FAQ
Proof of Sats sells collectible cards containing a real satoshi, identified and verifiable on the Bitcoin blockchain. This page answers the most common questions before purchase.
The Product
What is a Proof of Sats card?
A limited-edition, individually numbered physical collectible card containing a specific satoshi identified on the Bitcoin blockchain.
Each card brings together three elements: a printed collectible with a unique generative design, the public data needed to identify the satoshi it contains, and the private key that gives control over the associated satoshi, protected under a security seal.
Series 1 consists of 100 cards numbered from 1 to 100.
What is a satoshi?
A satoshi, or “sat,” is the smallest unit of a bitcoin. One bitcoin is made up of 100,000,000 satoshis.
Proof of Sats cards focus on certain satoshis that can be distinguished by their provenance, their place in Bitcoin’s history, or other characteristics valued by collectors.
What is a Rare Sat?
All satoshis have exactly the same monetary value within the Bitcoin protocol.
However, thanks to the indexing method known as Ordinal Theory, individual satoshis can be tracked and those with particular characteristics can be identified: position within a block, age, historical provenance, and so on.
The term Rare Sat is commonly used to describe satoshis sought after for these distinctive characteristics.
What exactly do I own when I buy a card?
You are purchasing the physical collectible. It gives you exclusive access to the satoshi associated with it.
The object itself, its collection number, its provenance data, and the satoshi it documents form an inseparable whole. Together, they make up the collectible card.
Will there be other series?
Yes. Series 2 is currently in preparation and is scheduled for release at the end of 2026.
Proof of Sats will also offer custom cards. For example, it will be possible to order a card containing a satoshi from a block mined on the day a child was born, an anniversary, or another meaningful date.
Each custom order will follow the same principle as the series: a genuine identified satoshi, independently verifiable on-chain provenance, and a unique physical collectible designed to be preserved.
The Bitcoin Contained in the Card
What is a UTXO?
Bitcoin does not use accounts with balances in the traditional sense. Instead, it uses distinct units of value called UTXOs, which move from one address to another.
A UTXO works somewhat like a banknote: it has a fixed value, belongs to a specific address, and cannot be partially spent. To spend part of it, the entire UTXO must be spent and the remaining amount returned as change.
Each Proof of Sats card is associated with its own UTXO containing 546 satoshis. The satoshi documented by the card occupies a specific position within that UTXO.
This structure is what makes the card possible. It also explains why moving the satoshi requires particular care.
Does each card actually contain Bitcoin?
Yes. Each card corresponds to a real UTXO recorded on the Bitcoin blockchain, containing 546 satoshis, including the satoshi documented by the card.
It is not a symbolic representation. The UTXO can be publicly verified before purchase.
The other 545 satoshis do not have any particular collectible characteristics. The amount of 546 sats corresponds to the technical format chosen for the UTXO associated with each card and has no particular financial significance.
Are the Series 1 satoshis rare under the Bitcoin protocol?
No, and the distinction is worth making clearly.
Bitcoin does not natively distinguish one satoshi from another. Ordinal indexing defines a formal rarity hierarchy — Uncommon, Rare, Epic, Legendary, Mythic — linked to the structure of blocks and periodic events on the Bitcoin network. The satoshis in Series 1 do not belong to any of these levels.
They fall into another category, commonly referred to by collectors as exotic sats: satoshis distinguished by their history rather than by a protocol-based rarity rule.
The Series 1 satoshis come from the first bitcoin of Block 9, whose block reward was the first mining reward ever spent in Bitcoin history. They therefore originate from the oldest bitcoin still in circulation.
The expression “rare sat” has become commonly used to refer more broadly to these sought-after satoshis. We use the term while clearly explaining what it means in each case.
Verification and Authenticity
Can I verify a card before buying it?
Yes, that is the whole point.
Every card number offered for sale is associated with public Bitcoin data that can be checked before purchase: the address, UTXO, satoshi number, and provenance. The corresponding card design is also visible in advance.
The existence of the UTXO and its history can be verified using any Bitcoin block explorer or your own node. Identifying a specific satoshi within the UTXO additionally requires an indexer compatible with ordinal indexing.
→ Verify a card at verify.raresatscards.com
Why does each card have a different pattern?
The design includes a generative guilloché pattern derived from characteristics specific to the satoshi.
The satoshi number is notably processed through SHA-256 to deterministically generate certain graphic elements.
The variation in the design is therefore not chosen randomly afterwards: it is directly linked to the card’s own data.
The pattern serves an aesthetic and identifying purpose while also making reproduction more difficult. However, it does not constitute cryptographic proof of authenticity on its own.
What security features are present on the card?
The cards combine several layers of verification: an individual number, microtext, generative guilloché pattern, authentication QR code, on-chain verification QR code, sealing mechanisms, and physical authentication features.
What is the difference between the two QR codes?
The authentication QR code identifies the card itself and provides access to its reference data.
The UTXO QR code allows the associated Bitcoin data to be verified.
This separation distinguishes the authenticity of the physical object from the verification of its on-chain contents.
Can a counterfeit Proof of Sats card be created?
As with any physical object, someone could attempt to reproduce its appearance.
However, a counterfeit cannot simply invent the Bitcoin provenance of an authentic satoshi and replace the corresponding card without creating inconsistencies between its serial number, public data, and the card’s different authentication features.
This is precisely why Proof of Sats combines physical verification with digital verification.
Private Key and Security Seal
Where is the private key?
Under a tamper-evident VOID security seal applied to the back of the card.
The key cannot be read without opening the seal. The material is designed to leave a visible and irreversible trace if it is opened or an attempt is made to remove it.
A damaged or altered seal should therefore be considered an indication that the confidentiality of the private key can no longer be guaranteed.
Does Proof of Sats keep a copy of my private key?
No.
The keys are generated and printed offline, then deleted from our systems. No copy is retained once the card has been finalized.
This has three direct consequences, which we fully accept: we cannot move the satoshi from your card; we cannot recover your key if it is lost or destroyed; and there is no master seed capable of reconstructing the keys of the collection, as each key is generated independently.
Can I open the seal?
Yes. The card belongs to you.
However, opening the seal reveals the private key and permanently changes the condition of the collectible. As with many sealed collectibles, the integrity of the packaging and security features may contribute to its appeal to a future collector.
If you intend to preserve the card as a collectible, we recommend leaving the seal intact. No action is required when you receive the card.
Proof of Sats does not guarantee any future resale value.
Can I move the satoshi to my own wallet?
Technically, yes, but please read the following carefully.
Each card’s UTXO contains 546 satoshis. The documented satoshi occupies either the first or the last position within that UTXO. This information can be verified for each card before purchase.
Because a UTXO cannot be partially spent, moving the satoshi necessarily spends the card’s UTXO and creates a new one. A standard Bitcoin wallet that does not track individual satoshis may take transaction fees from the end of the UTXO.
For a card whose collectible satoshi is in the last position, such a transaction can place that satoshi into the mining fees. It may then be permanently lost, with no possibility of recovery.
Proof of Sats advises against moving the satoshi and recommends keeping the card sealed.
If you nevertheless wish to move it, we provide a documented recovery tool designed to construct a transaction that preserves the satoshi’s position. Its use remains entirely your responsibility.
Purchase, Shipping and Resale
How are cards shipped?
Orders are shipped from France with tracking. Available destinations and estimated delivery times are shown during checkout.
Each card is delivered in its protective holder, designed for physical preservation, together with a signed Certificate of Authenticity.
What payment methods do you accept?
Credit/debit card, PayPal and Bitcoin.
Prices are not indexed to the price of Bitcoin. Changes in the BTC exchange rate do not change the price of the cards.
Can I return my card?
Yes, under the conditions set out in our withdrawal and return policy.
One point deserves particular attention: opening the seal exposes the private key and irreversibly alters the object.
A card returned after its security seal has been opened will therefore be subject to a reduction in the refund corresponding to this loss in value.
Can I sell my card to someone else?
A physical card may naturally be transferred or resold by its owner, subject to the rules applicable in their jurisdiction.
Proof of Sats does not participate in such transactions, does not organize them, and does not guarantee the buyer, the seller, or the price at which the card is sold.
How can a future buyer verify that a card is still intact?
They can inspect the physical security features, verify the card at verify.raresatscards.com, and check the corresponding public Bitcoin data.
An intact seal is particularly important, because once the seal has been opened, the private key may have been viewed.
The Project
What happens if Proof of Sats disappears one day?
Nothing changes as far as the satoshi in your card is concerned.
The UTXO, its history, and the provenance of the satoshi exist on the Bitcoin blockchain independently of Proof of Sats. This data does not belong to us and will remain independently verifiable by anyone using any Bitcoin node and a compatible indexer.
Our card-specific authentication services do, however, depend on our infrastructure. This is why the reference data for each card is also printed directly on the physical object.
Who is behind Proof of Sats?
Proof of Sats is led by Simtoshi, who can be found on X at @Simtoshi.
The project has also been publicly presented on Bitcointalk, where its technical design has been openly discussed, including its limitations.
→ Bitcointalk discussion thread
What exactly is the nature of your business?
Proof of Sats sells its own physical collectible products at fixed prices.
We do not provide trading or brokerage services. We do not provide investment advice. We do not hold crypto-assets on behalf of customers or retain their private keys. We do not provide wallet services or transfer crypto-assets on behalf of customers. We do not operate a secondary market or offer a buyback program. We do not promise any yield, return, or future appreciation in value.
Proof of Sats therefore does not present its cards as a way to obtain a financial return, but as physical collectibles whose Bitcoin provenance can be independently verified.