wmk

Overview

wmk is a free, open-source Python tool for adding text or image watermarks through a command line, with an optional Python library interface. It suits people who can work with command-line tools and want a repeatable way to watermark batches on their own machine. Its format coverage and batch controls are useful; the Python 3.10 requirement and first-frame-only GIF handling narrow its fit.

Key features

Batch jobs can target folders recursively or use glob patterns, making wmk practical for repeatable image-delivery workflows. By default, results go into a watermarked directory while retaining the input folder structure. Existing destination files are protected unless overwrite is enabled; otherwise, wmk uses a “_watermarked” suffix to avoid collisions.

Watermarks can be text or logos, placed in any corner or at the center, with opacity set from 0 to 100. JPG, JPEG, PNG, WEBP, TIFF, BMP, and GIF are supported for input and output. The GIF caveat matters: only the first frame is processed, so this is not a suitable choice when preserving animation is required.

A dry-run option prints planned outputs without writing files, useful for checking a batch before committing it. The README describes processing as offline, keeping images on the user's machine. Installation is through pip, pipx, or a repository clone; the package requires Python 3.10 or newer. The CLI is the primary interface, with a Python library available as an option. A pytest suite and Ruff checks are project trust signals, not a substitute for assessing fit in a particular workflow.

Pricing

add-watermark — free. The MIT-licensed tool has no paid plans listed, so its watermarking features do not sit behind a subscription tier. The license permits use, copying, modification, distribution, sublicensing, and sale subject to its conditions. There is no free trial because the software is free. The trade-off is operational rather than financial: users need Python 3.10 or newer and must be comfortable using a command line.

Platforms

wmk is categorized for Linux, macOS, and Windows desktop use. The package metadata specifically names Windows and Linux as supported platforms. It is a local command-line tool, not a browser-based service.

Who it's for

wmk is a strong fit for photographers, product-image workflows, or other users who need repeatable batch watermarking and are comfortable installing and scripting Python software. Local processing will also appeal to people who prefer images to remain on their machine. Choose another tool if you need a graphical workflow, animated GIF support, or do not meet the Python requirement. Support is routed through the repository's GitHub Issues page.

Pros and cons

• Pros: Recursive folders, glob patterns, and preserved output structure make batch work easier to repeat and organize.
• Pros: Text and logo marks, five placement choices, and adjustable opacity cover core watermarking needs.
• Pros: Offline processing and a dry run offer useful control over image handling and output changes.
• Cons: The command-line-first approach and Python 3.10+ requirement make it a poor fit for users seeking a ready-to-use visual editor.
• Cons: GIF processing handles only the first frame, so animated files will not retain their full sequence.

Alternatives

For a broader platform range and a freemium option, consider Watermarkly: its free batch processing adds a Watermarkly logo, while 1-Year Access costs $19.95 a year and is billed annually without renewal. Terma is another free option across Linux, macOS, self-hosted, web, and Windows, though its stated focus is network services and software development rather than watermarking.

On Apple devices, PictStamp is a free alternative for iOS and macOS. eZy Watermark may suit users seeking watermark templates, 300+ fonts, export to other apps, and high-resolution downloads; its free plan is available, with Premium at $1.99 a month. Watermark.ws offers a free basic tier for one photo at a time, with 1 GB storage, slow processing, and no custom fonts, so it is a less direct match for large batches.

DoWatermark is worth considering for browser-based processing without uploads and saved presets; its free plan allows three images per batch and text or logo marks. Overlay Studio is a free Android, iOS, and web choice with a 25-image batch limit, raised by a supporter code. Watermark Maker targets Android and iOS users who want text and logo marks, tiling, and social export presets; its free tier uses small batches and ads, with a lifetime option at 24.99 USD. For a list of options, see Photo Watermarking Software.

Verdict

Choose wmk if you want free, local, scriptable batch watermarking and are comfortable with Python and the command line. Its practical folder handling, placement controls, and broad still-image format support make it a capable fit for repeatable workflows. Look elsewhere for a graphical interface, animated GIF preservation, or a workflow that does not depend on Python 3.10 or newer.