Privacy

In short

Glazecalc keeps what it needs to run your account, and nothing more. There are no ads, no analytics and no tracking. Your data is never sold, and the only company that handles it is Amazon Web Services, which hosts the site and sends its email.

Who is responsible

Glazecalc is a free, open-source, non-profit project, run by its owner, Aaron Filson, in the United States. He decides what happens to your data, so in data protection law he is its "controller".

To ask about your data, or to use any of your rights, write to privacy@glazecalcapp.com. You can also open an issue on GitHub, but issues are public: never put your email address or anything personal in one. Most things about your data you can do yourself on your account page.

What is kept, and why

• Your account: your email address, and your password, stored only as a one-way hash (bcrypt), never as the password itself. Your settings (such as language, region and units) and the list of materials you have on hand are kept with it. An account needs an email address, to sign in and to reset a forgotten password. When you create an account, a link is sent to the address to confirm that it is yours; until then, mail goes to it only when you ask, such as for a password reset.
• Prices, if you give any: what you pay for each material, per kilogram, and the currency they are in, for the cost of a batch. They are business data, kept with your account and private to it: they are never part of a recipe, so nothing you share shows them. Download my data includes them, and deleting the account deletes them. A trial's prices move into your account with its records, for materials you have not priced, when both are in the same currency.
• Changing your email: the date your address last changed, so that a request to turn off two-step sign-in is never taken from a new address in the 30 days after.
• Two-step sign-in, if you turn it on: whether it is on; the key your authenticator app shares with Glazecalc, encrypted; for each passkey, its public key (which cannot sign in on its own) with the id and details your device gives it, the name you gave it, and when it was added and last used; your recovery codes, only as a keyed one-way hash, so nobody can read them back; and, if someone enters your password but does not finish the second step, when Glazecalc last emailed you about that (at most once a day). While you sign in, between your password and the second step, the server keeps a note of the sign-in for 5 minutes, and the page holds a short token in its memory only: no new cookie, nothing in your browser's storage.
• Google, GitHub or Microsoft, if you sign in with one: the provider's own id for you (a number or code that never changes; for Microsoft, together with the id of the directory your account belongs to: your organization's, or Microsoft's own for personal accounts), when you linked it and when you last signed in with it, and whether your account has a password of its own. Nothing else from the provider is kept: not your name, your picture or any key to your account there. While you sign in, the server keeps a note of the sign-in, with the email the provider says is yours when it is needed: for a new account, where it becomes your account's email (an email from Microsoft is not taken on trust: you confirm it with the link we email you, as when you sign up), or, when a Glazecalc account already has that email, to link Google or GitHub to it once you sign in to that account (Microsoft is linked only from the account page). The note, and the email in it, is deleted within about 10 minutes.
• What you save: your recipes, materials, additives, notes, firing logs and advice, as you wrote them. Only you can see them, unless you share a recipe by link.
• The Trash and earlier versions: what you remove from a list waits in the Trash, whole, so you can put it back; and each change you save to a record keeps the record as it was just before, so you can undo the change.
• Recipes you share by link, if you share any: which recipe, when its link was made and whether it shows the recipe's notes, with a one-way hash of the link (never the link itself). Anyone who has the link can see the recipe as it is now, with its unity formula, and its notes if you chose to show them; never your email, your account or any prices. Shared recipes are kept out of search engines, and the link never reaches the server's logs. To stop abuse, the shared recipes opened from each IP address are counted, in memory, for 15 minutes. A trial cannot share.
• Access tokens and connected apps, if you make or approve any: for each, its name, what it may do, a one-way hash of the token (never the token itself) and its last 4 characters, and when it was made, last used, expires and was revoked.
• What tokens and apps did: a line for each record an access token or connected app created, changed, moved to the Trash, put back or undid: when, which token or app, what it did and the record's title, cut short. Never a note's text or anything else in the record. Changes you make on the website are not listed.
• Limits on how often: to stop guessing and runaway scripts, counts of sign-in tries, sign-ups, reset requests and trials by IP address or account, of access tokens that do not work by IP address, of requests made with access tokens, by account (120 a minute and 5,000 a day), of changes made with access tokens, by account (60 a minute and 5,000 a day), of records each access token moves to the Trash, by token, of shared recipes opened and of share links that open nothing, by IP address, and of requests to the tools for AI assistants (MCP): 60 a minute and 2,000 a day by IP address, or 300 a minute and 20,000 a day by account when an access token is used, with at most 10 substitutions or matches a minute.
• A trial ("Try it now"): no email or password, only a made-up name such as "speckled quiet kilns". If you sign in to an account on the same browser during a trial, what you made in the trial moves into the account.
• Password reset and email links: which account asked, when, the address a link to confirm an address was sent to, and a fingerprint of each link (not the link itself).
• Logs: the web server records each request: your IP address, the time, the page asked for and the name of your browser. The app records errors with the page they happened on, never your email address.
• Deleted accounts: the account's id number and when it was deleted, and nothing else, so that a restored backup cannot bring the account back.
• Email problems: if mail to your address bounces or is reported as spam, Amazon's email service puts the address on a list not to mail again, and sends the owner a notice that includes the address.
• Mail you send to Glazecalc: mail to privacy@glazecalcapp.com and Glazecalc's other addresses is checked by Amazon for spam and viruses, kept in a private store, and forwarded to the owner's own inbox (Gmail).

The legal basis

• Running your account, keeping what you save, and the emails about your account are the service you asked for: the legal basis is the contract between you and Glazecalc (GDPR Article 6(1)(b)).
• Keeping the site safe and working: the logs, the limits on how often anyone can try to sign in, the backups, the record of deleted accounts and the list of addresses not to mail. These rest on Glazecalc's legitimate interest in security, preventing abuse and not losing your work (Article 6(1)(f)). They are kept briefly and used for nothing else. You can object to them by writing to the address above.

Nothing about you is decided automatically, there is no profiling, and nothing is used for advertising.

Where it is kept, and who handles it

Glazecalc runs on Amazon Web Services (AWS): the server (EC2), the backups (S3) and the email (Simple Email Service), all in the United States, in Oregon (us-west-2). AWS handles the data only on Glazecalc's behalf, under its data processing terms. No one else receives it.

If you live in the EU, the UK or Switzerland, your data goes to the United States. Amazon says it is certified under the EU–US Data Privacy Framework and its UK and Swiss extensions, and AWS's terms include the EU's Standard Contractual Clauses, which would still apply if the Framework, now challenged in court, were struck down. The owner and AWS are both in the US, and US law can require them to hand over data.

Your browser loads nothing from other websites: no fonts, scripts, images or analytics from elsewhere, and the site's security settings block them. Links to GitHub and other sites are followed only when you click them.

Signing in with Google, GitHub or Microsoft is your choice, and only happens when you press its button. Your browser then goes to that provider, which sends Glazecalc its id for you and your email. Each is a separate company, responsible for what you share with it under its own privacy policy. No script or image from any of them loads on Glazecalc's pages.

Where your account is kept, and your choice

Glazecalc is a free, open-source project. Accounts, and everything they hold, are kept on servers in the United States, wherever you live, as described above.

You do not need an account to read the guides, and you can try the calculator with "Try it now", with no email address or password. A trial is kept on the same servers for 14 days.

Anyone can run their own copy of Glazecalc, on their own computer or server: the code is free on GitHub.

Whether to create an account here, knowing it is kept in the United States, is your own decision.

Glazecalc is provided as is, without warranty. Its maintainers accept no responsibility or liability for your decision to create an account, or for where its data is held.

How long it is kept

• Your account and what you save: until you delete them. Accounts are not removed for being unused.
• The Trash and earlier versions: a removed record 30 days after you removed it, or until you delete it for good or empty the Trash; earlier versions 90 days, and only the last 20 of each record (and the one from before an access token's changes) and the last 20,000 of the whole account, but never longer than the record: while it is in the Trash its versions go when it does. Both go at once when you delete your account.
• Share links: until you stop sharing the recipe, make a new link for it, move it to the Trash or delete your account. Putting the recipe back from the Trash does not share it again. Resetting your password or signing out everywhere also stops all your links; changing your password does not.
• Access tokens and connected apps: each until 30 days after it expires (every one expires, within a year at most), or until you delete your account. A password reset or "Sign out everywhere" stops them all at once.
• What tokens and apps did: 90 days, or until you delete your account.
• Limits on how often: the counts are kept in the server's memory only, for 1 minute to 24 hours, and are lost when it restarts.
• A trial: 14 days from its start, then it is deleted with everything in it, unless you create an account to keep it.
• Password reset and email links: a reset link works for 30 minutes and its record is deleted after about an hour; a link to confirm an address works, and is kept, for 24 hours.
• Two-step sign-in: each authenticator app, passkey and set of recovery codes until you remove it, turn two-step sign-in off or delete your account. A sign-in waiting for its second step is deleted after 5 minutes, and an app or passkey you began to add but did not finish, after at most 10.
• Google, GitHub or Microsoft: each link until you unlink it or delete your account. A sign-in under way is deleted after 10 minutes.
• Backups: encrypted copies of the database are kept 30 days, and copies of the server's disk 7 days. So a deleted account is gone from every backup within 30 days.
• The record of a deleted account: 37 days, just longer than any backup.
• Logs: the web server's, 14 days. The app's and the database's own logs are limited by size (50 MB each), which on a quiet site reaches back several days. The copies of the server's disk keep logs for up to 7 days more.
• The list of addresses not to mail: until the owner removes an address, which he does each month for addresses that no longer belong to an account. The owner deletes bounce notices within 30 days.
• Mail you send to Glazecalc: 30 days in Amazon's store, and in the owner's inbox as long as it takes to answer you. For a request about your data, a short note (when it came, what was asked and what was done) is kept for three years.

Your rights

You can see, correct, take and delete your data. Most of it you can do yourself on your account page:

• See it and take it with you: Download my data saves everything in one file (JSON), including the names and dates of your two-step sign-in methods (never their keys or codes), and your recipes and materials as spreadsheets (CSV).
• Correct it: change your settings and your records at any time. To change your email address, open the link sent to the new address; the old address, if it was confirmed, is told of the change, and every device is signed out.
• Delete it: Delete my account removes your account and everything you saved at once, and "Discard trial" does the same for a trial. Copies in backups are gone within 30 days.
• Sign out everywhere: ends your account's sessions on every device.

For anything else, such as asking for your data to be held back from use while a mistake is put right, or objecting to how it is used, write to privacy@glazecalcapp.com. It is free, and you will have an answer within a month. You will only be asked to show the account is yours, by signing in or by opening a link sent to its address, never for an ID.

If you are not satisfied, you can complain to a data protection authority: in the EU, the authority in your country, and in the UK, the Information Commissioner's Office.

Cookies and browser storage

Glazecalc sets two cookies, the second only while you sign in with Google, GitHub or Microsoft, and keeps a few small values in your browser. Each is there for something you asked for: staying signed in, signing in with Google, GitHub or Microsoft, or remembering a choice you made. None tracks you and none is shared, so the law does not require asking first, and there is no cookie banner.

You can clear any of these in your browser's settings at any time. Deleting your account removes the sign-in note and every setting kept here.

Children

Glazecalc is a tool for potters and is not directed at children.

Changes

If this notice changes, the date at the top of the page changes too.