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Wallet of Satoshi

Google Play

Our wallet review process

We examine wallets starting at the code level and continue all the way up to the finished app that lives on your device. Provided below is an outline of each of these steps along with security tips for you and general test results.

Developer

Wallet of Satoshi

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Released

19th May 2019

Custody

Custodial!

As part of our Methodology, we ask: Does the product allow self-custody?

The answer is "no". Therefore we marked it as "Custodial: The provider holds the keys".
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Source code

Application build

Build cannot be done because the source code is not publicly available.

Distribution

Google Play
4/5 stars via 758 ratings

Platform notes

On the Google Play Store, there are many apps that have Bitcoin in their name or description but don’t allow the user to use Bitcoin or they don’t look like Bitcoin wallets but turn out to be. We run our tests and document our findings.

Passed 6 of 9 tests

We answered the following questions in this order:
We stopped asking questions after we encountered a failed answer.

Do many people use this product?

The answer is "yes".
If the answer were "no", we would mark it as "Few users" and the following would apply:

The answer is "no". We marked it as "Few users".

We did not ask this question because we failed at a previous question.
If the answer were "no", we would mark it as "Few users" and the following would apply:

We focus on products that have the biggest impact if things go wrong and this one probably doesn’t have many users according to data publicly available.

Is this product the original?

The answer is "yes".
If the answer were "no", we would mark it as "Fake" and the following would apply:

The answer is "no". We marked it as "Fake".

We did not ask this question because we failed at a previous question.
If the answer were "no", we would mark it as "Fake" and the following would apply:

The bigger wallets often get imitated by scammers that abuse the reputation of the product by imitating its name, logo or both.

Imitating a competitor is a huge red flag and we urge you to not put any money into this product!

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Is it a wallet?

The answer is "yes".
If the answer were "no", we would mark it as "Not a wallet" and the following would apply:

The answer is "no". We marked it as "Not a wallet".

We did not ask this question because we failed at a previous question.
If the answer were "no", we would mark it as "Not a wallet" and the following would apply:

If it’s called “wallet” but is actually only a portfolio tracker, we don’t look any deeper, assuming it is not meant to control funds. What has no funds, can’t lose your coins. It might still leak your financial history!

If you can buy Bitcoins with this app but only into another wallet, it’s not a wallet itself.

Is it for bitcoins?

The answer is "yes".
If the answer were "no", we would mark it as "A wallet but not for Bitcoin" and the following would apply:

The answer is "no". We marked it as "A wallet but not for Bitcoin".

We did not ask this question because we failed at a previous question.
If the answer were "no", we would mark it as "A wallet but not for Bitcoin" and the following would apply:

At this point we only look into wallets that at least also support BTC.

Can it send and receive bitcoins?

The answer is "yes".
If the answer were "no", we would mark it as "Can't send or receive bitcoins" and the following would apply:

The answer is "no". We marked it as "Can't send or receive bitcoins".

We did not ask this question because we failed at a previous question.
If the answer were "no", we would mark it as "Can't send or receive bitcoins" and the following would apply:

If it is for holding BTC but you can’t actually send or receive them with this product then it doesn’t function like a wallet for BTC but you might still be using it to hold your bitcoins with the intention to convert back to fiat when you “cash out”.

All products in this category are custodial and thus funds are at the mercy of the provider.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Does the product use Chaumian eCash?

The answer is "no".
If the answer were "yes", we would mark it as "Uses Chaumian eCash" and the following would apply:

The answer is "yes". We marked it as "Uses Chaumian eCash".

We did not ask this question because we failed at a previous question.
If the answer were "yes", we would mark it as "Uses Chaumian eCash" and the following would apply:

Chaumian eCash is a form of electronic token system that provides some privacy benefits over custodial services, but requires trust in mint operators. While the technology itself is promising, wallets implementing it effectively connect to custodial services. There are currently two main incompatible protocols for Chaumian eCash:

  • Cashu
  • Fedimint While these systems aim to enable what could be called “fist-reach custody” (where users have physical access to their custodians, like a trusted family member), wallets cannot enforce this model. We are seeing users gravitate towards popular mints rather than local ones, which defeats the intended trust model. Even in an ideal “Uncle Jim” scenario where users know their mint operator personally:
  • The mint operator can still lose or steal the funds
  • The mint could be compromised by hackers
  • The mint operator could face regulatory pressure
  • Technical issues could result in loss of funds

While Chaumian eCash may serve valid use cases, users should understand that:

  • They are trusting the mint operator with custody of their funds
  • They should ideally use local mints operated by people they know and can reach
  • The privacy benefits come at the cost of giving up self-custody
  • The tokens are only as good as the mint operator’s promise to redeem them
The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Does the product allow self-custody?

The answer is "yes".
If the answer were "no", we would mark it as "Custodial: The provider holds the keys" and the following would apply:

The answer is "no". We marked it as "Custodial: The provider holds the keys".

We did not ask this question because we failed at a previous question.
If the answer were "no", we would mark it as "Custodial: The provider holds the keys" and the following would apply:

A custodial service is a service where the funds are held by a third party like the provider. The custodial service can at any point steal all the funds of all the users at their discretion. Our investigations stop there.

Some services might claim their setup is super secure, that they don’t actually have access to the funds, or that the access is shared between multiple parties. For our evaluation of it being a wallet, these details are irrelevant. They might be a trustworthy Bitcoin bank and they might be a better fit for certain users than being your own bank but our investigation still stops there as we are only interested in wallets.

Products that claim to be non-custodial but feature custodial accounts without very clearly marking those as custodial are also considered “custodial” as a whole to avoid misguiding users that follow our assessment.

We have to acknowledge that a huge majority of Bitcoiners are currently using custodial Bitcoin banks. If you do, please:

  • Do your own research if the provider is trust-worthy!
  • Check if you know at least enough about them so you can sue them when you have to!
  • Check if the provider is under a jurisdiction that will allow them to release your funds when you need them?
  • Check if the provider is taking security measures proportional to the amount of funds secured? If they have a million users and don’t use cold storage, that hot wallet is a million times more valuable for hackers to attack. A million times more effort will be taken by hackers to infiltrate their security systems.
The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Is the source code publicly available?

The answer is "yes".
If the answer were "no", we would mark it as "No source for current release found" and the following would apply:

The answer is "no". We marked it as "No source for current release found".

We did not ask this question because we failed at a previous question.
If the answer were "no", we would mark it as "No source for current release found" and the following would apply:

A wallet that claims to not give the provider the means to steal the users’ funds might actually be lying. In the spirit of “Don’t trust - verify!” you don’t want to take the provider at his word, but trust that people hunting for fame and bug bounties could actually find flaws and back-doors in the wallet so the provider doesn’t dare to put these in.

Back-doors and flaws are frequently found in closed source products but some remain hidden for years. And even in open source security software there might be catastrophic flaws undiscovered for years.

An evil wallet provider would certainly prefer not to publish the code, as hiding it makes audits orders of magnitude harder.

For your security, you thus want the code to be available for review.

If the wallet provider doesn’t share up to date code, our analysis stops there as the wallet could steal your funds at any time, and there is no protection except the provider’s word.

“Up to date” strictly means that any instance of the product being updated without the source code being updated counts as closed source. This puts the burden on the provider to always first release the source code before releasing the product’s update. This paragraph is a clarification to our rules following a little poll.

We are not concerned about the license as long as it allows us to perform our analysis. For a security audit, it is not necessary that the provider allows others to use their code for a competing wallet. You should still prefer actual open source licenses as a competing wallet won’t use the code without giving it careful scrutiny.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Is the decompiled binary legible?

The answer is "yes".
If the answer were "no", we would mark it as "Obfuscated" and the following would apply:

The answer is "no". We marked it as "Obfuscated".

We did not ask this question because we failed at a previous question.
If the answer were "no", we would mark it as "Obfuscated" and the following would apply:

When compiling source code to binary, usually a lot of meta information is retained. A variable storing a masterseed would usually still be called masterseed, so an auditor could inspect what happens to the masterseed. Does it get sent to some server? But obfuscation would rename it for example to _t12, making it harder to find what the product is doing with the masterseed.

In benign cases, code symbols are replaced by short strings to make the binary smaller but for the sake of transparency this should not be done for non-reproducible Bitcoin wallets. (Reproducible wallets could obfuscate the binary for size improvements as the reproducibility would assure the link between code and binary.)

Especially in the public source cases, obfuscation is a red flag. If the code is public, why obfuscate it?

As obfuscation is such a red flag when looking for transparency, we do also sometimes inspect the binaries of closed source apps.

As looking for code obfuscation is a more involved task, we do not inspect many apps but if we see other red flags, we might test this to then put the product into this red-flag category.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.
Wallet of Satoshi  App Store

Application information

Update — v3.1.7 Self-Custody Claims Review (2025-10-09)

Summary of Change

Wallet of Satoshi announced a “Self-Custody Mode” in version v3.1.7, marketed as a major shift toward user-controlled Lightning funds.

The update claims users can hold keys locally while maintaining usability through the Spark protocol.

1. Public Announcement

2. Expert and Community Discourse

Participant Position Reference
@boyacaxa / @conduition_io Argue that calling Spark-based mode “self-custody” is misleading because operators can rug users during transfers. boyacaxa, conduition_io
@kphur (Spark creator) States that operator honesty is only required at the time of transfer, and users can unilaterally exit later. Spark trust model
@TheBlueMatt / @NicolasDorier Contend that operators can modify software to redirect future funds, implying that full self-custody is not guaranteed. BlueMatt, Dorier
others Suggest renaming it “trustodial” to reflect the trust assumptions involved. Tweet

3. App Behavior (Observed)

  • Settings → Self Custody Mode prompts the user to log in to Backup first.
  • Activating the mode creates a new wallet (0 sats) with an independent 12-word seed phrase.
  • Backup options include Google Drive and Manual (Advanced).
  • Advanced mode requires biometric/PIN unlock, then shows the seed phrase, confirming through word re-entry.
  • Original custodial balance becomes hidden; switching back to “WoS Custody” restores access to the legacy balance.
  • The UI implies the two modes operate on separate wallet instances.

4. Verification Gaps

  • Backend communication and Spark node behavior remain unverified.
  • Cannot yet confirm whether unilateral exit paths work without operator cooperation.
  • Current assessment relies solely on public statements and local UI observation.
  • Spark documentation indicates that the 12 word seed phrases are BIP39 compliant

Verdict

The trust and custodial model for the wallet is more nuanced.

The user can unilaterally withdraw funds to Bitcoin L1 using the community-made spark-recovery tool. Use at your own risk: https://github.com/BlitzWallet/spark-recover

Spark is a “shared signing protocol”: https://docs.spark.money/spark/spark-tldr
Spark operators are co-signers. For a transaction to happen, both the user’s signature and the operator’s signature are needed. The operator does not have the user’s private key.

However, self-custodial at WalletScrutiny means exclusive user control—the user alone can authorize spends without any third-party co-signature or trust. WoS, even with Spark, doesn’t offer this because operators must co-sign off-chain transfers. Risk exists at hand-off if operators fail to delete old keys; see Spark’s trust model: https://docs.spark.money/spark/trust-model

Thus we are retaining the custodial verdict.

2021-05-25

This is a custodial wallet according to their website’s FAQ:

It is a zero-configuration custodial wallet with a focus on simplicity and the best possible user experience.

and therefore not verifiable.

Tests performed by Leo Wandersleb, Daniel Andrei R. Garcia

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Do your own research

In addition to reading our analysis, it is important to do your own checks. Before transferring any bitcoin to your wallet, look up reviews for the wallet you want to use. They should be easy to find. If they aren't, that itself is a reason to be extra careful.