Best PDF Watermark APIs in 2026: Adobe, pdfRest, Nutrient, iLoveAPI, ConvertAPI and ApyHub Compared

Updated 30 September 2026. Rewritten with current pricing, free tiers and features for every provider. PSPDFKit is now listed under its new name, Nutrient, and Adobe PDF Services and ConvertAPI have been added.

01Introduction

A PDF watermark API adds text or an image to the pages of a PDF through a single HTTP request, so your application can mark documents automatically instead of someone doing it by hand in a PDF editor. Teams use it to stamp "DRAFT" or "CONFIDENTIAL" on internal files, put a logo on reports and invoices, or label documents with a client name before they are shared.

This guide compares six watermark PDF APIs on the things that decide the choice in practice: what you can use as a watermark, how much control you get over placement and style, what the free tier covers, what paid use costs, and how large a file each one accepts. All figures were checked on each provider's own pages on 30 September 2026. Prices and limits change, so confirm them before you commit.

02Why teams use an API for PDF watermarks

Watermarking one PDF is easy in any desktop editor. Watermarking every invoice your app generates, or every contract a customer downloads, is a different job. An API lets you:

Mark documents at the moment they are created or downloaded, with no manual step
Apply the same text, logo and placement to every file
Watermark PDFs that live elsewhere by sending a URL instead of the file
Add the step to a larger document workflow, such as generate, watermark, then password-protect

A visible watermark labels and brands a document. It does not lock one. Anyone with a PDF editor can remove many watermarks, and at least one provider in this list sells a watermark removal endpoint. For documents that must stay closed, combine the watermark with encryption or access control.

03What makes a good PDF watermark API

Watermark types. Text, image, or a PDF page used as the watermark. Some APIs support all three; one supports only a PDF.
Placement and style controls. Opacity, rotation, position, font, size and color, plus whether the watermark sits above or behind the page content.
Page selection. Watermarking every page is the default. Watermarking selected pages or ranges needs explicit support.
Input options. Upload the file, send a public URL, or both. URL input saves bandwidth when the PDF already sits in cloud storage.
Free tier and cost per watermark. How many watermarks you can test for free, whether free output carries the provider's own watermark, and what each call costs at volume.
File size limits. Scanned contracts and image-heavy reports reach 50 to 100 MB quickly.

04The comparison

1. Adobe PDF Services API

Adobe's PDF Watermark API is part of the Adobe PDF Services suite. It uses the first page of a separate PDF as the watermark and places it on your document.

Where it shines

500 free document transactions per month with no credit card (pricing)
100 MB file size limit for all documents
Opacity, foreground or background placement, and page ranges
Official SDKs for Java, .NET, Node.js and Python

Where it lags

The watermark must be a PDF. Text and image watermarks are not supported directly, so you create a watermark PDF first
No public paid pricing; volume use goes through Adobe sales
Rotation and position controls are not documented

2. pdfRest

pdfRest's Watermark PDF API has the most detailed text controls in this list and an API Lab where you can test calls in the browser and copy the generated code.

Where it shines

Text or PDF watermarks with over 70 fonts, size, RGB or CMYK color, opacity, rotation, offsets and page ranges
Watermark can sit behind the page content
Premium plan from $9.99 a month for 600 calls (cloud API)
Self-hosted container and AWS options for teams that can't send files to a cloud API

Where it lags

Image watermarks need a separate conversion to PDF first
Free Starter plan is 100 calls a month, and its output carries a pdfRest watermark (pricing)
Paid plans include a set file size (5 MB on Premium) and charge $0.015 per extra MB

3. Nutrient (formerly PSPDFKit)

PSPDFKit rebranded as Nutrient in October 2024. Its PDF Watermark API runs on the Nutrient DWS Processor API and charges 1 credit per watermark.

Where it shines

Text or image watermarks with width, height, position, opacity, rotation, font, color and style
Sizes and positions accept percentages, which keeps placement consistent across page sizes
Official TypeScript and Python clients, plus a Postman collection and an MCP server

Where it lags

Free tier is 50 credits a month, and free output carries a Nutrient watermark (pricing)
Pay-as-you-go needs a card and a $25 wallet load; no named paid plan is listed below the custom tier
No file size limit is published

4. iLoveAPI (iLovePDF)

The developer API behind iLovePDF now runs as iLoveAPI. Its watermark tool has the widest set of layout options, including a mosaic mode.

Where it shines

Text or image watermarks with page ranges, nine-point positioning plus pixel offsets, opacity, rotation, font, color and above or below layering
Mosaic mode repeats the watermark nine times per page
2,500 free credits a month; a PDF watermark costs 10 credits, so about 250 watermarked PDFs a month (pricing)
SDKs for PHP, .NET, Ruby and Node.js

Where it lags

Image watermarks must be uploaded to iLoveAPI's servers before the call
Paid prices sit behind a calculator, so cost at volume takes some working out
No file size limit is published

5. ConvertAPI

ConvertAPI splits watermarking into separate endpoints for text, image and PDF overlays, and adds page variables such as page number and date.

Where it shines

Text watermarks with 12 fonts, size, color, stroke, opacity, rotation, alignment, offsets and page ranges
Variables such as %PAGE% and %DATE% for dynamic stamps
Paid plans from $10 a month for 1,000 conversions, with file limits from 200 MB (pricing)
SDKs in eight languages, including C#, Java, Python, Node.js and Go

Where it lags

The free allowance is a one-time trial of 250 conversions that expires after 30 days
Image watermarks follow the page's rotation rather than taking a free angle
Overage rates are not published on the pricing page

6. ApyHub

ApyHub's PDF Watermark API is the simplest option here. You send a PDF by upload or URL, add watermark text, a PNG logo or both, and get back the watermarked file or a link to it. It is one of the APIs in the ApyHub catalog, so the same key and subscription also cover related document work.

· bash

curl -X POST "https://api.eu.apyhub.com/apyhub/apply-watermark-on-pdf/url/url" \
  -H "apy-token: $APY_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "file_url": "https://assets.apyhub.com/samples/sample.pdf",
    "watermark_text": "DRAFT"
  }'

· json

{
  "url": "https://s3.amazonaws.com/bucket/watermarked.pdf"
}

Where it shines

Four endpoints covering upload or URL input, and file or link output
100 MB per request on every plan, including the free tier
100 atoms per call. Atoms are ApyHub's usage unit, and the Pro plan's 100,000 atoms a month for €15 covers about 1,000 watermarks (pricing)
One subscription covers the rest of the catalog, including converting images to PDF before you watermark them, and headers, footers and stamps
Every endpoint is available through ApyHub MCP, so AI agents in Claude, ChatGPT or Cursor can discover and call it without a hand-written wrapper or tool definition
Each service carries machine-readable certification covering data handling and alignment with GDPR, SOC 2 and ISO 27001, and runs in EU or US regions

Where it lags

No opacity, rotation, position or font controls; the text or PNG is applied to every page with default styling
No page range selection
Image watermarks must be PNG
The free Starter plan covers 3,000 atoms a month (about 30 watermarks) and 5 calls a day, the smallest free allowance in this list for watermarking

Try the PDF Watermark API free →

05Summary table

Provider	Watermark types	Style and placement controls	Page ranges	Free allowance	Paid entry point	Max file size
Adobe PDF Services	PDF only	Opacity, foreground or background	Yes	500 transactions/month	Contact sales	100 MB
pdfRest	Text, PDF	Font, size, color, opacity, rotation, offsets, behind page	Yes	100 calls/month (watermarked output)	$9.99/month for 600 calls	5 MB included, up to 250 MB on Premium
Nutrient	Text, image	Size, position (% or points), opacity, rotation, font, color	Not documented	50 credits/month (watermarked output)	Pay-as-you-go from a $25 wallet	Not published
iLoveAPI	Text, image	Position, offsets, opacity, rotation, font, color, mosaic, layer	Yes	2,500 credits/month (~250 PDFs)	Calculator on pricing page	Not published
ConvertAPI	Text, image, PDF	Font, size, color, stroke, opacity, rotation, alignment, offsets	Yes	250 conversions, one-time 30-day trial	$10/month for 1,000 conversions	200 MB and up
ApyHub	Text, PNG image	Default styling only	No	3,000 atoms/month (~30) and 5 calls/day	€15/month (~1,000 watermarks)	100 MB

06Which PDF watermark API should you choose?

It depends on what you are building.

You need precise branding control (exact fonts, colors, position, specific pages): pdfRest, iLoveAPI and ConvertAPI give the most options.
You want the largest free monthly allowance to test and run small workloads: Adobe PDF Services (500 transactions) and iLoveAPI (about 250 PDFs).
You already use Adobe's document stack and can prepare a watermark PDF: Adobe PDF Services fits alongside the rest of its APIs.
You need to self-host: pdfRest offers container and AWS deployments.
You want a plain "stamp DRAFT or a logo on every page" call, alongside other file and data APIs on one key, callable by AI agents: ApyHub keeps it to one request, with limited styling.

07Conclusion

Every API in this list can watermark a PDF from code. They differ in what they accept as a watermark, how much control you get over its look and placement, and how generous the free allowance is. For branded, positioned watermarks on selected pages, the options-heavy APIs are the better fit. For a fast, consistent mark on every page as one step in a wider workflow, a simpler API is enough.

If the watermark is one step in a larger flow, such as converting scans to PDF, stamping them and sending them on, the ApyHub catalog covers those steps with one key.

Explore the file manipulation APIs →

For watermarking other media, see our comparisons of image watermarking APIs and video watermarking APIs.

08FAQ

What is a PDF watermark API? A PDF watermark API adds text, an image or another PDF page on top of or behind the pages of a PDF through an HTTP request. Applications use it to mark documents automatically as they are created or downloaded.

Which PDF watermark API has the biggest free tier? Adobe PDF Services includes 500 document transactions a month, and iLoveAPI's 2,500 monthly credits cover about 250 watermarked PDFs. pdfRest and Nutrient have free tiers too, but their free output carries the provider's own watermark.

Can I use an image or logo as a PDF watermark? Nutrient, iLoveAPI, ConvertAPI and ApyHub accept images directly. pdfRest and Adobe need the image turned into a PDF first.

Can I watermark only some pages of a PDF? Yes, with Adobe, pdfRest, iLoveAPI and ConvertAPI, which support page numbers or ranges. ApyHub applies the watermark to every page.

Does a watermark protect a PDF from being copied? No. A visible watermark labels and brands a document, but PDF editors and some APIs can remove it. For documents that must stay private, add password protection or encryption as well.

Can an AI agent watermark PDFs? Yes, if the API is reachable through MCP. ApyHub's PDF Watermark API is available through ApyHub MCP, so an assistant like Claude or ChatGPT can watermark a file when you ask in plain words. Nutrient also offers an MCP server.

How can I test a PDF watermark API before integrating it? Most providers let you try calls in the browser: pdfRest has an API Lab, ConvertAPI has a live demo after sign-up, and every ApyHub API page has a "Try it" panel. You can also test from Voiden, a free, open-source API client that stores requests as Markdown files, or from curl.

How much does it cost to watermark 1,000 PDFs a month? On the published plans, about $10 with ConvertAPI (Developer plan, assuming one watermark counts as one conversion), €15 with ApyHub (Pro plan) and about $56 with pdfRest (Premium's 600 included calls plus 400 at $0.115 each). Adobe, Nutrient and iLoveAPI price volume through sales, a credit wallet or a calculator.

09Sources

Checked on 30 September 2026:

Adobe, PDF Watermark API documentation and pricing
pdfRest, Watermark PDF and pricing
Nutrient, PDF Watermark API, pricing and rebrand announcement
iLoveAPI, API reference and pricing
ConvertAPI, watermark APIs and pricing

This comparison is published by ApyHub, which is one of the providers listed. We have tried to describe every option fairly, including where our own API falls short.

10About ApyHub

ApyHub is a curated API catalog and trusted operational layer for developers and AI agents, with over 1,500 endpoints or capabilities and growing. Teams use the whole catalog through a single subscription priced in atoms, a unit that reflects the actual work each call performs. Every endpoint ships with machine-readable certification aligned with GDPR, SOC 2 and ISO 27001, and is MCP-ready by default, so AI agents can discover and call it through ApyHub MCP without custom wrappers. ApyHub is headquartered in Amsterdam, with offices in the Netherlands, Greece and India, and serves 65,000+ developer workspaces every month. The free tier requires no card. Building an API of your own? Become a provider →

Best PDF Watermark APIs in 2026: Adobe, pdfRest, Nutrient, iLoveAPI, ConvertAPI and ApyHub Compared