Privacy

Last updated 12 November 2026

My short version: the app makes everything on your Mac, has no account, analytics or tracking, and never uploads your pictures, logos, names or projects. The formal version follows.

This policy covers the Skynthesis app for macOS and the website at skynthesis.app. Skynthesis is made and sold by its developer, a sole proprietor based in California, United States (“we”).

What stays on your Mac

• Your projects, the images and logos you add, and the name you type for a skin. Projects live in your user Library under Application Support/Skynthesis, and finished skins go to Serum 2’s Skins folder. They leave your Mac only if you choose File > Email Me This Skyn…, as described below.
• Your Pro licence record, kept in your login keychain and in a file in the app’s folder.
• The count of free Skyns you have kept; on a Mac, Apple also keeps that count for us, as below.

What the app sends, and to whom

Only five parts of the app can reach the network. Each is listed here with exactly what it sends.

• Texture search (Skynthesize). To find fresh textures, Skynthesize sends a theme search word, such as “velvet” or “neon”, to Poly Haven, the Art Institute of Chicago and Openverse, then downloads the matching CC0 or public-domain pictures from those libraries or from the site an Openverse result points to. Requests to those three services also carry the app’s name and version and a link to its release page, as they ask; a picture fetched from another site carries only the app’s name. Your pictures, your skin’s name and your files are never part of these requests. You can turn this off with the Online option under Sources in Skynthesize. These services see your IP address, as any website does, under their own privacy policies.
• Update check. The app asks updates.skynthesis.app for the latest version. The request carries only the app’s name and version. If you install an update, the disk image downloads from the same host. Cloudflare serves that host and processes the IP address of each request.
• Licence (Pro only). Buying, activating or deactivating Pro, and re-checking the licence (weekly, or at launch while a purchase or refund is settling), send the key (or your purchase claim and, from the app’s Buy button, which screen it was on), random install ids and the app’s version to our own server at skynthesis.app. While a purchase you started in the app is being paid, the app asks every few seconds. Install ids are made up by the app and say nothing about your Mac. No file or personal detail is sent. Cloudflare serves the licence server and processes the IP address of each request.
• Free Skyns (Mac, from version 0.6.0). Before you keep each free Skyn (in 0.6.0 and 0.6.1, before each free Skynthesize), the app asks our server at skynthesis.app for it. It sends a random one-time ID and a device token that macOS makes for this Mac (macOS may contact Apple to make it). We pass the token to Apple’s DeviceCheck service, which keeps two bits for this Mac: its free-Skyn count, shared by every user account on the Mac. Apple tells us only that count and the month it last changed. We keep none of it. Cloudflare serves the licence server and processes the IP address of each request.
• Email Me This Skyn (only when you choose it). When you pick File > Email Me This Skyn… and press Send, the app sends the following to our server at updates.skynthesis.app:
  • the finished skin folder, as a zip. It includes any picture you placed in the skin;
  • its share card;
  • the skin’s name;
  • its Skyn link (theme, wildness and seed), if a Skynthesis made it;
  • the email address you typed, and whether you ticked “Skynthesis news”.

  We store the zip for 7 days so the link in the email works, then delete it.

  We pass the address, the skin’s name, the card and the link to Resend, Inc. (resend.com), which delivers the email for us under its data processing terms. Resend keeps a record of each email for up to 30 days.

  We don’t keep your address after sending unless you ticked “Skynthesis news”. If you did, it joins the same list as the download form, and every email has a link to leave it.

  To stop the form being used to mail strangers, we count sends for two days:

  • per IP address;
  • per email address, as a one-way fingerprint of it rather than the address itself.

  Cloudflare serves the server and processes the IP address of each request. Resend processes data in the United States.

Downloaded pictures are checked on your Mac by Apple’s on-device Vision framework (for faces, text and labels) before Skynthesize uses them. Nothing about them is sent anywhere.

Buying Pro

Pro is sold through Stripe Managed Payments. Link (Stripe) is the merchant of record and the seller of every purchase. At checkout, Stripe and Link receive a random purchase claim id from the app and, from the app’s Buy button, which screen it was on (like keep or menu), and nothing else from your Mac. Stripe and Link collect your name, email address, billing details and payment information, handle tax, and send your receipt, under their own privacy policies. Your licence key is shown on the page after checkout. Our licence server stores no email address and no plaintext key: only a hash of the key (and of any purchase claim), the Stripe checkout and payment ids, and install ids with the date each was first and last seen. We use them only to provide the licence and support, and keep them as long as the licence exists. We do not delete them when a payment is refunded, because they are what stops a refunded key from working. If you write to us about a purchase, we can look it up in Stripe. We never see your card details.

The website

• The site sets no cookies except the link cookie below, and loads no analytics, advertising or third-party scripts or fonts.
• It is served by Cloudflare, which processes your IP address to deliver and protect the site. Cloudflare also serves the update feed and the licence server, and processes IP addresses for those requests too.
• Waitlist. If you join, we store your email address and the time you joined. We use your email address only to write to you about your copy of Skynthesis. We keep it until you ask us to delete it, or until 12 months after you joined, whichever comes first. To stop abuse, we also keep your IP address with a count of that day’s sign-ups for two days.
• Email when you download. To download Skynthesis from this site you give an email address. We store it and the time you gave it, in a list of its own (not the waitlist), and use it only to write to you about Skynthesis. We keep it until you ask us to delete it, or until 12 months after you last gave it, whichever comes first. To stop abuse, we also keep your IP address with a count of that day’s sign-ups for two days.
• If you ask for your key at /key, we use that address once to look up your purchase in Stripe and email you the link, and we don’t keep it. If you download on a phone, we email that address the download links once.
• Which link sent you. If you reach the download form from a creator’s link or from one of our posts (Instagram, TikTok, YouTube or Reddit), we add one to a count for that link and that day. The count holds only the link’s short name and the date, never your email address, your IP address or anything else about you. Each count is deleted 12 months after its day ends. A repeat download counts again, so it counts downloads, not people.
• If you arrive from one of our links, we keep a cookie for 30 days with the name of that link only, so we know which post brought you. It holds nothing about you.
• Problem reports. Reports you send, by the form or by email: the text, an email address only if you give one or send from one, and, only if you tick the box, the app’s usage counts (numbers such as how many previews you made). We keep them up to 12 months on our server to fix bugs, and never share or sell them.
• Downloads. The Mac disk image is downloaded from updates.skynthesis.app. Cloudflare serves that host and processes the IP address of the request.

Email to us

If you write to us, we use your message and address to answer you, keep them only as long as needed to help you, and then delete them.

Sharing

We do not sell or rent personal information, and we share it only with the services named above, as needed to run them, or when the law requires it.

Your choices and rights

You can ask us for a copy of the personal information we hold about you, or ask us to correct or delete it, by writing to support@skynthesis.app. For purchase records held by Stripe and Link, you can also contact them directly.

If you are in the EU, the EEA or the UK, the controller of the personal data described here is the developer of Skynthesis (a sole proprietor in California, USA), reachable at support@skynthesis.app. We rely on your consent for the waitlist (you can withdraw it at any time); on our agreement with you for licence records and licence checks and for emailing you a skin you asked for; and on our legitimate interests in keeping your copy up to date, answering your emails, and protecting the site and waitlist from abuse. We keep licence records for as long as the licence exists. Your data is processed in the United States, where we and Cloudflare are based. You can also ask us to restrict or stop using your data, or for a copy in a portable form, and you can complain to your local data protection authority (in the UK, the ICO).

If you are in California: we do not sell or share your personal information, and we do not use it for targeted advertising.

The site and app do not track you across other sites, so they work the same whether or not your browser sends a Do Not Track signal.

Children

Skynthesis is not directed at children under 13 (under 16 in the EU and UK), and we do not knowingly collect their personal information.

Changes

If this policy changes, we will update the date above and post the new version on this page.