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Comparison

Onhand vs Private Diffusion

Two privacy-first image apps for iOS 26, both still unreleased on 12 September 2026. Here is what each one has said it does, and which reader should pick which.

By Onhand · Updated September 12, 2026

A compact curated model kit beside a larger private library of model crystals

The short answer

Neither app is on the App Store on 12 September 2026, so nobody can buy either one today. Private Diffusion lists ten text-to-image models, a 4x upscaler and a Mac version, and asks for at least 8 GB of memory. Onhand runs its free model on a 6 GB iPhone and adds photo editing, so the decision comes down to how much memory your device has and whether you want to work on your own pictures.

Side by side

What to checkOnhandPrivate Diffusion
Status on 12 September 2026Pre-launch, not on sale yet (waitlist)TestFlight beta, no App Store listing
MakerIndependent Onhand Studio appNumen Technologies Limited, Ireland
PlatformsiPhone and iPad, iOS or iPadOS 26iPhone, iPad and Mac, version 26
Memory neededFree pack runs on a 6 GB iPhone8 GB minimum, 12 to 16 GB for some models
Model choiceSmall curated catalog, packs 1 to 4.5 GBTen models listed, 2.5 to 12.9 GB
Where generation runsOn the device GPUOn the device, according to its website
Editing your own photosImage-to-image, inpainting, background removalNot listed on its website
UpscalingPlain resize, no AI upscalerLatent upscaler up to 4x
Iterating on a resultRefine loop, earlier versions keptNot listed on its website
PriceFree download, one-time Pro purchaseFree in beta, launch pricing not decided
AnalyticsLimited anonymous analytics, see /privacyNone at all, per its privacy policy
AccountNoneNone for the app, email to join the beta

Can you download either app today?

No. On 12 September 2026 neither app is for sale on the App Store, so every claim on this page is a statement of intent rather than something a buyer can test. Onhand is pre-launch, with a waitlist on this site. Private Diffusion is running a TestFlight beta that you join through an email waitlist on its website, and that site says pre-orders are coming to the App Store. Treat any comparison of two unreleased apps as a snapshot of a moving target, and check both sites again before you commit to either.

Because Private Diffusion has no App Store listing yet, it also has no star rating, no review history and no App Store privacy label. Everything below about it comes from its own website and privacy policy, read on 12 September 2026.

Which devices can run each one?

Memory decides this, not chip speed. Private Diffusion’s website lists a minimum of iOS, iPadOS or macOS 26 on Apple silicon with at least 8 GB of RAM, and says some of its models want 12 to 16 GB. Onhand needs iOS 26 or iPadOS 26 and no Mac version exists. Its free model pack is built to run on the developer’s test device, an iPhone 14 Pro with 6 GB of memory, which is also the floor the app is designed around. Onhand’s larger packs need more memory than the free one, and which packs a given iPhone can hold depends on how much memory that iPhone has free at the time.

The practical split is short. If your iPhone has 6 GB of memory, Onhand is the one with a model built for it. If you want the same app on a Mac as well as on your phone, Private Diffusion is the only one of the two that offers it.

How many models do you get?

Private Diffusion lists more, and this is its clearest advantage. Its website names ten models: Anima, Flux.2 Klein 4B, Krea 2 Turbo, Z-Image-Turbo, Juggernaut Z Fast, ERNIE Image Turbo, Chroma1-Flash, Boogu Image Turbo, Mage Flow Turbo and Kroma Turbo. Download sizes run from about 2.5 GB for the smallest to 12.9 GB for the largest, which is part of why the app asks for 8 GB of memory and more for some entries.

Onhand ships a smaller curated catalog of downloadable packs, roughly 1 to 4.5 GB each. The free pack is a fast Stable Diffusion class model of about 2 GB. Pro packs add more looks for portraits and scenes and a higher-quality model with better prompt following, FLUX.2 Klein 4B. The aim is a short list that has been checked on a 6 GB phone rather than a long one, which is a real trade: fewer options in exchange for a lower floor.

On generation speed, the developer measured about 7 seconds for a 512 pixel image with the free fast model and about 12 seconds with the XL pack on an iPhone 14 Pro, with the method described at /about. No comparable figure for Private Diffusion is quoted here, because timings from different devices and different models are not the same measurement.

Neither app is a workshop for your own weights. Custom model import, LoRA and ControlNet are not listed on Private Diffusion’s website, and none of the three exist in Onhand.

Can you edit your own photos?

This is where the two apps differ most. Onhand does photo editing on device: image-to-image with a strength control on every model, so you can restyle a photo you took; a Refine loop that keeps iterating on a result and keeps the earlier versions; masked inpainting, where you paint over an area and regenerate just that part, available with the free fast model only; resize; background removal; and style presets, with an on-device gallery that holds the history.

Private Diffusion’s website describes a text-to-image app. It lists a latent upscaler up to 4x, seven aspect ratios, three output sizes on most models, and negative prompts and prompt enhancement on select models. Image-to-image, inpainting, outpainting and background removal are not listed there. That is not the same as saying the app cannot do them, so check the current feature list before you decide on this point.

Onhand has gaps of its own that matter here. There is no outpainting, no AI upscaling of any kind (resize is plain resize, so the 4x upscaler is a genuine Private Diffusion feature with no Onhand equivalent), and no video. Negative prompts do nothing on Onhand’s Turbo models, because those models run at cfg 0, so style has to go in the positive prompt. Text and lettering inside a generated image depend on the model and are never reliable in either direction.

What happens to your prompts, and what will each one cost?

Both apps keep image generation on the device. Onhand runs generation and editing on the device GPU, so prompts, source photos and generated images are never sent to a generation server, and once a model pack is downloaded the app works in airplane mode. Private Diffusion says the same of itself: its website states that generation happens on your device, its privacy policy says the app collects no personal data and carries no analytics at all, and it works offline after a model is downloaded.

On analytics the two are not identical, and the honest version matters more than a tidy table row. Onhand uses limited anonymous analytics along with Apple and RevenueCat purchase services, all described at /privacy. Private Diffusion’s policy states it has none, and puts it plainly: “There is no Numen server in that loop.” If zero analytics of any kind is your bar, that is a point for Private Diffusion, and it should be. Neither app asks you to create an account, though joining the Private Diffusion beta needs an email address.

Price cannot be compared yet. Onhand is a free download with a fast model that is free to use, and Pro is a one-time purchase that unlocks more model packs, with no subscription, no credits and no limit on how many images you make. The Pro amount is not published here because it varies by storefront. Private Diffusion is free during its TestFlight beta and its website says launch pricing has not been decided, so there is no number to compare against.

Which one should you pick?

Pick Onhand if

  • Your iPhone has 6 GB of memory and you still want generation that runs on the device.
  • You want to work on photos you already have: restyle them, repaint one area, drop the background.
  • You want to keep refining a result and keep the earlier versions of it.
  • You want a free download with a one-time unlock rather than a price you cannot see yet.

Pick Private Diffusion if

  • You want the widest on-device model choice of the two, with ten recent text-to-image models listed.
  • You have 8 GB or more of memory, or you want the same app on an Apple silicon Mac.
  • You want a 4x upscaler, which Onhand has no equivalent for.
  • You want an app whose privacy policy states it carries no analytics at all.
  • You are comfortable running a beta while the launch price is still undecided.

Frequently asked questions

Is Private Diffusion on the App Store?

Not on 12 September 2026. Its website offers a free TestFlight beta that you join with an email waitlist, and says pre-orders are coming to the App Store. Because there is no listing yet, there is also no star rating and no App Store privacy label to read.

How much does Private Diffusion cost?

Its website says launch pricing has not been decided, and the TestFlight beta is free to take part in as of 12 September 2026. There is no published price to plan around. Onhand is a free download with a one-time Pro purchase, though that amount varies by storefront.

Which one runs on an iPhone with 6 GB of RAM?

Onhand. Its free model pack is built and tested on an iPhone 14 Pro, which has 6 GB, and that device is the floor the app is designed around. Private Diffusion’s website lists a minimum of 8 GB of RAM, with some of its models wanting 12 to 16 GB.

Is there a Mac version of Onhand?

No. Onhand is an iPhone and iPad app and needs iOS 26 or iPadOS 26 or later. There is no Mac app, no Android version and no web version. Private Diffusion lists iOS, iPadOS and macOS 26 on Apple silicon, so it is the one to look at for a Mac.

Can either app edit a photo I took myself?

Onhand can. It offers image-to-image with a strength control on every model, masked inpainting with its free fast model, background removal and resize, all on the device. Private Diffusion’s website describes text-to-image and does not list image-to-image, inpainting or background removal, so check its current feature list if editing is what you need.

Do either of these send my prompts to a server?

Neither app sends prompts or images to a generation server. Onhand runs generation and editing on the device GPU and works offline once a pack is downloaded, though it does use limited anonymous analytics and Apple and RevenueCat purchase services, described at /privacy. Private Diffusion’s privacy policy states it collects no personal data and carries no analytics at all.

Sources

Facts about other products come from their own listings and documentation, last checked on the date shown. Corrections are welcome at the address on the About page.