Merge PDF Overlay in Make

Merge Overlay is a Make module by PDF4me that stamps one PDF layer on top of a base PDF, applying the same watermark, header, or template across every page. Use it for batch branding, legal notices, and stamps. The module takes a base document and a layer document, then returns the combined PDF ready to send.

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Authenticating Your API Request

To access the PDF4me Web API through Make, every request must include proper authentication credentials. Authentication ensures secure communication and validates your identity as an authorized user, enabling seamless integration between your Make scenarios and PDF4me's overlay merging services.

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Important Facts You Should Not Miss

The layer draws on top of the base

Base Document is the PDF you keep. Layer Document is the overlay that sits on top of every page. Use a transparent background on the layer so the base content stays visible beneath the stamp.

Both files are binary buffers

Base Document and Layer Document each need the raw PDF content from a prior download module Data field. Map each from its own source step rather than passing a file path or URL.

One layer, consistent branding

A single layer PDF stamps the same watermark or header across the whole base document, which keeps branding identical on every page without editing each one by hand.

Map Base File Name and Base Document from the source PDF, then map Layer File Name and Layer Document from the overlay PDF you want stamped on top.

What is Merge Overlay in Make?

Merge Overlay is Make's PDF4me module for compositing one PDF over another. It accepts a base PDF and a layer PDF, then returns a single document with the layer drawn on top of the base pages. Unlike stamping each file by hand, this module applies the same overlay across a batch of documents inside an automated scenario.

Parameters

Parameter	Required	What it does	Example
Connection	Required	PDF4me connection holding your API key. Click Add and paste your key from dev.pdf4me.com/dashboard if connecting for the first time.	My PDF4me connection
Base File Name	Required	Filename of the base PDF that receives the overlay, including the .pdf extension. Map it from the prior module output.	1. File Name
Base Document	Conditional	Binary content of the base PDF from a prior download module Data field. Required when Base File Name is provided.	1. Data
Layer File Name	Required	Filename of the overlay PDF, the watermark, header, or template that sits on top.	5. File Name
Layer Document	Conditional	Binary content of the overlay PDF from a prior download module Data field. Required when Layer File Name is provided.	5. Data

Output

Field	Type	What it contains
Name	String	Output filename for the overlaid PDF, derived from the Base File Name input. Use it in the destination upload module File Name field.
Doc Data	Buffer	Binary content of the merged PDF with the layer stamped on top. Map it into a cloud-storage upload module or an email attachment.

How does the Merge Overlay module work in Make?

The module reads both PDFs, then draws the layer document over the base document page by page and returns a single merged file. The layer is composited on top, so a transparent watermark shows the base content through it. This is the standard way to stamp branding onto a batch of PDFs. The PDF format itself is an open ISO standard, described on the Wikipedia PDF page. For scenario building patterns, see the Make help center.

Typical Setups

Stamp a letterhead onto invoices

1. Trigger on a new invoice PDF in cloud storage.
2. Download the invoice as the base and the letterhead PDF as the layer.
3. Run Merge Overlay to composite the letterhead onto every page.
4. Upload the branded invoice or email it.

Batch watermark PDFs

1. List PDFs in a folder and iterate them.
2. Use a one-page transparent watermark PDF as the Layer Document.
3. Merge Overlay stamps the watermark onto each base.
4. Save the results to a Watermarked folder.

Add a confidential banner

1. Download the report and a CONFIDENTIAL overlay PDF.
2. Composite them with Merge Overlay.
3. Send the stamped report to reviewers.

Practical Tips

Use transparency to show the base

An opaque layer hides the base content. Use a transparent-background layer PDF so the base shows through a watermark.

Base vs layer

The base is the document you keep. The layer is the overlay, drawn on top of the base pages.

Map both filename and data pairs

Provide Base File Name plus Base Document, and Layer File Name plus Layer Document, from their download steps.

The layer applies to every page

The overlay stamps onto all base pages, so make a one-page layer for a repeated mark.

Original is preserved

The module returns a new merged PDF and leaves the sources untouched. One credit per document.

Cheat Sheet

Field	Value
Module	PDF4me > Merge Overlay
Connection	Your PDF4me connection
Base File Name	1. File Name
Base Document	1. Data
Layer File Name	5. File Name
Layer Document	5. Data
Output	Doc Data (overlaid PDF)
Credits	1 per document

Common Questions

How do I overlay one PDF onto another in Make?+

Add the PDF4me Merge Overlay module, map the base PDF to Base File Name and Base Document, map the overlay PDF to Layer File Name and Layer Document, then run the scenario. The module stamps the layer over every page of the base document and returns the combined PDF on the Doc Data output.

How do I add a watermark to a PDF in Make?+

Create a one-page PDF that holds your watermark on a transparent background, then use it as the Layer Document. Merge Overlay composites the watermark onto each page of the base PDF, which is a quick way to batch-brand documents without editing each file. See the Make help center for mapping the layer from cloud storage.

What is the difference between the base document and the layer?+

The base document is the PDF you want to keep and stamp onto. The layer document is the overlay, such as a watermark, header, or template, that is drawn on top of the base pages. If the layer is opaque it will hide the base content, so use transparency where you want the base to show through.

How many credits does Merge Overlay use?+

The module uses one PDF4me credit per document. The PDF4me pricing page lists the current credit allocations for the free and paid tiers, so you can estimate the cost of a high-volume overlay scenario before you build it.

Related Actions

Merge 2 PDFs

Append one PDF after another when you need sequential pages rather than a stamped layer.

Merge Multiple PDFs

Combine several PDFs into a single file in one module call.

Split PDF

Break a document into separate files by page count or ranges before or after overlaying.

Same Task on Other Platforms

Overlay PDFs in n8n

Same layer stamp as an n8n node for self-hosted and code-first workflows.

Merge PDF Overlay in Zapier

Stamp a watermark or letterhead layer onto PDFs from any of 6,000+ Zapier apps.

Merge Overlay in Power Automate

Microsoft 365 flows across SharePoint, Outlook, and Teams.

Merge Overlay REST API

The raw endpoint for custom backend code, batch stamping, or server-side jobs.

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