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CullKit vs Photo Mechanic: Culling Tools Compared

By Ingo D ·

Photo Mechanic has been the industry standard for photo culling for over two decades. Sports photographers, photojournalists, and agency shooters rely on it to ingest, triage, and caption thousands of frames before deadline. It is fast, keyboard-driven, and deeply integrated with the IPTC metadata ecosystem that newsrooms and wire services depend on.

But it is a desktop application. It runs on a Mac or a Windows PC, it expects files to be on a local or directly attached drive, and it does not work on a mobile device. If your library lives on a NAS, you are mounting the share first. If you want to cull on an iPad on the way home from a shoot, Photo Mechanic cannot help you.

CullKit is a different approach to the same problem. It is a mobile-first culling tool that runs natively on iPhone, iPad, and Mac. It connects directly to NAS shares over SMB and to the Synology Photos API, so you never mount a share or copy files first. Both tools write XMP sidecar metadata that Lightroom and Capture One read natively. But they serve different parts of the culling pipeline, and a photographer who understands both can combine them into a faster end-to-end workflow.

What does Photo Mechanic do well?

Photo Mechanic is built for speed. It was designed by photojournalists who needed to send a caption and a single frame to a news desk sixty seconds after the shutter clicked. Every feature in the application serves that deadline-first workflow.

It ingests cards with a customizable file-renaming engine. It renders embedded JPEG previews instead of RAW data, which is why it scrolls through a card of 45-megapixel RAW files at full speed on any modern computer. It loads a folder and presents a contact sheet in under a second. The keyboard shortcuts for tagging, rating, and applying colour labels are the same across Mac and Windows, and they become muscle memory after a single day of use. The IPTC Stationery Pad lets you apply captions, bylines, copyright notices, and location metadata to an entire take in one action. Code Replacement turns shorthand tokens like /sw9 into full caption strings, a feature that saves sports photographers dozens of keystrokes per frame.

For agency and press workflows, Photo Mechanic has no peer. It is the tool that moves images from camera to client faster than any other application on the market.

Where does Photo Mechanic fall short for NAS and mobile workflows?

Three gaps matter for the growing number of photographers who have moved their libraries to a NAS or who want to cull away from the desk.

No native NAS access. Photo Mechanic works with local filesystems. You can point it at a mounted network share, but that requires the NAS to be mounted as a drive letter on Windows or a volume on macOS first. The application has no built-in SMB client, no awareness of Synology Photos or QNAP shares, and no mechanism for browsing NAS directory structures without the operating system bridging the gap. If your working folder is smb://diskstation.local/photo, you must mount it before Photo Mechanic can see it.

No mobile version. Photo Mechanic runs on Mac and Windows only. There is no iPad version, no iPhone app, and no web client. If you want to do a first-pass cull on a tablet or a phone, you must use different software. For a photographer who shoots on location and travels with an iPad, the culling step must wait until they reach a laptop.

Limited storage reach. Photo Mechanic sees mounted volumes and attached drives. It does not connect to the Synology Photos API, does not browse NAS album structures directly, and has no built-in path to network storage. If your workflow involves multiple storage backends (a Synology for current projects, a QNAP for archives, an external SSD for location work), each must be mounted separately through the operating system before Photo Mechanic can use it.

These are not design flaws. Photo Mechanic was built before NAS devices were common in photographer workflows, and its speed advantage comes from being close to the filesystem. But the gaps are real for photographers whose libraries have outgrown a single desktop machine.

CullKit is an independent product. It is not affiliated with or endorsed by Camera Bits, Inc. (Photo Mechanic), Synology Inc., QNAP Technologies, Inc., TrueNAS / iXsystems, UGREEN Group, or Adobe (Lightroom). Compatibility claims only. Photo Mechanic is a trademark of Camera Bits, Inc.

How does CullKit handle culling differently?

CullKit approaches the culling problem from the opposite direction. Instead of requiring files to be local before you can work with them, it connects directly to wherever your photos already live and culls them at the source.

When you open CullKit, you choose a connection: a Synology NAS via the Photos API or SMB, a QNAP or TrueNAS share over SMB, a local folder on your Mac, or an external SSD plugged into your iPad. The app browses the folder structure on the device itself, loads thumbnails progressively, and opens a full-screen culling session that works with gesture swipes on iPhone and iPad and keyboard shortcuts on Mac. You never mount a share, import a catalogue, or copy files to a working drive first.

On iPhone and iPad, swipe right to keep a frame, swipe left to reject it. The quick-access bar below the image holds star ratings, colour labels, and a flag toggle. Auto-advance moves to the next frame the moment your gesture registers. On Mac, the same workflow runs from the keyboard: number keys for star ratings, P to pick, X to reject, 0 to clear, arrows to navigate. A culling session defines its scope (all frames, unrated only, or a filter by minimum rating), then runs through a full-screen rating pass, then presents a batch review before writing metadata. If the session is interrupted, crash recovery restores your exact position.

At session end, CullKit writes every star rating, reject flag, colour label, and tag to XMP sidecar files stored alongside your RAW images. This is the same XMP format Photo Mechanic writes, and the same format Lightroom, Capture One, and Darktable read.

CullKit vs. Photo Mechanic: what does each one offer?

The two tools are both culling applications, and comparing them across the dimensions that matter to a working photographer clarifies where each one fits.

Culling workflow

Photo Mechanic presents a contact sheet and a preview window. You navigate with arrow keys, tag with number keys, and apply IPTC metadata through the Stationery Pad. The workflow is fast and deterministic, with every action mapped to a keyboard shortcut. CullKit replaces the contact sheet with a full-screen swipe interface on iOS and a keyboard-driven viewer on Mac, with auto-advance and undo built into the culling session. Photo Mechanic is faster for captioning and metadata stamping. CullKit is faster for a pure rating pass on a mobile device, because your thumb never leaves the frame.

Platform availability

Photo Mechanic runs on Mac and Windows. It is a desktop application with no mobile companion. CullKit runs on iPhone, iPad, and Mac from a single SwiftUI codebase, with no web wrapper and no Windows or Android version. If your workflow is Apple-only and you want a culling tool that follows you from phone to tablet to desktop, CullKit covers all three. If you need Windows support or agency-standard IPTC templating, Photo Mechanic is the only option.

Storage reach

Photo Mechanic reads from local drives, mounted network volumes, and attached media. It does not have its own network client. CullKit connects directly to Synology Photos via its native API, to any NAS over SMB (QNAP, TrueNAS, UGREEN, Asustor), to local folders on your Mac, and to external SSDs plugged into your iPad. No mounting, no drive letter, no operating system bridge. If your library lives on a NAS and you want to cull without sitting at the desk that has the share mounted, CullKit’s direct-connect approach is the key difference.

Metadata and XMP

Both tools write XMP sidecar files that Lightroom, Capture One, and Darktable read natively. Photo Mechanic additionally writes IPTC metadata fields and supports the full IPTC Core and Extension schemas with the Stationery Pad. CullKit writes star ratings, reject flags, colour labels from the Lightroom palette, and Dublin Core keyword tags. If your workflow relies on IPTC captioning, bylines, copyright notices, and location fields applied in bulk, Photo Mechanic covers that ground. If you need portable star ratings and labels that flow into your editor without an import step, both tools deliver the same result.

Speed and interface

Photo Mechanic is fast because it works with embedded JPEG previews rather than RAW data, and because it operates directly on the filesystem. CullKit renders progressive previews on device from full-resolution images streamed over the network. Over a fast local network (5GHz Wi-Fi or wired) with a modern NAS, the per-frame speed is comparable for rating decisions. Photo Mechanic holds the edge for lightning-fast contact-sheet browsing and for ingest-time file renaming. CullKit holds the edge for on-the-go culling, because the device in your hand does not need a desk.

Privacy

Both tools are local by design. Photo Mechanic processes files on your computer and writes metadata to sidecars on your drive. CullKit processes every frame on your device, writes ratings to your own storage, and stores credentials in your device Keychain. There is no CullKit server and no cloud middleware. If you chose a NAS or a local drive to own your data, both tools respect that choice. (For more on CullKit’s privacy model, see the privacy FAQ.)

Can CullKit replace Photo Mechanic?

For most photographers, the answer is no, and it does not try to. CullKit and Photo Mechanic sit at opposite ends of the culling pipeline, and they complement each other more than they compete.

Photo Mechanic is the right tool when you need IPTC templating, code replacement for sports captioning, ingest-time file renaming with variables, and the ability to send a captioned frame to a client or wire service within minutes of shooting. It is the desktop powerhouse for agency, press, and deadline workflows, and it has no equivalent in the mobile space.

CullKit is the right tool when you want to do a first-pass cull on an iPad on the train after a wedding, or when your library lives on a NAS and you do not want to mount shares and copy files before you start rating. It is the mobile-first tool that adds culling to any storage your photos already live on, and it hands your selects to your desktop editor as XMP sidecars.

A photographer who uses both might run Photo Mechanic on the desktop for ingest, file renaming, and IPTC stamping, then switch to CullKit on the iPad for the first-pass cull while travelling, review selects on the Mac with CullKit’s keyboard mode, and finish in Lightroom with all ratings already in place. Both tools write the same XMP format. Both feed the same editor. Neither locks you in.

Troubleshooting

CullKit cannot connect to my NAS. Confirm SMB is enabled on your NAS (DSM: Control Panel → File Services → SMB; QNAP: Control Panel → Network & File Services → Win/Mac/NFS → Microsoft Networking; TrueNAS: Services → SMB). Verify the share path: Synology shares typically use smb://diskstation.local/photo, QNAP uses smb://<NAS-IP>/Multimedia, and TrueNAS uses the share name you created in the SMB service. If using a local IP address and it stopped working, your DHCP lease probably changed. Assign a static IP to the NAS or use Bonjour hostnames.

Ratings set in CullKit are not appearing in Photo Mechanic or Lightroom. Both tools read XMP sidecars, but not all editors refresh metadata automatically. In Lightroom, select the folder in the Library module and run Metadata → Read Metadata from Files. In Photo Mechanic, the app reads embedded XMP and sidecar XMP automatically for files it browses, but make sure the sidecar has the same base filename as the RAW file (DSC_4723.NEF and DSC_4723.NEF.xmp in the same folder).

CullKit feels slower than Photo Mechanic over Wi-Fi. Photo Mechanic works with embedded JPEG previews on a local drive. CullKit streams full-resolution RAW previews over the network and renders them progressively on device. A 5GHz Wi-Fi connection or a wired NAS makes a noticeable difference. If you are on 2.4GHz and working with 45-megapixel RAWs, expect some render delay between frames. For the fastest CullKit experience, connect via USB-C SSD rather than Wi-Fi.

I use Photo Mechanic for IPTC captioning. Can CullKit do that? CullKit writes keyword tags to the Dublin Core schema in XMP but does not have an IPTC Stationery Pad, code replacement, or bulk captioning. If your workflow depends on IPTC metadata for client delivery or agency submission, keep Photo Mechanic for that step. CullKit handles the rating and culling pass, and the IPTC metadata you apply later coexists with CullKit’s ratings in the same XMP sidecar.

Add mobile culling to your Photo Mechanic workflow

Photo Mechanic handles the heavy lifting at the desktop: ingest, rename, caption, and deliver. CullKit handles the step that happens before any of that, and the step that fits into the gaps in your day: the first-pass cull, on the device you already carry.

You keep Photo Mechanic for the deadline workflow it was built for. You add CullKit for the mobile culling that lets you finish a rating pass on the train, on the sofa, or on location, with every star and flag already waiting in Lightroom when you sit down at the desk. The two tools write the same XMP format. They feed the same editor. They just go about the cull from different directions, and together they close the gap that neither one covers alone.

CullKit is available on the App Store for iPhone, iPad, and Mac. The free tier lets you browse any connected library: Synology Photos, SMB NAS shares, external SSDs, and local folders. The Pro tier (7-day free trial, then monthly or yearly) unlocks the full culling workflow: star ratings, reject flags, colour labels, XMP sidecar writing, and folder organisation.

A built-in demo mode with seeded sample data lets you experience the full swipe-based culling flow before connecting your own library or committing to the trial.

Download CullKit on the App Store

CullKit is an independent product. It is not affiliated with or endorsed by Camera Bits, Inc. (Photo Mechanic), Synology Inc., QNAP Technologies, Inc., TrueNAS / iXsystems, UGREEN Group, or Adobe (Lightroom). Compatibility claims only. Photo Mechanic is a trademark of Camera Bits, Inc.

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