What it actually does
Arkham takes public blockchain data and attaches labels to addresses — not "this is a contract" but "this address belongs to a named fund, exchange or individual". It then lets you follow flows between those entities across chains.
The technique is not novel. Address clustering has been standard in blockchain analysis for a decade: if several addresses sign inputs to the same transaction they are probably controlled by one party; if an address consistently receives from a known exchange withdrawal pattern, its role can be inferred. Layer public information — disclosed holdings, published wallet addresses, on-chain interactions with known entities — and you build an attribution graph.
What Arkham did was package this as a consumer product with a good interface. Capability that was previously the preserve of compliance firms and law enforcement became something anyone could open in a browser.
How accurate is it?
Often very. For large, well-documented entities — major exchanges, protocol treasuries, publicly disclosed institutional holdings — the attribution is reliable because the underlying information is largely public.
For smaller and individual addresses it is considerably weaker, and the failure mode is the dangerous one: the interface presents an inference with the same visual confidence as a fact. A wallet labelled with a person's name looks identical to a wallet labelled with an exchange's name, but the evidence behind the two is not remotely comparable.
Clustering heuristics have known failure cases. CoinJoin transactions deliberately break them. Shared custody arrangements produce false positives. An address that received one payment from a known entity is not that entity. None of this reasoning is visible to you, because the methodology is not published.
So: treat labels as leads. Confirmed for large entities, plausible for medium ones, and for anything concerning an individual, unverified. Acting on an attribution you cannot check is how people end up publicly wrong about who owns what.
The uncomfortable lesson
The most valuable thing about Arkham, for most readers, is not using it. It is understanding that it exists.
Public blockchains are permanent, complete and open. Every transaction you have ever made is available to anyone, forever, and it will be analysable with better tools in ten years than exist today. The pseudonymity people imagine they have is not a property of the chain — it is a temporary consequence of nobody having bothered to look.
Once an address is linked to you — through a KYC exchange withdrawal, a public donation address, a reused address, a purchase with a delivery address — the entire history connected to it is linked too. Retroactively. There is no way to unlink it.
That is the real finding, and Arkham demonstrates it more persuasively than any amount of writing. Our guide on what an explorer learns about you covers the practical consequences, and the honest conclusion is that on a transparent chain privacy is a discipline rather than a default.
The ethical argument
Arkham has attracted sustained criticism, particularly over its early bounty mechanism for deanonymising addresses. The counter-argument is that the data is public and the analysis is legal, which is true. Both positions can be held at once: the capability exists regardless of who packages it, and packaging it as a consumer product changes who can use it. We list it because it is significant, not because we endorse the model.
Practical uses
Setting aside the ethics, there are legitimate uses and they are worth naming.
Following institutional flows is the main one — seeing that a treasury moved funds to an exchange is a real signal, and it is public information presented usefully. Security researchers tracing stolen funds after an exploit find the cross-chain flow view genuinely helpful, because attackers bridge and the trail otherwise fragments across explorers.
Journalists and analysts use it for the same reason anyone uses a research tool. And, more mundanely, it is a good way to check whether an address you have been given belongs to the entity you were told it belongs to — though the caveats about attribution confidence apply exactly as much in that direction.
What it is not is a block explorer. It will not help you check whether a transaction confirmed, read a contract, or work out why a fee was high. For those, use an actual explorer — our directory covers fifty of them.