefiles
   • Type: Array
   • Value: leave blank

Initialize variable configuration​

Initialize variable always comes before the first Apply to each that needs it. Power Automate enforces this at design time.

Step 5: Apply to Each Plus Append to Array Variable​

Flow so far: trigger plus Get file content plus Generate Documents (Multiple) plus Initialize variable plus Apply to each.

Loop over the PDFs and convert each one to a binary buffer.

Step 5a: Apply to each (pick the source)​

1. Click + New step, pick Apply to each.
2. Configure:
   • Select an output from previous steps: pick body/outputDocuments from the Generate Documents (Multiple) action

Step 5b: Append to array variable (inside the loop)​

3. Inside the Apply to each container click Add an action, pick Append to array variable.
4. Configure:
   • Name: mergefiles
   • Value (expression, click fx): base64ToBinary(items('Apply_to_each')?['streamFile'])

Step 6: PDF4me: Merge Multiple PDF Files Into a Single PDF File​

Flow so far: trigger plus Get file content plus Generate Documents (Multiple) plus Initialize variable plus Apply to each plus Merge multiple PDFs.

Now the whole array goes in and one PDF comes out.

1. Below the Apply to each loop click + New step, search PDF4me, pick Merge multiple PDF files into a single PDF file.
2. Configure:
   • Body/docContent: pick the mergefiles variable token
   • Output File Name: Test.pdf

Merge action configuration​

3. The action concatenates the PDFs in array order, which is the JSON order. If your downstream consumer expects a specific sort (alphabetical, by debtor number, by region), sort the JSON before step 3 and the rest of the flow preserves that order.

Step 7: Dropbox: Create File​

Flow so far: trigger plus Get file content plus Generate Documents (Multiple) plus Initialize variable plus Apply to each plus Merge multiple PDFs plus Create file.

Write the merged PDF back to Dropbox.

1. Click + New step, pick Dropbox, Create file.
2. Configure:
   • Folder Path: /blog data/merge blog template/output
   • File Name: Merged_files.pdf
   • File Content: pick the File Content token from step 6 (Merge multiple PDFs)
3. Save the flow.

Create file configuration​

Run the Flow and Verify​

1. Click Test at the top right, choose Manually, click Test, then Run flow.
2. The flow execution panel turns green action by action. Generate Documents (Multiple) typically takes one second per record on a single-page template. Merge multiple PDFs adds another second or two for two recipients.
3. Open Dropbox at /blog data/merge blog template/output/. The file Merged_files.pdf is there.

The output, side by side​

Common Variations You Can Add Without Rebuilding​

Troubleshooting​

Next Steps​

The same seven-step pattern (trigger then fetch template then generate batch then loop-to-array then merge then save) works for any bulk personalised mailout in Power Automate. Ship one and the next ones cost almost nothing.