Last updated: October 15, 2026
Hellbox (formerly Font Proof) is a Mac app made by Minim Industries. This policy covers this website, the Mac app, and the optional Font Proof by Hellbox service in ChatGPT.
The Mac app processes your fonts and proofs locally. The optional ChatGPT service processes files you attach on our hosted infrastructure, as described below. The only things the Mac app sends are a license check and an update check, and we log those (without your license key itself) so we can see how many people use Hellbox each day and which versions are in use. Details below.
This website uses Google Analytics to understand which pages people visit. That's it.
If you accept cookies, we use Google Analytics to collect anonymous information about how visitors use this site. This includes pages viewed, referrers, approximate location (country level), browser type, and device type. We use this to understand which features people care about.
You can decline cookies via the banner. If you decline, no analytics data is collected from your visit.
Google's privacy practices are described at policies.google.com/privacy.
If you buy Hellbox, the transaction is handled by Lemon Squeezy, our payment processor and Merchant of Record. They collect billing information needed to process the sale (name, email, payment details, billing address for tax purposes). Their privacy policy is at lemonsqueezy.com/privacy.
We receive your name and email so we can send you your license key and respond to support requests. We do not share this with anyone else.
Hellbox runs locally on your Mac. It does not transmit your fonts or proof files anywhere, and does not require an account. Its network activity is limited to two things:
License checks. On launch, the app confirms your license is still valid with our licensing provider (Lemon Squeezy). This sends your license key and a per-device identifier, never your fonts or work. That request passes through a server we run, which records that a license was checked on a given day, along with the device identifier and the app version. We store a one-way hash of the license key, not the key itself. We use this to know how many people are actively using Hellbox and to help you if a license or activation misbehaves. It is not shared with anyone.
Update checks. Once a day, the app asks our server whether a newer version exists. That request carries the app version and nothing about you or your machine; we count these to see which versions are in use.
Feature usage. Once a day, alongside the license check, the app sends the names of the features that copy used since its last report: for example "Glyph Set" or "Layer mode". These are fixed labels from a short list inside the app. They never include your fonts, your proofs, file names, text, or settings values. They are stored with the same hashed license key as the license check, so we can see which features are used and by how many people, and get in touch when a feature someone relies on is about to change. You can turn this off in Settings, under License, and see exactly what the app would send.
Nothing else leaves the app. There is no crash reporting and no third-party analytics inside Hellbox.
When you ask the ChatGPT service to make or open a proof, it receives the files you attach for that request, including fonts, proof documents, and any linked text you supply. It also receives the proof text and settings needed to carry out your requested edits. We use these to render previews, PDFs, and editable .fontproof documents, and to return results to your ChatGPT conversation.
Rendering and temporary storage run on Cloudflare. OpenAI handles your conversation and attachments under its own policies. This service does not require a Hellbox account, Mac installation, or license key. We do not use uploaded fonts or proof text to train models, sell them, or add them to a shared font library.
Completed proofs expire approximately one hour after rendering. Each revision is a separate temporary proof with its own expiry. Expired proofs are unavailable and their stored font and artifact data are scheduled for deletion. You can ask the service to delete a completed proof sooner; this affects that proof revision, not other revisions, your ChatGPT attachments, or files you have already downloaded. Save downloads you want to keep.
Proofs and download links contain private access tokens. Anyone with a valid link can retrieve its result until it expires, so do not publish those links or tokens. Editable .fontproof downloads embed the fonts you supplied; only upload and share fonts you have permission to process and embed.
We use aggregate attempt counts and temporary render identifiers to limit service load. Infrastructure providers may process network and operational metadata to deliver and secure the service. Cloudflare's and OpenAI's own retention policies apply to their operational records and your ChatGPT data; the one-hour proof expiry is not a promise to delete your conversation or provider logs. Contact jake@hellbox.com for service privacy questions.
Questions about this policy? Email jake@minim.industries.