The long-standing criticism of proof of reserves is that it proves too little. The more urgent problem in 2026 is that a growing share of it has stopped being maintained while continuing to look maintained.
Nothing announced its own failure. Pages kept rendering, footers kept updating, and the underlying data stopped moving.
The most rigorous implementation in the industry. Proof of reserves and liabilities run twice weekly on a Merkle sum tree, letting any user verify their own balance was included, with open-source verification tooling still receiving commits in April 2026. The exchange announced permanent closure on 23 July after a strategic review, ending an eleven-year run.
The page is live, styled as current, and carries a 2018 to 2026 footer. The only attestation on it is a Mazars verification snapshotted 7 December 2022. Mazars suspended all crypto client work nine days later. The page has been frozen for roughly three years and eight months while presenting as a live transparency artifact.
The independent scorekeeper of attestation quality. The tracker now returns a 404 and is still linked from his own topics page. His proof-of-reserves reading list has not been added to since 2023, while his adjacent research carries material from 2025 and 2026. Nobody replaced him.
Armanino exited crypto after being named in FTX-related litigation. Its team spun out as The Network Firm and the product now trades as LedgerLens, which is a vendor marketing site rather than a public attestation dashboard.
Published monthly without interruption since November 2022, with zk-STARK verification and open-source self-verification tooling. The strongest continuously maintained programme in the category.
Genuinely rigorous: CPA-attested Merkle tree with unusually broad scope covering spot, margin, staking and futures collateral. The published snapshot is four months stale against a quarterly commitment.
Publishes monthly with zk-SNARK enhancement and open-source verification code, but has had no third-party auditor since Mazars withdrew in December 2022.
A genuine new entrant, covering roughly 28,000 BTC across customer and corporate treasury holdings. Evidence against the assumption that everyone has abandoned the practice.
A reader visiting Crypto.com's proof-of-reserves page today, or following the link on Nic Carter's topics page, gets no indication that either has been abandoned unless they check the dates themselves. The page returns a success status. It renders. It looks like transparency.
This is the same shape as the failures in our custody timeline: a mechanism that appears to be working, right up until someone checks. A stale attestation is arguably worse than no attestation, because it displaces the diligence that its absence would have prompted.
And the largest custodian in the market publishes no exchange-wide attestation at all. Coinbase, named sole or primary custodian for roughly 84% of US spot bitcoin ETF holdings, provides proof of reserves only for its wrapped assets, on the stated position that audited public-company financials serve the purpose. That is defensible. It also means the single largest concentration of custodied bitcoin in the world is attested through quarterly filings rather than through anything a holder can check against the chain. We measure that concentration in Bitcoin is decentralized, its custody is not.
The conclusion tightens rather than changes. Reserve attestation never prevented a failure. It is now also decaying as a practice, in public, without announcement. The question worth asking of any platform is unchanged: not whether it publishes an attestation, but how many independent parties would have to fail before your bitcoin moved without your consent.
Proof of Custody, The Proof of Reserves Estate Is Quietly Decaying, proofofcustody.io/research/proof-of-reserves-decayIt remains a reasonable minimum expectation, but check the date on the snapshot before treating it as meaningful. Several prominent proof-of-reserves pages render normally while displaying attestations that are years old, and at least one has been frozen since December 2022 while carrying a current-year footer.
OKX has published monthly without interruption since November 2022 with zk-STARK verification. Kraken remains rigorous and broad in scope but its published snapshot is currently four months stale. Binance publishes monthly but has had no third-party auditor since December 2022. Block published its first report in April 2026.
Not for the exchange as a whole. Coinbase publishes proof of reserves for its wrapped assets, and its stated position is that audited financial statements as a public company serve the purpose. It is the named sole or primary custodian for roughly 84% of US spot bitcoin ETF holdings.
Because it displaces diligence. A reader who sees an attestation page assumes the question has been answered, and a page that renders normally gives no signal that its data stopped moving years ago. The absence of an attestation prompts a question; a stale one prevents it.