Privacy Policy

1. Who we are and what this covers

STACK (“Stack”, “the Service”) is a free vault for collectors operated by bullionOS (“bullionOS”, “we”, “us”). This Privacy Policy explains what information the Service collects, how it is used, who it is shared with, and the choices you have. It applies to stack.bullionos.co and any other address where Stack is offered.

It does not cover the bullionOS software used by dealers, the bullionos.co website, or any dealer’s own handling of your information. A dealer you buy from or sell to is an independent business with its own privacy practices.

2. Information you give us

Account details: your email address, the name you choose to give, and your password. Your password is stored only as a one-way cryptographic hash; we cannot read it.

Vault records: the holdings, purchase costs, dates, grades, certification numbers, notes, sales, want-list items and preferences you enter or import.

Messages you send us, such as a support request.

3. Information we receive when you connect a dealer

A dealer that runs on bullionOS can invite you to connect. To send the invitation, the dealer gives us the email address and name on the customer record they hold for you.

If you accept, Stack reads from that dealer’s records the completed invoices issued to your customer record (invoice number, date, items, quantities, prices, tax, total and amount paid) and shows them to you. We do not copy a dealer’s internal notes, pricing workings or other customers’ information into your vault.

Nothing is shared with you from a dealer, and the dealer is told nothing beyond the status of the invitation, until you accept.

4. Information collected automatically

A sign-in cookie that keeps you signed in on your browser. It is strictly necessary for the Service to work. Stack sets no advertising or cross-site tracking cookies.

Technical data needed to run and protect the Service: your IP address, used briefly to limit abusive sign-ups and sign-in attempts, and ordinary server logs kept by our hosting providers (time, address requested, response).

Preferences stored only on your device, such as light or dark appearance and whether your vault is hidden.

5. Camera, photos and location

The camera opens only when you start a scan. When you ask Stack to identify a piece, the photo you take or upload is sent to our servers and to our image-reading provider so it can be read. It is used for that one reading and is not kept in your vault or on our servers afterwards. Avoid photographing anything you would not want read, such as a face or a document.

To check a graded holder, its certification number or barcode is sent to the grading company. To find the piece in the coin catalog, a description of it (country, denomination, year) is sent to the catalog provider. Neither receives your name, your email address or your collection.

Your location is requested only if you choose “Use my location” in the coin-shop search. It is used for that one search and is not stored in your vault.

6. How we use information

To provide the Service: keep and display your vault, value it at current prices, show invoices from connected dealers, and keep you signed in.

To communicate with you about your account: confirm your email address, deliver a dealer’s invitation, reset your password, and send notices about the Service or these terms. We do not send marketing email from Stack without your consent.

To secure, maintain and improve the Service, prevent abuse, and comply with law.

We do not use your vault to make automated decisions about you, and we do not use it to train artificial-intelligence models.

7. What dealers can and cannot see

A dealer never sees your vault: not your holdings, your other dealers, your sales, your want list or your values.

A connected dealer learns only that the connection exists, when it was accepted, and if it is later ended. Before you accept, a dealer can learn that the email address on their record belongs to a confirmed Stack account, so that they can offer to connect.

You can disconnect a dealer at any time in My dealers. A dealer can also end a connection. Ending a connection removes that dealer’s invoices from your vault; it does not change the dealer’s own records.

8. When we share information

We do not sell your personal information, and we do not share it for cross-context behavioural advertising.

Service providers that process information for us under contract: cloud hosting and database providers, our web hosting provider, our email provider, which delivers account messages, and our image-reading provider, which reads the photos you ask Stack to identify. They may use the information only to provide their services to us.

Google: if you use the coin-shop search, the city, ZIP code or coordinates you search with are sent to Google Places to find shops. Opening Google Maps, a grading company’s verification page or a dealer’s website takes you to that service and its own privacy policy.

Legal and safety: we may disclose information when we believe in good faith it is required by law, subpoena or court order, or is necessary to protect the rights, property or safety of our users, the public or bullionOS, or to investigate fraud or abuse.

Business transfers: if bullionOS is involved in a merger, acquisition, financing or sale of assets, information may be transferred as part of that transaction, subject to this Policy.

Price data comes to you from bullionOS. Your vault is never sent to a price source to obtain it.

9. How long we keep information

We keep your account and vault for as long as your account exists. You can delete your account at any time in Settings; that removes your account, holdings, sales, want list, preferences and dealer connections from the live Service at once.

Copies in encrypted backups made before deletion expire on their normal schedule. Server logs are kept for a limited period. We may retain information where the law requires it or to resolve a dispute.

Invoices belong to the dealer that issued them and remain in that dealer’s records whether or not you use Stack.

10. Security

We use reasonable administrative, technical and physical safeguards, including encryption in transit, hashed passwords, hashed session tokens, and access controls that keep each collector’s vault separate from every other account and from every dealer.

Your vault is protected by your account; it is not end-to-end encrypted, so authorized bullionOS personnel who operate the Service can access stored data when needed to run or support it. No method of transmission or storage is completely secure, and we cannot guarantee absolute security. If we learn of a breach affecting your information, we will notify you as the law requires.

You are responsible for choosing a strong password you do not use elsewhere and for keeping it confidential.

11. Your choices and rights

Access and portability: export your holdings and sales as spreadsheets, or download a complete archive, at any time from Sales & exports.

Correction: edit your account details and records in the Service.

Deletion: delete your account in Settings, or ask us at the address below.

Depending on where you live, you may have additional rights under laws such as the California Consumer Privacy Act and similar state laws, including the right to know what personal information we hold, to correct or delete it, to obtain a copy, and not to be discriminated against for exercising these rights. To exercise a right, or to appeal a decision about a request, write to us at the address below. We will verify the request using the email address on your account and respond within the time the law allows. You may use an authorized agent where the law permits.

We do not knowingly collect sensitive personal information beyond the account credentials needed to sign you in, and we do not use or disclose it for any purpose other than providing the Service.

12. Children

Stack is for adults. It is not directed to anyone under 18, and we do not knowingly collect personal information from children. If you believe a child has given us information, contact us and we will delete it.

13. Where information is processed

Stack is operated from the United States and intended for users in the United States. Information is processed and stored in the United States. If you use the Service from elsewhere, you understand that your information will be transferred to and processed in the United States, where privacy laws may differ from those where you live.

14. Changes to this Policy

We may update this Policy. When we do, we will change the effective date above, and if the change is material we will give notice in the Service or by email before it takes effect. Your continued use of the Service after the effective date means the updated Policy applies.