FileDial › Guides › Mac workflow
Automatically process files dropped in a folder on Mac
By Himanshu Ranjan · Updated 8 November 2026
A watched folder runs a task on anything dropped into it. On a Mac you can build that yourself with Automator, and FileDial includes watched folders that run a recipe, a chain of its tools, on every file you drop in. Keep input and output separate, and make sure the job writes copies rather than overwriting.
The idea
A watched folder, sometimes called a hot folder, removes the last manual step. Instead of selecting files and choosing a tool, you drop files into a folder and the task runs. Typical uses are shrinking photos before upload, stripping location from images, converting incoming HEIC, or compressing scans.
Ways to build one on a Mac
Apple's Automator guide describes Automator as the app for building workflows without scripting, and Automator is the traditional way to attach a workflow to a folder. Shortcuts is Apple's current automation app, but Apple's pages I checked do not describe folder triggers, so no steps are claimed for it here. Check what your macOS version offers before planning around it.
If you build your own, test it on duplicates first. A workflow that overwrites originals in a folder it also watches can loop or destroy files.
FileDial's watched folders
In FileDial, recipes chain tools, for example Convert › Convert to JPG then Privacy › Remove location, and watched folders run a recipe on anything dropped into a folder. Tools work in batches, so a folder of 300 photos is one job; a batch of 300 photos converted in 5 seconds in our own measurement on a MacBook. Results are saved as new files beside the originals, never over them unless a tool says so up front, and each result has Undo.
Everything runs on the Mac and files are never uploaded, so a folder of client photos or scanned documents stays local.
Design rules for unattended folders
Some rules prevent most problems.
Treat the watched folder as an inbox and write results somewhere else, or at least in a place the job does not watch. Name the folder for what it does so no one drops the wrong file in.
- One purpose per folder, named for it, such as Clean photos
- Originals kept: choose tools that write copies
- Test with three dummy files before real ones
- Check the first week of results by eye
- Keep a backup of anything irreplaceable
Examples worth setting up
A photo-sharing folder: convert to JPG and remove location, so anything you drop in is safe to post. A scan inbox: PDFs dropped in are compressed with Compress › Compress PDF (strong). A client-proof folder using Share › Client proof… for a watermarked, metadata-free JPG. Each is one sentence of description, which is the test for whether a task is worth automating.
Avoid watching folders that sync with cloud services in ways you do not control, since changes made by a job can sync back. For a wider look at automation, read the guide on automating repetitive file tasks.
Failure modes to plan for
Unattended automation fails in predictable ways, and each has a cheap defense. The first is a loop: a job that writes its output into the folder it watches processes its own output again. Always send results to a different folder, or use a tool that writes beside the original into a place the job ignores.
The second is partial files. A large file still copying into the folder can be picked up before it is complete, which gives you a broken result. Drop files in from a local folder rather than a slow network share, and wait for large copies to finish before walking away.
The third is the wrong input. If anyone, or any app, can write to the folder, odd files arrive: a hidden file, a file type the recipe does not expect, a document with a password. Name the folder clearly, restrict it to one source, and check the results folder at the end of the first few days.
The fourth is cloud sync. Placing a watched folder inside a synced location means every output is uploaded and may sync back to other devices, which defeats the privacy value of local processing and may re-trigger jobs. Keep sensitive watched folders on local, encrypted storage.
The fifth is trust without review. A recipe that works on three test files can still misbehave on the hundredth. Review a sample from each week's output and keep originals until you are confident. FileDial's result cards show what changed and the size before and after, and every result has Undo.
When a task is occasional rather than daily, skip the folder entirely. Selecting files and running the tool takes seconds and puts you in control of each run.
Questions
What is a watched folder?
A folder that triggers an action on files placed in it. You drop files in, the task runs and the results appear, which saves selecting files and choosing a tool each time. It suits inputs that always arrive in one place, such as a folder where you collect photos to share.
Will a watched folder overwrite my files?
It depends on the job. FileDial saves results as new files beside the originals unless a tool says so up front, and every result has Undo. If you build your own, choose steps that write copies and send output to a different folder so the job cannot overwrite or reprocess files.
Can I use a watched folder on Shortcuts?
Apple's Shortcuts pages that were checked for this guide do not describe folder triggers, so check what your macOS version offers before planning around it. Automator is Apple's long-standing tool for folder-based workflows, and the Automator guide describes building workflows without scripting.
Is a watched folder safe for sensitive files?
If the tools run locally, nothing is uploaded, and FileDial runs entirely on the Mac. Also keep the folder on an encrypted disk, avoid cloud-synced locations for sensitive files, and remember that anyone with access to the Mac can read the folder's contents.